Tidal Pools And Water Changes

[Lynden]

One only needs to ask Lynden to find out just how ready I am to criticise him where justified, eh Lynden?

I figure I've been doing pretty good lately.

I believe I once said that bacteria can multiply to handle a great degree of overstocking, but this can still be a major problem in a marine system because of the nitrates and phosphates that are produced from wastes and feeding. In addition, the territorial pressure created from overstocking can result in dominant fishes reducing the stocking to the correct level, so either way if one truly overstocks then one will have tank issues some time or another.

 

[Tommy Gun]

Ok, now it seems like we are on to some constructive debate! I like this much better.

The concepts of fish growing are fairly well understood in science due to the studies done on farmed fish. It shows that the fish growth can be cyclical, many fish have periods of fast growth in summer with an abundance of food and then slow down in winter due to less food.

Very true, and I do understand that growth in many animals is Dependant on many factors resulting in it growing faster at one time versus another. However, what I am trying to focus on is the factors in an aquarium - which, for most situations, removes the summer/winter factor, the abundance of food available (meaning a fishes' food source wont fluctuate so long as we keep providing it), and the body of water they live in is not subjected to any rainy season or drought. With me so far? Ok...what I am trying to say is that even if we provide all optimum conditions at 100% of the time, short of an adequate amount of space, what happens? A fish's growth stops or slows?

The rest of the fish was in perfect proportion and showed no signs of bulging organs.

Ok, well let me put it this way....what I understand is that it is not a matter of the fishes' organs growing any larger than they normally would, but that the fish's organs grow to normal size when its body does not....which doesn't exactly result in bulging organs, but perhaps one interfering with another. For example...and please understand that I am not a biologist or internal expert....a fish's skeleton grows slower than its heart and liver and so much so that the heart begins to stop the liver from functioning.

You need to look at two fish which are the same (so both balas) but one can keep its organs smaller with the skeleton, and the other cannot keep smaller organs. The former is more likely to survive a medium term entrapment in a smaller or less ideal body of water than the latter, and thus is more likely to breed, giving rise to fry which will not carry the trait.

Otherwise, maybe I can make myself a bit more understood if I explain that I am not speaking of any biological factors (e.g. genes, DNA, birth defects) but rather other outside influences such as cramped conditions. Obviously anyone could place two of the most perfect examples of a bala shark in a 10 gallon tank and they are not going to thrive as they otherwise should, right?

Both show that a fish can start growing again once better conditions prevail. The fish will always be behind its peers that did not suffer the "stunting". The fish will start to grow faster. Remembering that a fish tends to grow forever until it dies (albeit at a very slow rate once larger) then the fish probably won't quite reach the same sizes, but it does catch up.

My point there was that yes, I realize that in nature conditions can improve (e.g. a drought ends and hence, a fish can now freely swim to a larger lake or whatever the case may be), however, in an aquarium, this may never happen unless the person keeping the fish moves it to a larger tank. Then what happens? Will a bala shark only grow to a length of 4 inches in a 10 gallon tank (hypothetical, of course) but still live as long as its 'brother' who is kept in a 200 gallon tank? I say no. And in either case, if this was possible, then the 'beginner's myth' of stunting is true.

It depends on how you define "stunting". As I mentioned above, many fish don't grow as large in an aquarium

Good point. Obviously I am speaking of some more extreme cases. I completely understand what you are saying since one of my more favorite LFS's (for 'window shopping' anyways since they are over priced IMHO) has a 1200 gallon tank with a ID shark in it which is no longer than 2 and a half feet in length, but have seen mounted specimens on a Cabelas (go figure, huh?) that were easily over 4 feet. But again, that is not what I am really focusing on.

It could be, though is there any evidence that any deaths are caused by stress due to stunting? Let's be honest, most people who will stunt a fish for some time tend not to be those with the best interests of the animal in mind, or at least may be unaware of the optimum way to maintain good water conditions (I am not implying that all are actively doing this, but they may know no different). How do we know that the death is in any way related to stunting?

Another good point....how then, when you come across a person (on a forum or otherwise), do you explain that keeping a bala shark in a 10, 20, or even 55 gallon tank (a very common situation based upon my observations) is not a good idea? Or do you say nothing? I guess what has been a large motivator for me to help out with this issue when I come across it was my trip down to the Shedd Aquarium earlier this year because, even though I have read quite a bit about some fish growing to huge sizes that may seem improbable when looking at one in an LFS, it wasn't until I saw the fish in actual 'life size' first hand that I completely realized the gravity of the situation. For example (and these are my own photos):

^A bala shark (my wife's hand under it) and if you look closely, that is a giant gourami behind it

^Knife fish (wife's hand under it)

^Fire Eel (my hand under it)...very common in my neck of the woods for some reason

^Tinfoil Barb

Granted, these are freshwater fish and I realize that in Lynden's case, he is dealing with marine fish, however, I still hold on to my original point which was IF he DIDN'T move some of the fish into a larger tank, problems will ensue.

Do I make a little bit more sense now?

No, it is because I do not want to criticize you for stating something when you didn't. Rather than protecting Lynden, it was to prevent unfair criticism of you. One only needs to ask Lynden to find out just how ready I am to criticize him where justified, eh Lynden?

Fair enough and apologize if you took any offense to that comment of mine. However, based upon some things you have said to me, I do have some reason to believe that you might have singled me out in the past - probably the best example of that was the discussion on what marine fish fit well in a 10 gallon tank where I was trying to make the point that a 'dwarf' lionfish isn't a good 10 gallon candidate IMO, but you set me on fire for saying that the large variety can reach one or two feet. Obviously my main point there wasn't the size of a P. Volitans, but the size of a dwarf lion but you wouldn't let that one item go. And for the record, I still don't see how you could dismiss information on a governmental website (that one was actually a sub-department of the USDA) but hold so strongly onto the fishbase website information. In fact, after digging a little bit deeper into how fishbase gets its information, it is very possible that you could very well provide them information on what you saw during a dive and they would try to verify that, but I don't see how they could with 100% accuracy. Don't get me wrong though, I am not trying to say fishbase isn't reliable, but it doesn't look like it isn't completely infallible either. Perhaps the lionfish that was discussed on the website I provided simply grew larger than normal due to global warming or some of the points you have made in your last reply to this thread? Again, not trying to support or deny anyone or any thing, just throwing the idea out there. Logically, one can certainly argue the fact that unless someone has seen every single lionfish in the world today, he or she cannot say with absolute certainty the exact size of the largest one...only the largest ever recorded. Anyways, lots of arguments can be made and I doubt we can solve the world's problems here.

 

[Tommy Gun]

One only needs to ask Lynden to find out just how ready I am to criticise him where justified, eh Lynden?

I figure I've been doing pretty good lately.

I believe I once said that bacteria can multiply to handle a great degree of overstocking, but this can still be a major problem in a marine system because of the nitrates and phosphates that are produced from wastes and feeding. In addition, the territorial pressure created from overstocking can result in dominant fishes reducing the stocking to the correct level, so either way if one truly overstocks then one will have tank issues some time or another.

I do have to retract some of my statement because, upon further review, I realize that it was not you who said that, but actually someone who had said that when speaking about how many feeder fish should be kept in a FW tank - although they were trying to suggest that feeding them to a lionfish was 'all-good' in his estimation (and probably why I got confused about it being a marine or FW discussion). Anyways, I agree completely with your thoughts here lynden and again, apologize for my engaging my 'mouth' (fingers) before verifying my doubts.

That being said though, what, in your opinion, has led to your success with keeping some usually territorial and perhaps aggressive marine fish in a 33 gallon tank?

Granted, I realize that a lot of 'rules' can be broken when done so over a short period of time and/or if the fish are all juveniles (perhaps in some cases, if all are adults...although I can't think of one right now), but I would be in opposition to anyone who would say that breaking some rules for a long period of time is ok, or at least if implying that it can be done by anyone in every situation. (To sum that up, I am not trying to say that you are not doing what you say you are, just that it might not work as well for me or someone else)

 

[andywg]

Very true, and I do understand that growth in many animals is Dependant on many factors resulting in it growing faster at one time versus another. However, what I am trying to focus on is the factors in an aquarium - which, for most situations, removes the summer/winter factor, the abundance of food available (meaning a fishes' food source wont fluctuate so long as we keep providing it), and the body of water they live in is not subjected to any rainy season or drought. With me so far? Ok...what I am trying to say is that even if we provide all optimum conditions at 100% of the time, short of an adequate amount of space, what happens? A fish's growth stops or slows?

The growth seems to slow, but not stop entirely, hence you see some hideously deformed animals in too small tanks. however, the fish is unlikely to ever reach a full size and as such will sty smaller, but may well live a good life (see a point below).

Ok, well let me put it this way....what I understand is that it is not a matter of the fishes' organs growing any larger than they normally would, but that the fish's organs grow to normal size when its body does not....which doesn't exactly result in bulging organs, but perhaps one interfering with another. For example...and please understand that I am not a biologist or internal expert....a fish's skeleton grows slower than its heart and liver and so much so that the heart begins to stop the liver from functioning.

The science does not support this, the post I linked to has bignose looking at some scientific papers and giving his views:

The reason I ask is that bulging organs, to me, does not seem to be the way nature works. Stunted populations occur all the time in nature -- limitations on food or pollution in the native waters frequently result in populations that are smaller than norms. Predation can also be a common cause. Sport fishermen know this when the state wildlife and fishing commissions restrict fishing in a lake or stream in order to give the populations a chance to recover.

In fact, long-term stunting is the reason we have the dwarf varieties of some of our favorite fish: dwarf gouramies, dwarf cichlids, etc.

Finally, from "Development and aging of the liver and pancreas in the domestic carp, Cyprinus carpio: From embryogenesis to 15-year-old fish" by Fishelson L and Becker K in ENVIRONMENTAL BIOLOGY OF FISHES Vol 61 Issume (1) pages 85-97, 2001,

"In 15-year-old experimentally stunted fish (110-120 mm TL) the liver and pancreas resemble those of juvenile fish appearing much healthier than those of 8-10 year old large carp from commercial ponds. "

Sure, those are only a few organs and a general assumption about all the organs cannot be completely made completlely accurately, but the liver is a fairly sensiitve organ since it does a lot of the housekeeping of the fish's immune system.

Here is another from "Effect of stunting of juvenile bighead carp Aristichthys nobilis (Richardson) on compensatory growth and reproduction" by Santiago CB, Gonzal AC, Aralar EV, Arcilla RP in AQUACULTURE RESEARCH Vol 35 Issue (9) pages 836-841, JUL 23 2004:

"The carp stunted for 6, 12 and 18 months showed growth compensation, although their weights and lengths were slightly lower than those of the control fish. The body weight and length of fish stunted for 24 months were the lowest throughout the rearing period. Sexual maturation occurred only in the control fish and those stunted for 6 and 12 months. However, the onset of gonad maturity was delayed significantly (P<0.05) in males stunted for 12 months and in both groups of stunted female fish. "

Stunting delayed the development of the fish, but no mention of bulging organs or other deformities.
---------

I believe that some of this comes from the knowledge that teleosts (bony fishes) are considered to have indeterminate growth, that is, they continue to grow over their entire lifespan. However, as some point in their lives, they devote some, and usually most of their resource intake into reproduction -- generating eggs and maturing their sexual organs. In almost every case, this results in a sigmoidal growth curve: slow at first as fry can only take in a certain amount of food, then rapid in their first year(s) as growth is dominant, then almost all resources get devoted to reproduction related activities.

Ultimately, why would nature allow the growth rates of the skeleton and the organs to be different?!?

Otherwise, maybe I can make myself a bit more understood if I explain that I am not speaking of any biological factors (e.g. genes, DNA, birth defects) but rather other outside influences such as cramped conditions. Obviously anyone could place two of the most perfect examples of a bala shark in a 10 gallon tank and they are not going to thrive as they otherwise should, right?

Not thrive in that they will respond (due to their genetics and physiology) with slower growth rates. Just how bad their lives will be is unsure, as the science posted above may indicate.

My point there was that yes, I realize that in nature conditions can improve (e.g. a drought ends and hence, a fish can now freely swim to a larger lake or whatever the case may be), however, in an aquarium, this may never happen unless the person keeping the fish moves it to a larger tank. Then what happens? Will a bala shark only grow to a length of 4 inches in a 10 gallon tank (hypothetical, of course) but still live as long as its 'brother' who is kept in a 200 gallon tank? I say no. And in either case, if this was possible, then the 'beginner's myth' of stunting is true.

Grow as long, probably not provided they both live to the same age, as one will have a period of longer growth. It is posible that the previously stunted could end up as long, but just take far longer.

Good point. Obviously I am speaking of some more extreme cases. I completely understand what you are saying since one of my more favorite LFS's (for 'window shopping' anyways since they are over priced IMHO) has a 1200 gallon tank with a ID shark in it which is no longer than 2 and a half feet in length, but have seen mounted specimens on a Cabelas (go figure, huh?) that were easily over 4 feet. But again, that is not what I am really focusing on.

That is the largest captive ID shark I have heard of, with examples over 18" very rare in the home aquarium. the reasons for this are probably myriad, but one must also remember that not all pngassius are giants (some max out at 8" accprding to fishbase).

Another good point....how then, when you come across a person (on a forum or otherwise), do you explain that keeping a bala shark in a 10, 20, or even 55 gallon tank (a very common situation based upon my observations) is not a good idea? Or do you say nothing? I guess what has been a large motivator for me to help out with this issue when I come across it was my trip down to the Shedd Aquarium earlier this year because, even though I have read quite a bit about some fish growing to huge sizes that may seem improbable when looking at one in an LFS, it wasn't until I saw the fish in actual 'life size' first hand that I completely realized the gravity of the situation.

I like to consider CFC's equations that a tank should be at least 4x the fish size in length, and 2x in height and depth wherever possible. With balas they tend to need more as they are suxh a skittish fish.

Granted, these are freshwater fish and I realize that in Lynden's case, he is dealing with marine fish, however, I still hold on to my original point which was IF he DIDN'T move some of the fish into a larger tank, problems will ensue.

Do I make a little bit more sense now?

But would they? Can we be absolutely sure it would be purely from being "overstocked" or "stunted"?

And for the record, I still don't see how you could dismiss information on a governmental website (that one was actually a sub-department of the USDA) but hold so strongly onto the fishbase website information. In fact, after digging a little bit deeper into how fishbase gets its information, it is very possible that you could very well provide them information on what you saw during a dive and they would try to verify that, but I don't see how they could with 100% accuracy.

That page on fishbase gives the details of a scientific resource book from whence the details came. If you want to check you go to that book. As I stated before, your government website does not give it source or provide any details. And do you really trust everything your government tells you without question?

 

[Tommy Gun]

But would they? Can we be absolutely sure it would be purely from being "overstocked" or "stunted"?

I would say yes, and we can be somewhat sure. In many cases of fish death or even in disease, we feel comfortable saying to ourselves "Oh, poor little guy never had a chance because the Ich/bloat/HLLE/fungus/infection/etc/etc/etc was just too much", when some of us rarely consider that many times this these ailments can actually be a secondary issue. For example, by almost any account, fish have a relatively easy time with fighting off Cryptocaryon irritans on their own accord and in fact, by quite a few accounts, fish in the wild are rarely found with such vast infections as we see in our aquariums. Granted, marine fish have cleaners and such to help curb that issue, however, I think it is important to consider that maintaining a cleaner in an aquarium is not an absolute proflactic against the problem either which I feel provides an argument that there are other factors involved that may not be as emphasized in nature. In any case, I do feel that it is generally accepted that the prevention of ich can be easily acheived via husbandry which allows our fish to remain healthy, including the provision of ideal water quality which becomes more and more challenging as a tank holds a higher number of fish (leading to higher waste production that degrades water quality) and as a lower number of fish increase in size (and in waste production that degrades water quality).

However, parasites are only the tip of the iceberg and many ailments are more directly linked to water quality such as lateral line diseases (and/or hole in the head), swim bladder issues, tail/fin rot, issues which cause dropsy like symptoms, etc. Again, in many cases these water quality issues can stem directly from overstocking.

So, in short, I would say yes, overstocking and the resulting side effects, whether theoretical or scientifically proven, can be blamed on a wide array of problems in fish. This may be compounded in a marine tank due to the fact that the role of osmosis requires saltwater livestock to 'drink' more water than their freshwater counterparts, meaning that along with that water, the fish are also ingesting the unhealthy attributes included (perhaps the reason it is often suggested to stock much 'lighter' than in a FW tank?)

In a reef tank, overstocking even more of a problem because the resultant excess of nitrates and phosphates play a larger, more detrimental role on corals. Phosphates can reduce calcification and while it may be nearly impossible to kill a fish with nitrates directly, corals, anemones, and some inverts are an exception (perhaps the reason why we are often suggested to again stock lightly, and keep nitrate levels as low as possible).

 

[andywg]

But would they? Can we be absolutely sure it would be purely from being "overstocked" or "stunted"?

I would say yes, and we can be somewhat sure. In many cases of fish death or even in disease, we feel comfortable saying to ourselves "Oh, poor little guy never had a chance because the Ich/bloat/HLLE/fungus/infection/etc/etc/etc was just too much", when some of us rarely consider that many times this these ailments can actually be a secondary issue.

But how can we be sure it is not general bad husbandry or just not paying attention to the water conditions. Water stocking is likely to lead to water quality issues, but sufficient water changes and filtration could allow some pretty hefty stocking, especially if one employs a decent algae turf scrubber.

For example, by almost any account, fish have a relatively easy time with fighting off Cryptocaryon irritans on their own accord and in fact, by quite a few accounts, fish in the wild are rarely found with such vast infections as we see in our aquariums.

This is probably more due to the aquarium being a closed loop. The same fish are in the same water with the same reproducing parasite. There is no chance of a tide or wave washing the parasite into the open sea. The parasite does not want to massively infect the host as if the host dies, so does the pathogen.

Granted, marine fish have cleaners and such to help curb that issue, however, I think it is important to consider that maintaining a cleaner in an aquarium is not an absolute proflactic against the problem either which I feel provides an argument that there are other factors involved that may not be as emphasized in nature. In any case, I do feel that it is generally accepted that the prevention of ich can be easily acheived via husbandry which allows our fish to remain healthy, including the provision of ideal water quality which becomes more and more challenging as a tank holds a higher number of fish (leading to higher waste production that degrades water quality) and as a lower number of fish increase in size (and in waste production that degrades water quality).

Be careful here. While there can be little doubt that an understocked tank will make it easier to keep parameters in check, simply overstocking does not, in and of itself, create the problems. It is more the matter of overstocking without being able to deal with it.

An example here (albeit FW) would be my tanks. They are massiively overstocked by the 1" per gallon, or the surface area models, but the tanks are linked to huge wet dry systems and large sumps so can handle the nitrogenous waste to nitrates and water changes deal with the rest.

However, parasites are only the tip of the iceberg and many ailments are more directly linked to water quality such as lateral line diseases (and/or hole in the head), swim bladder issues, tail/fin rot, issues which cause dropsy like symptoms, etc. Again, in many cases these water quality issues can stem directly from overstocking.

Important point here: can stem from overstocking. My point made above (though perhaps poorly) is that we cannot be truly sure it is just the overstocking that causes the problem, so much as poor husbandry. Overstocking without an appropriate increase in care would perhaps be a better term (unless we have a fish that has no room to turn around).

So, in short, I would say yes, overstocking and the resulting side effects, whether theoretical or scientifically proven, can be blamed on a wide array of problems in fish.

This is sort of my point. there are too many variables to nail it on one thing.

This may be compounded in a marine tank due to the fact that the role of osmosis requires saltwater livestock to 'drink' more water than their freshwater counterparts, meaning that along with that water, the fish are also ingesting the unhealthy attributes included (perhaps the reason it is often suggested to stock much 'lighter' than in a FW tank?)

My understanding is not so much about the osmoregulatory processes as much as the fact that saltwater contains far less dissolved oxygen than FW and that many reefs contain invertebrates which are more susceptible to pollutants such as nitrates and such, somewhat in agreement with your ultimate paragraph. Somewhat interestingly, the science posted previously by Tom Barr indicates a lower limit of over 400 ppm before fish see any long or short term issues with nitrates.

 

[Tommy Gun]

An example here (albeit FW) would be my tanks. They are massiively overstocked by the 1" per gallon, or the surface area models, but the tanks are linked to huge wet dry systems and large sumps so can handle the nitrogenous waste to nitrates and water changes deal with the rest.

While I realize that I have often referred to freshwater situations, it is very true that the game does change in saltwater. Like you, I also have largely overstocked cichlid tanks and deal with the situation in the exact same methods you elude to; lots of water changes, wet/dry filters and sumps, and in one case, water trickles out of my 90 gallon tank while an auto top of system generates a sort of constant water change. However, I doubt I could afford such measures on my reef tank simply because I would probably run through buckets of salt in a week and a half.

In any case, I am sure you are as equally aware of the fact that any 'inch per gallon' rule or guideline is a farce and was never intended to apply to every fish, in fact, these days only applies to a tiny number of species.

My understanding is not so much about the osmoregulatory processes as much as the fact that saltwater contains far less dissolved oxygen than FW and that many reefs contain invertebrates which are more susceptible to pollutants such as nitrates and such, somewhat in agreement with your ultimate paragraph

This is why I think some of us have a skewed view point of osmosis. At its most basic definition, osmosis simply refers to the movement of water across a semi-permiable membrain which occurs when there is an inbalance between both sides (in reverse osmosis filtration, I believe the imbalance is pressure). With that in mind, since freshwater fish are more salty than the water they live in, in order to retain that much needed salt, they must not ingest a lot of water - hence they don't 'drink' water, so to speak. The reverse of that then is the fact that a marine fish's body is much less salty than the water it live in and so it needs to continually 'flush' water in and out of its body and expell the salt. (By 'ingest', I don't solely mean drinking water in the literal sense, although that could be part of it) So, this is one reason for the incresed 'sensitivity' towards water quality that is noticed in marine fishes. (I am just about to walk out the door for thanksgiving festivities part deux, so I will provide some good supporting resources later tonight....otherwise they can be found quite readily). In short, while I completely agree that dissolved oxygen is of importance within any type of water, it is getting a bit off topic from my origonal point.

Somewhat interestingly, the science posted previously by Tom Barr indicates a lower limit of over 400 ppm before fish see any long or short term issues with nitrates.

I agree with the idea that nitrates are not of major concern to fish within reason (i.e. there are extreme examples were as I am speaking of 'normal' operating conditions). However, this does not hold true for corals, anemones, and some clean up crew type inverts. Simple logic would help us realize that in many corals and all anemones, size is determined by the amount of water that is currently being held within the animal....perhaps anemones are the best example since, if you were to disturb one, they can quickly retract to only a fraction of its full potential size --- hence the more common advice that an anemones are best left at the LFS until we are experienced enough to deal with their needs, and when the tank has become established enough to be a more stable environment.

can stem from overstocking. My point made above (though perhaps poorly) is that we cannot be truly sure it is just the overstocking that causes the problem, so much as poor husbandry

My argument here is that stocking choices are husbandry. And in the case of a reef tank, overstocking can defeat the good husbandry efforts for maintaining corals when looking at the complete picture.

 

[andywg]

Slightly off topic of recent posts, but interesting regarding earlier posts on a fish's ability to adapt to changes:

Kelly Tarlton's (an Antarctic based aquatic display in Auckland New Zealand) were shown in a nature documentary receiving 2 baby bull sharks. To get the bull sharks in the tank quickly they were flown from their previous site. These bull sharks (each about 18" long) spent 6 hours in a 3 foot cube.

Acclimatisation?

They were put into a smaller polybox to carry them to the exhibit, netted and dumped straight into the larger tank. Surely if anyone is going to be aware of problems for fish it will be the marine biologists taking care of these fish, yet they performed no acclimatisation at all.

Now these fish are somewhat more varied and able to move from environ to environ, but that is quite a jump, especially as they were against the clock to stop the water temperature going too high.

Cause for thought? Perhaps so. I have frequently read of people doing less than 20 minutes of acclimatisation on fish (and then mostly for temp). I certainly agree inverts need more care due to the fact they are osmoconformists.

 

[andywg]

While I realize that I have often referred to freshwater situations, it is very true that the game does change in saltwater. Like you, I also have largely overstocked cichlid tanks and deal with the situation in the exact same methods you elude to; lots of water changes, wet/dry filters and sumps, and in one case, water trickles out of my 90 gallon tank while an auto top of system generates a sort of constant water change. However, I doubt I could afford such measures on my reef tank simply because I would probably run through buckets of salt in a week and a half.

But if one is near the sea one is only heating the water.

In any case, I am sure you are as equally aware of the fact that any 'inch per gallon' rule or guideline is a farce and was never intended to apply to every fish, in fact, these days only applies to a tiny number of species.

It is not a farce, it is a tough guide for new keepers to FW that allows some room for manoeuvre without causing too many extra issues. I do understand it is not applicable to any of the fish I keep, which is just as well because very few of my tanks will come in at under 2" per gallon.

This is why I think some of us have a skewed view point of osmosis. At its most basic definition, osmosis simply refers to the movement of water across a semi-permiable membrain which occurs when there is an inbalance between both sides (in reverse osmosis filtration, I believe the imbalance is pressure). With that in mind, since freshwater fish are more salty than the water they live in, in order to retain that much needed salt, they must not ingest a lot of water - hence they don't 'drink' water, so to speak. The reverse of that then is the fact that a marine fish's body is much less salty than the water it live in and so it needs to continually 'flush' water in and out of its body and expell the salt. (By 'ingest', I don't solely mean drinking water in the literal sense, although that could be part of it) So, this is one reason for the incresed 'sensitivity' towards water quality that is noticed in marine fishes. (I am just about to walk out the door for thanksgiving festivities part deux, so I will provide some good supporting resources later tonight....otherwise they can be found quite readily). In short, while I completely agree that dissolved oxygen is of importance within any type of water, it is getting a bit off topic from my origonal point.

I would be interested to see how the fish are more succeptible, they are certainly taking in more of the water going in and out, but there are other things to notice. Measurable ammonia is higher in SW as the raised pH of saltwater makes the ammonia/ammonium balance less in our favour.

Nitrites are said to be less toxic in FW with added salt (and this is hinted as being similar for brackish tanks). Does this perhaps carry true for SW? I honestly don't know.

As I mentioned, inverts are somewhat different as they are osmoconformists so their internal salt levels will be equal to the external levels (somewhat similar to hagfish IIRC).

However, this does not hold true for corals, anemones, and some clean up crew type inverts. Simple logic would help us realize that in many corals and all anemones, size is determined by the amount of water that is currently being held within the animal....perhaps anemones are the best example since, if you were to disturb one, they can quickly retract to only a fraction of its full potential size --- hence the more common advice that an anemones are best left at the LFS until we are experienced enough to deal with their needs, and when the tank has become established enough to be a more stable environment.

I do not dispute this, and have mentioned similar above that inverts are the main problem for water stats, not fish in a reef.

My argument here is that stocking choices are husbandry. And in the case of a reef tank, overstocking can defeat the good husbandry efforts for maintaining corals when looking at the complete picture.

But we don't know that it is the actual overstocking that is causing the problems. If someone is only slightly overstocked but doesn't do enough water changes then it is the water changes and not the overstocking that causes the problem.

Out of interest, when did we decide that all marine tanks are reefs? There is far more to SW than reefs, and my least favourite tank to keep involves inverts and corals. I thought we were more talking of marine tanks. There is quite a difference int he way I treat a FOWLR and a reef tank.

 

[Tommy Gun]

Slightly off topic of recent posts, but interesting regarding earlier posts on a fish's ability to adapt to changes:

Kelly Tarlton's (an Antarctic based aquatic display in Auckland New Zealand) were shown in a nature documentary receiving 2 baby bull sharks. To get the bull sharks in the tank quickly they were flown from their previous site. These bull sharks (each about 18" long) spent 6 hours in a 3 foot cube.

Acclimatisation?

They were put into a smaller polybox to carry them to the exhibit, netted and dumped straight into the larger tank. Surely if anyone is going to be aware of problems for fish it will be the marine biologists taking care of these fish, yet they performed no acclimatisation at all.

Now these fish are somewhat more varied and able to move from environ to environ, but that is quite a jump, especially as they were against the clock to stop the water temperature going too high.

Cause for thought? Perhaps so. I have frequently read of people doing less than 20 minutes of acclimatisation on fish (and then mostly for temp). I certainly agree inverts need more care due to the fact they are osmoconformists.

I do believe that it is cause for thought and please understand that I am in no way engaging in a "who is right" war with you, but I believe have found some possible answers to this mystery:

#1.) I read on the Kelly Tarlton's Antarctic Encounter and Underwater World web page that the Underwater World aquarium there - which sounds to be where they keep alot of different sharks, although I couldn't determine if they have bull sharks in it - not only holds One Million Liters of water, but is supplied directly from the Waitemata harbor which is salty so depending on where the bull sharks came from, perhaps the water was already the same in the first place.

#2.) Not having seen this myself, and I am certainly not accusing anyone of anything, but my initial doubt on what you have said here was simply that the documentary was almost certainly edited for time/content and so unless they blatantly point out that they did not acclimate the sharks, I don't know how anyone could come to a safe assumption that they weren't acclimated.

#3.) Last but definitely not least, what does seem to blow all but the most fragile abilities to construct a statement "If bull sharks can do it, certainly any fish can do it" is the fact that Bull Sharks are very much the exception to any acclimation rule, or so it would seem based upon the information provided on THIS WEBSITE. For those who do not want to read the entire blurb there, it basically focuses on how bull sharks have been found in the Mississippi River as far north as Illinois (which is getting close to the middle of the US) with the amazing part of that feat being the fact that the Mississippi is a freshwater river (an interesting side note is that the effects of the Mississippi River dumping freshwater into the Gulf of Mexico can literally be seen from space).

So, even though I am 99% sure that you are not trying to imply that acclimation theories are a complete farce, I still feel pretty justified in both my opinion regarding acclimation being a great safety precaution and that osmosis has a lot to do with the reason for doing so. In fact, even if I just brought a bull shark home, I would still acclimate it simply because it can help guard against the unknown and/or unseen. Additionally, I also have been in a rush to release a fish into my tank and did so within a half our or less, but I was also once told that I should never have to acclimate snails and for a long time, I couldn't keep one alive for more than a day or two so I became a strong advocate of this practice. As far as a previous debate with Lynden regarding any risks involved within acclimating for too long, I still disagree with much of that so long as the acclimation time period is within reason....which I would say is less than four hours and now understand that Lynden may feel as though 'within reason' is defined as around one hour, but definitely less than two; which I can accept that since that is just about how long I acclimate all but my most sensitive (read: expensive) livestock.

 

[Tommy Gun]

But if one is near the sea one is only heating the water.

Good point ---- obviously it didn't occur to me since I don't live by the sea. However, I do live close enough to a very large FW lake (Lake Michigan) that I could literally throw a rock at it and hit the water and have formed a distinct opinion that if I was to take water directly from the lake - meaning, before it passes through the water processing facility, which I could also hit with a rock, albeit a smaller one I am sure - I would be putting my fish in danger because of the possible pollutants that I could also be bringing home. Granted, the sea is a much larger body of water than a lake, however I have watched at least one great documentary (Blue Planet, I think) that pointed out how reefs are being affected by human-based polution....in fact, I believe that one hypothesis for the swelling of the harmful crown of thorns sea star population was run off or other pollutants so that might also provide some risk for using sea water in an aquarium. Obviously, if you were to filter out any possible pollutants, then you would most likely wind up with freshwater anyways, so the cost of extremely frequent water changes is probably back in play. Besides, this is all not to mention the other issues that could inadvertently find their way into an aquarium (e.g. ich).

It is not a farce, it is a tough guide for new keepers to FW that allows some room for manoeuvre without causing too many extra issues. I do understand it is not applicable to any of the fish I keep, which is just as well because very few of my tanks will come in at under 2" per gallon.

I still disagree though, and refer to the rule as a farce for quite a few reasons including, but not limited to:

1. By many accounts, the freshwater version only applies to fish which reach a maximum length of 3 inches and those which have the similar body shape of a neon tetra

2. The 'rule' can be misunderstood to imply that one can keep a 10 inch fish in a 10 gallon tank

3. It can easily be argued that one 10 inch fish would produce a lower amount of waste than having ten 1 inch fish - with some exceptions, I know.

4. The 'rule' does not account for the fact that some fish are more 'messy' than others. For example, many herbivorous fish need to eat copious amounts of veggie matter in order to gain sufficient levels of nutrition and in turn, produce more wastes than they otherwise might. Additionally, I have read/heard that many of the 'predator' type fish such as the lionfish also produce a higher amount of wastes due to their diet (eat a lot at one time)....but cannot remember where I got that idea from right now.

5. While it is certainly not the "rule's" fault, many hobbyists seem to forget that the rule applies to a fish's full potential size and not the size at time of purchase.

6. The "rule" does not take into account the presence of plants, both freshwater and saltwater (macro algae), nor does the saltwater version take into account the presence of coral, anemones, and/or amount of live rock, or lack thereof.

7. The "rule" does not take into account the method and/or amount of filtration (e.g. a wet/dry filter and/or sump would add water volume to the system

8. The "rule" is solely focused on volume of water, not the tank size or shape. For example, someone might have a 20 gallon aquarium and feel as though he/she can fit ten to twenty inches of fish in it but does not consider that some fish need a larger 'footprint', some need more swimming room, and some might need more space in order to turn around, among other factors which could lead to buying the wrong fish even though it is the right size.

9. Expanding upon #8, since the 'rule' is solely focused on water volume, it theoretically implies that I could fit nearly 100 inches of fish in my saltwater tank because I have a sump and refugium which add water volume even though the tank is not nearly large enough to hold all of those potential fish comfortably.

....I am sure you get my drift. To be honest, I can see that the 'rule' has great intentions and like I eluded to earlier, was probably much more applicable a few decades ago when the variety of fish being kept was much smaller today but many of the fish we can keep now are those which bust this rule. Personally, I feel that since the 'rule' does have so many exceptions today, it would be best to throw it out completely and look at each stocking option on a case by case basis in order to best determine what we can or cannot keep within our tank(s). Make sense?

I would be interested to see how the fish are more susceptible, they are certainly taking in more of the water going in and out, but there are other things to notice.

Not to insult your intelligence or anything but my comments haven't really focused too much on how much water enters a fish via its mouth per say, but more on a cellular level --- although drinking water in a literal sense does play some role here.

Hopefully you can accept this as a reliable or scientific based resource since it is from a college, but this is one of the shorter, more easy to understand blurbs to support my notion that more water is used within our SW fish and in fact, points out that SW fish literally drink water via their mouths - which supports the idea that they are more prone to being affected by the surrounding water's chemistry (both good and bad) - where as freshwater fish do not do this:

[URL="http/amos.indiana.edu/library/scripts/fishdrink.html"]http/amos.indiana.edu/library/scripts/fishdrink.html[/URL]
-----
While not any sort of proof, but here is a link to a learning excessive (experiment) that one can do in order to see visual evidence of how "osmotic goals" differ in freshwater and saltwater fish.

[URL="http/www.dfo-mpo.gc.ca/canwaters-eauxcan...ties/act1_e.asp"]http/www.dfo-mpo.gc.ca/canwaters-eauxcan...ties/act1_e.asp[/URL]
-----
Again, this link may not lead to purely scientific proof of my points thus far because it looks to be an essay written by a student of some sort, but I think it does show that this is a relatively common ideology if nothing else (picked this one for you Lynden! She is from Canada):

[URL="http/www.netera.ca/essays/Ashley_Kellsey-Shoemaker.pdf"]http/www.netera.ca/essays/Ashley_Kellsey-Shoemaker.pdf[/URL]
--------
A small blurb which answers a question regarding if and how a SW fish would die if placed in freshwater, and vice versa

[URL="http/www.saltwater-aquarium-guide.com/Fa...acts-page17.htm"]http/www.saltwater-aquarium-guide.com/Fa...acts-page17.htm[/URL]
-------
Here is another one aimed directly at Lynden, but also points out some information on why saltwater fish are more sensitive than freshwater fish - but the reason it is pointed at Lynden is because, if you scroll down to the middle of the page, you can find a list of various saltwater fish which includes mollies AND points out that one can acclimate a molly to a marine environment over a period of 6 to 8 hours, not instantly:

[URL="http/fishandexotics.tripod.com/id18.htm"]http/fishandexotics.tripod.com/id18.htm[/URL]
------

===========================
SIDENOTE (before I forget): If you feel as though the 'inch per gallon rule' is a reliable guideline for stocking a tank, what is the reasoning for it stating that 1 inch of fish per gallon is good in freshwater, but then becomes more stringent by, depending on who you ask, stating that one inch of fish per every two gallons of water is best for salty tanks? Could this variance also support the notion that saltwater fish are more sensitive and hence, overstocking could be a more dire situation in this case versus freshwater?
===========================

I am sure you can understand that I could post quite a few more resources on this topic, but I don't want to throw up anything that I feel is too questionable in order to avoid my point getting lost along the way.

Measurable ammonia is higher in SW as the raised pH of saltwater makes the ammonia/ammonium balance less in our favour.

Measurable ammonia is higher in SW because of the pH, yes. HOWEVER, this is a mute point in a cycled tank, right?

Couple questions for anyone who can satisfy my curiousity....

1. To the best of my understanding right now, nitrites are toxic to freshwater fish because they bond with the hemoglobin in the blood which inhibits the amount of oxygen the blood can carry and one method of helping defeat that is to add some salt to the water since it inhibits the ability of nitrite to bond with the blood....so what is the case in saltwater fish? I understand that there are huge differences between the salt being suggested for a FW tank (NaCl) and marine salt, but I am curious to know if nitrites play a different role in SW or if that remains the same.

2. Again, to the best of my understanding, the products (e.g. some dechlor conditioners like Prime, I believe) which are able to, or claim that they are able to remove ammonia from water do so by 'transforming' ammonia into ammonium --- I am curious to know how this is done exactly and how long the ammonium can remain in this form before it once again becomes ammonia (if it does) when the pH of the tank is above 7.0?

I do not dispute this, and have mentioned similar above that inverts are the main problem for water stats, not fish in a reef.

Sorry if I implied that you were disputing this, I didn't mean to. however, I have to admit my confusion again because the reason I brought that up was in reference to those who overstock a reef tank with my point being the fact that, even if the fish can 'deal with' the more rapidly degrading water quality, the corals are being affected from it -- or to imply that it would be 'safer' to overstock a FOWLR or fish-only tank versus a reef even though I wouldn't really suggest doing either for the other reasons I mentioned (mainly, saltwater fish use a lot of their surrounding water within their bodies and hence, are affected by bad water parameters more readily).

But we don't know that it is the actual overstocking that is causing the problems. If someone is only slightly overstocked but doesn't do enough water changes then it is the water changes and not the overstocking that causes the problem.

True, very true. However, we can try to push blame around all day and not gain any ground, right? However, if we look at the true cause and effect scenario, it is the overstocking which causes the need for more frequent or larger water changes since the opposite would make no sense: I have to overstock because I do too large or too many water changes.

In the end, the point still remains, overstocking and/or insufficient water changes (among other things) are at least a good thing to avoid, right?

Out of interest, when did we decide that all marine tanks are reefs? There is far more to SW than reefs, and my least favorite tank to keep involves inverts and corals. I thought we were more talking of marine tanks. There is quite a difference int he way I treat a FOWLR and a reef tank.

I know that and have one of each myself (FOWLR and reef) and approach them differently in some aspects. However, don't forget that this conversation began with a debate over Lynden's stocking (IMHO, overstocking) in his 33 gallon reef tank. That being said, I still have a hard time believing that you might try to 'defend' those choices - which I get the feeling you were by pointing out how fish cannot be 'stunted' (remember, he has some potentially very large fish in a 33 gallon tank) and more recently by seeming to say that overstocking is hard to do or can be overcome in his situation (I think that came out of my "will the eels really reach two feet long in that tank?") ---- which, in rebuttal, I have to disagree because overstocking can lead to quickly degrading water quality (which affects corals and anemones more than fish) and that keeping that many fish, which could potentially become very large fish/eels, in such a small tank will lead to problems....and haven't even touched other reasons such as cramped conditions can lead to aggression issues in even the more docile livestock yet.

===============
LEGAL DISCLAIMER:

Lynden, please please please understand that my intentions here are NOT NOT NOT completely focused on your or your tank so please don't feel as though you have to be overly defensive. My point here is simply to discuss these topics because

A. They help build support for some of my points within other debates we have been involved in.

B. They may serve to help others who are just starting out in saltwater, especially those who want to start with a nano-tank, by emphasizing some of the reasons behind what I feel are the more common pieces of advice that are given out on forums like this one.

So, while I realize that it may not sound like it, I am simply using your current situation as an example, and with all due respect, realize that you are taking the extra steps and additional work required to keep your tank thriving, as well as knowing that you are working on setting up some larger tanks so the situation is probably not permanent at all. As I have recently proven to you, I am open to your ideas and points, otherwise I wouldn't have a porcupine puffer in my reef tank right now, and I would hate for you to feel as though I am being combative with you. Honestly.

EDIT: My 6 year old can spell better than I can tonight

 

[Lynden]

So, while I realize that it may not sound like it, I am simply using your current situation as an example, and with all due respect, realize that you are taking the extra steps and additional work required to keep your tank thriving, as well as knowing that you are working on setting up some larger tanks so the situation is probably not permanent at all. As I have recently proven to you, I am open to your ideas and points, otherwise I wouldn't have a porcupine puffer in my reef tank right now, and I would hate for you to feel as though I am being combative with you. Honestly.

Honestly I don't mind at all. I openly admit my tank is overstocked though you are correct that I have taken special precautions and that I have bigger tanks to be set up.

 

[andywg]

I do believe that it is cause for thought and please understand that I am in no way engaging in a "who is right" war with you, but I believe have found some possible answers to this mystery:

#1.) I read on the Kelly Tarlton's Antarctic Encounter and Underwater World web page that the Underwater World aquarium there - which sounds to be where they keep alot of different sharks, although I couldn't determine if they have bull sharks in it - not only holds One Million Liters of water, but is supplied directly from the Waitemata harbor which is salty so depending on where the bull sharks came from, perhaps the water was already the same in the first place.

Though as the sharks needed somewhere in the region of a 3 hour or more flight, it is likely to be some distance.

#2.) Not having seen this myself, and I am certainly not accusing anyone of anything, but my initial doubt on what you have said here was simply that the documentary was almost certainly edited for time/content and so unless they blatantly point out that they did not acclimate the sharks, I don't know how anyone could come to a safe assumption that they weren't acclimated.

Indeed it could, though the fact they merely showed getting the container near the building and then throwing the sharks into a box and then into the tank makes me wonder where and how any acclimatisation would take place.

#3.) Last but definitely not least, what does seem to blow all but the most fragile abilities to construct a statement "If bull sharks can do it, certainly any fish can do it"

But who has actually said that? I distinctly put in that bull sharks are somewhat varied in their environments but stated it agreed with the advice in many places that fish do not need the long 2-4 hour drip acclimatisation that many inverts do.

Additionally, I also have been in a rush to release a fish into my tank and did so within a half our or less, but I was also once told that I hould never have to acclimate snails and for a long time, I couldn't keep one alive for more than a day or two so I became a strong advocate of this practice.

But as I stated (and you would appear to agree) osmoregulation is an important part of the acclimatisation. Almost all innvertebrates are osmoconformists, so do not have any sort of buffer provided by kidneys and the such. I certainly agree that inverts do require long acclimatisation, but I do not believe fish need such lengthy periods.

 

[andywg]

however I have watched at least one great documentary (Blue Planet, I think) that pointed out how reefs are being affected by human-based polution....in fact, I believe that one hypothesis for the swelling of the harmful crown of thorns sea star population was run off or other pollutants so that might also provide some risk for using sea water in an aquarium. Obviously, if you were to filter out any possible pollutants, then you would most likely wind up with freshwater anyways, so the cost of extremely frequent water changes is probably back in play. Besides, this is all not to mention the other issues that could inadvertently find their way into an aquarium (e.g. ich).

A simple UV on the inlet would stop those problems. I seem to recall pictures of a man living in South East Asia who had such a tank (around 1,900 gallons) which basically had almost no filtration but piped sea water straight in and straight back out.

I still disagree though, and refer to the rule as a farce for quite a few reasons including, but not limited to:
...

....I am sure you get my drift. To be honest, I can see that the 'rule' has great intentions and like I eluded to earlier, was probably much more applicable a few decades ago when the variety of fish being kept was much smaller today but many of the fish we can keep now are those which bust this rule. Personally, I feel that since the 'rule' does have so many exceptions today, it would be best to throw it out completely and look at each stocking option on a case by case basis in order to best determine what we can or cannot keep within our tank(s). Make sense?

It is not a rule, but a guideline, and it has great uses. How do you quickly explain to someone how to set up their tank without baffling them with terms of bio load, nitrate accumulation and maintenace regime? You tell them to stock with smaller fish at a rate of around 1" per gallon. Then once they learn more they can start to forget the rule and figure their own stocking.

Not to insult your intelligence or anything but my comments haven't really focused too much on how much water enters a fish via its mouth per say, but more on a cellular level --- although drinking water in a literal sense does play some role here.

But I was after exactly how they are more likely to be affected. Many people claim nitrates should be less than 10ppm in a marine tank (including one of your links) yet the scientific texts say 400ppm.

Hopefully you can accept this as a reliable or scientific based resource since it is from a college, but this is one of the shorter, more easy to understand blurbs to support my notion that more water is used within our SW fish and in fact, points out that SW fish literally drink water via their mouths - which supports the idea that they are more prone to being affected by the surrounding water's chemistry (both good and bad) - where as freshwater fish do not do this:

<a href="http/amos.indiana.edu/library/scripts/fishdrink.html" target="_blank">http/amos.indiana.edu/library/scripts/fishdrink.html</a>

Sadly I can't. That is just a text saying fish drink through their mouth. It says nothing about how the mere fact they are drinking the water makes them more susceptible to any problems.

-----
While not any sort of proof, but here is a link to a learning excessive (experiment) that one can do in order to see visual evidence of how "osmotic goals" differ in freshwater and saltwater fish.

<a href="http/www.dfo-mpo.gc.ca/canwaters-eauxcan...ties/act1_e.asp" target="_blank">http/www.dfo-mpo.gc.ca/canwaters-eauxcan...ties/act1_e.asp</a>

Again, you are merely showing me osmosis, not how the differing method of osmosis actually make the fish more susceptible in an aquarium setting to the parameters we encounter.

-----
Again, this link may not lead to purely scientific proof of my points thus far because it looks to be an essay written by a student of some sort, but I think it does show that this is a relatively common ideology if nothing else (picked this one for you Lynden! She is from Canada):

<a href="http/www.netera.ca/essays/Ashley_Kellsey-Shoemaker.pdf" target="_blank">http/www.netera.ca/essays/Ashley_Kellsey-Shoemaker.pdf</a>

Written by someone in Junior High from details they found on the internet. I take issue with FW fish blowing up like a balloon as it is more likely they would just lose all their internal salts to the point that their cells and biological functions would no longer work.

--------
A small blurb which answers a question regarding if and how a SW fish would die if placed in freshwater, and vice versa


<a href="http/www.saltwater-aquarium-guide.com/Fa...acts-page17.htm" target="_blank">http/www.saltwater-aquarium-guide.com/Fa...acts-page17.htm</a>

But not how the mere fact they are in SW makes them more susceptible to any ammonia/nitrite/nitrate in the water

-------
Here is another one aimed directly at Lynden, but also points out some information on why saltwater fish are more sensitive than freshwater fish - but the reason it is pointed at Lynden is because, if you scroll down to the middle of the page, you can find a list of various saltwater fish which includes mollies AND points out that one can acclimate a molly to a marine environment over a period of 6 to 8 hours, not instantly:

<a href="http/fishandexotics.tripod.com/id18.htm" target="_blank">http/fishandexotics.tripod.com/id18.htm</a>

That is just their advice. nmonks states :

"Mollies, by contrast, can be almost dumped into seawater from a freshwater tank without problems."

From this post

---EDIT----

Just noticed this recent post from neale:

"Anyway, you can acclimate mollies from fresh to salt, or vice versa, in about an hour"

---END EDIT---

Whom do you believe, a random website, or someone with the brackish experience and knowledge of nmonks? Almost all euryhaline fishes can be moved from FW to SW in a short time. The problem for most of us (and the reason we change our tanks slowly) is the filter bacteria is not euryhaline, being as it is an osmoconformist and not an osmoregulator and as such must be moced slowly to allow lower slainity bacteria to die and be replaced at a safe rate by higher salinity bacteria (or vice versa).

Also, that site hasn't read a great deal of science before posting as they claim nitrates should stay below 10ppm. In a reef tank I would not disagree, but the scientific papers indicate 400ppm is the safe lower level for nitrates for fish.

===========================
SIDENOTE (before I forget): If you feel as though the 'inch per gallon rule' is a reliable guideline for stocking a tank, what is the reasoning for it stating that 1 inch of fish per gallon is good in freshwater, but then becomes more stringent by, depending on who you ask, stating that one inch of fish per every two gallons of water is best for salty tanks? Could this variance also support the notion that saltwater fish are more sensitive and hence, overstocking could be a more dire situation in this case versus freshwater?
===========================

It could. It could also be because marine water contains somewhere around 42% less dissolved oxygen than freshwater and as such there will only be enough oxygen to support half the fish.

I am sure you can understand that I could post quite a few more resources on this topic, but I don't want to throw up anything that I feel is too questionable in order to avoid my point getting lost along the way.

No problems, just post something that is of a more scientific nature that does not prove that marine fishes take on water rather than retain it, but exactly how this will make them more susceptible to any pollutants. At the end of the day, FW fish are still living in the water, and will still be taking water into their bodies.

From my reference books, it would seem that freshwater fish are ingesting large amounts of water, but they do so passively across the gills (rather than actively through ingesting the water into the digestive system). This water is then turned into dilute urine which is continually produced to expel the excess water (Moyle and Cech, Fishes: An Introduction to Ichthyology, 5th edition - p 99).

The notion of fish "drinking" water is a misnomer. FW fish don't need to drink water as it is constantly pushed into their body at the gills and (to a lesser extent) their skin. However, some freshwater teleosts do drink water, despite the added burden this will place on their kidney at having to rid the excess water (Evans, 1980).

So on the above, I am not so sure that SW fish are so susceptible to pollutants, as the SW fish are keeping the water and trying to kick everything else out, while FW fish are getting rid of the water but trying to keep back the dissolved salt therein.

I think shall place a topic on this in the science section (please understand it is not something against you personally) as it could prove an interesting point (and that area has laid somewhat dormant in terms of decent discussions lately). I would be interested to see more into this and whether it is somewhat of a myth that SW fish are more susceptible to water conditions because of their osmoregulatory functions.

 

[andywg]

Measurable ammonia is higher in SW because of the pH, yes. HOWEVER, this is a mute point in a cycled tank, right?

Hopefully, but one would say to stock lighter to reduce the chances of ammonia spikes, having one where far more of the measured amount is dangerous will be worse, so one would advise to stock lighter.

Couple questions for anyone who can satisfy my curiousity....

1. To the best of my understanding right now, nitrites are toxic to freshwater fish because they bond with the hemoglobin in the blood which inhibits the amount of oxygen the blood can carry and one method of helping defeat that is to add some salt to the water since it inhibits the ability of nitrite to bond with the blood....so what is the case in saltwater fish? I understand that there are huge differences between the salt being suggested for a FW tank (NaCl) and marine salt, but I am curious to know if nitrites play a different role in SW or if that remains the same.

I would expect the compound to react in the same way, but I am unsure, I shall include this as part of the scientific forum debate. I would love to find out more on this as we are now essentially questioning some of the basic blocks of information given to us, but seldom actually proved.

2. Again, to the best of my understanding, the products (e.g. some dechlor conditioners like Prime, I believe) which are able to, or claim that they are able to remove ammonia from water do so by 'transforming' ammonia into ammonium --- I am curious to know how this is done exactly and how long the ammonium can remain in this form before it once again becomes ammonia (if it does) when the pH of the tank is above 7.0?

I have no idea how long the bonding would last. I know the bonding is not permanent as the resultant compound is available for the filter bacteria to utilise.

Sorry if I implied that you were disputing this, I didn't mean to. however, I have to admit my confusion again because the reason I brought that up was in reference to those who overstock a reef tank with my point being the fact that, even if the fish can 'deal with' the more rapidly degrading water quality, the corals are being affected from it -- or to imply that it would be 'safer' to overstock a FOWLR or fish-only tank versus a reef even though I wouldn't really suggest doing either for the other reasons I mentioned (mainly, saltwater fish use a lot of their surrounding water within their bodies and hence, are affected by bad water parameters more readily).

As noted above, FW fish use a lot of the surrounding water too in that it passes into the body and then back out, just like with marine teleosts, only marine teleosts take it in through the mouth and out at the gills, FW take it in at the gills and out through urine.

True, very true. However, we can try to push blame around all day and not gain any ground, right? However, if we look at the true cause and effect scenario, it is the overstocking which causes the need for more frequent or larger water changes since the opposite would make no sense: I have to overstock because I do too large or too many water changes.

In the end, the point still remains, overstocking and/or insufficient water changes (among other things) are at least a good thing to avoid, right?

Undoubtedly

That being said, I still have a hard time believing that you might try to 'defend' those choices - which I get the feeling you were by pointing out how fish cannot be 'stunted' (remember, he has some potentially very large fish in a 33 gallon tank) and more recently by seeming to say that overstocking is hard to do or can be overcome in his situation (I think that came out of my "will the eels really reach two feet long in that tank?") ---- which, in rebuttal, I have to disagree because overstocking can lead to quickly degrading water quality (which affects corals and anemones more than fish) and that keeping that many fish, which could potentially become very large fish/eels, in such a small tank will lead to problems....and haven't even touched other reasons such as cramped conditions can lead to aggression issues in even the more docile livestock yet.

Indeed.