Gravel Question

[Narwoo]

Can I use the gravel from my saltwater tank if I thouroughly wash and clean it and ensure that there is no residual salt left? How about the formerly live rocks?
Thank you

 

[Byron]

If you mean use it again in a marine tank, I would think so, but I have no experience with marine (salt) tanks. Also no knowlkedge of live rock (I know what it is but no idea outside a marine tank).

If you mean in a freshwater aquarium, no. Aside from the salt which is an issue, this substrate might be intended for marine tanks and be calcareous which could wreak havoc with some freshwater fish. There could be pathogens too.

 

[Narwoo]

If you mean use it again in a marine tank, I would think so, but I have no experience with marine (salt) tanks. Also no knowlkedge of live rock (I know what it is but no idea outside a marine tank).

If you mean in a freshwater aquarium, no. Aside from the salt which is an issue, this substrate might be intended for marine tanks and be calcareous which could wreak havoc with some freshwater fish. There could be pathogens too.

Thanks, but I think I need some more input. If you read my post you will notice that I specifically menetioned that there would be NO salt. And no organics of any kind. Is calcium really that toxic to freshwater fish? What happends when a snail or clam or lobster dies. Lots of calcium in those remains - especially the shells which most don't throw out.

 

[Colin_T]

Live rock is simply limestone, sandstone and dead coral that has been in a marine aquarium for more than 3 months and has microscopic organisms and bigger life forms living on it.

Marine sand is usually calcium based, as is the live rock.

------------------------
If you plan on keeping freshwater fishes that come from hard alkaline water, then yes you can use the rock and sand. However, if you plan on keeping soft water fishes, then no you can't.

Fish that naturally occur in hard alkaline water include: African Rift Lake cichlids, livebearers (mollies, platies, guppies, swordtails), rainbowfish, goldfish.

Fish that naturally occur in soft water include: angelfish, discus, Bettas, gouramis, barbs, tetras, Corydoras.

 

[Byron]

Is calcium really that toxic to freshwater fish? What happends when a snail or clam or lobster dies. Lots of calcium in those remains - especially the shells which most don't throw out.

You should not be keeping clams or lobsters in a freshwater fish tank, meaning a freshwater tank with freshwater fish in it. On their own it doesn't matter. As for snails, the level of calcium dissolving from the shell of a snail is so miniscule I doubt it would even be possible to measure it scientifically. Certainly not with our aquarium GH/KH test kits. By contrast the calcium and magnesium dissolving from a calcareous substrate will raise the GH/KH/pH very noticeably.

I have very soft water, basically zero GH/KH (officially it is 7 ppm which is less than half of one degree). I have snails in all my tanks and they die but the GH/KH remains zero and has for over a decade. When I was buffering the pH in my 90g tank some years ago, I used three tablespoons of crushed coral and aragonite marine gravel substrate placed in a nylon bag in the canister filter, and the pH rose from 6.2 up to 7.8 within 24 hours. That is a significant rise occurring from a miniscule amount of substrate, imagine a whole tank of it.

As for the effect on freshwater fish, as Colin mentioned this can be serious for soft water species. I referenced "for some species" previously with this in mind. Coming from a marine tank background, you may not be aware of the fundamental difference in fish physiology between marine and freshwater species pertaining to the water parameters/chemistry. All species of fish that live in the oceans are designed to function in the same water with respect to the parameters of GH, KH and pH. Freshwater is obviously different from ocean water but it is much more complicated than the basic obvious difference of salt. The freshwater of every region on the planet is unique to that region. This is because water is the universal solvent; as "pure" water falls as rain/snow it assimilates substances it comes into contact with, such as CO2 in the air causing more acidic water, minerals when it flows through rock formations, and organics such as wood, leaves, plant matter. This solvency makes the water chemically unique to that region.

Each species of freshwater fish on earth has evolved to function in the very specific parameters relevant to each environmental region. The physiology of the fish is different, and as soon as the fish is placed in an aquatic environment different from that for which it is designed, it has trouble functioning. This is why members here always ask for the GH and pH of the source water before suggesting suitable fish for a member's aquarium. Fish cannot adapt quickly, when it has taken thousands of years for them to be uniquely suited to very specific environment which has to do with water parameters, habitat, and sympatric species.

A study on the cardinal tetra, Parachierodon axelrodi, carried out in Germany some years back determined that the lifespan of this softwater fish was relevant to the GH of the water in which it was living; the harder the water, the shorter the lifespan. Necropsies of the dead fish showed calcium blockage of the kidneys as the cause of death; the more calcium in the water, the shorter the lifespan because the fish simply cannot cope with this because it is not built to deal with such differences in its aquatic environment. So yes, a calcareous substrate has an immense impact on the fish, depending upon species. If we want our fish to live healthy normal lives, we must understand their needs and provide for them.

 

[Back in the fold]

You should not be keeping clams or lobsters in a freshwater fish tank, meaning a freshwater tank with freshwater fish in it. On their own it doesn't matter. As for snails, the level of calcium dissolving from the shell of a snail is so miniscule I doubt it would even be possible to measure it scientifically. Certainly not with our aquarium GH/KH test kits. By contrast the calcium and magnesium dissolving from a calcareous substrate will raise the GH/KH/pH very noticeably.

I have very soft water, basically zero GH/KH (officially it is 7 ppm which is less than half of one degree). I have snails in all my tanks and they die but the GH/KH remains zero and has for over a decade. When I was buffering the pH in my 90g tank some years ago, I used three tablespoons of crushed coral and aragonite marine gravel substrate placed in a nylon bag in the canister filter, and the pH rose from 6.2 up to 7.8 within 24 hours. That is a significant rise occurring from a miniscule amount of substrate, imagine a whole tank of it.

As for the effect on freshwater fish, as Colin mentioned this can be serious for soft water species. I referenced "for some species" previously with this in mind. Coming from a marine tank background, you may not be aware of the fundamental difference in fish physiology between marine and freshwater species pertaining to the water parameters/chemistry. All species of fish that live in the oceans are designed to function in the same water with respect to the parameters of GH, KH and pH. Freshwater is obviously different from ocean water but it is much more complicated than the basic obvious difference of salt. The freshwater of every region on the planet is unique to that region. This is because water is the universal solvent; as "pure" water falls as rain/snow it assimilates substances it comes into contact with, such as CO2 in the air causing more acidic water, minerals when it flows through rock formations, and organics such as wood, leaves, plant matter. This solvency makes the water chemically unique to that region.

Each species of freshwater fish on earth has evolved to function in the very specific parameters relevant to each environmental region. The physiology of the fish is different, and as soon as the fish is placed in an aquatic environment different from that for which it is designed, it has trouble functioning. This is why members here always ask for the GH and pH of the source water before suggesting suitable fish for a member's aquarium. Fish cannot adapt quickly, when it has taken thousands of years for them to be uniquely suited to very specific environment which has to do with water parameters, habitat, and sympatric species.

A study on the cardinal tetra, Parachierodon axelrodi, carried out in Germany some years back determined that the lifespan of this softwater fish was relevant to the GH of the water in which it was living; the harder the water, the shorter the lifespan. Necropsies of the dead fish showed calcium blockage of the kidneys as the cause of death; the more calcium in the water, the shorter the lifespan because the fish simply cannot cope with this because it is not built to deal with such differences in its aquatic environment. So yes, a calcareous substrate has an immense impact on the fish, depending upon species. If we want our fish to live healthy normal lives, we must understand their needs and provide for them.

Byron, you state that each species of fish functions in very specific water parameters. That is my understanding as well and I always have greater success with fish when I cater to their very specific water requirements. However, I have heard the statement that fish that have been in the hobby for many years and being captive bred in aquariums for many generations have permanently acclimated to "American" water. That just doesn't sound right to me. What say you ?

 

[seangee]

However, I have heard the statement that fish that have been in the hobby for many years and being captive bred in aquariums for many generations have permanently acclimated to "American" water.

I don't believe that. May be different in America but in Europe most captive bred fish are sourced from Asia anyway. I suspect that the percerption exists because the stronger specimens are the ones that survive. A few generations is not enough for evolutionary change.

I have not studied this but I do keep tetra (soft water fish). Where I live the water is very hard. About 18 months ago I decided to change my water. My own observation is that my captive bred tetra are much brighter and larger now than they were were before now that they are in soft water. They also spawn more frequently (in fact they never used to do this at all).

My observations are not scientific and its too early to tell. But before I switched to soft water I firmly believed that tetra lived for about 2 years and was regularly replenishing stock. These fish weren't sick, they were simply dying of old age (a.k.a. organ failure). I have only lost one fish in 18 months and that was over a year ago. Just because people are able to keep fish in water which is different to their natural habitat does not mean that the fish have adapted to those conditions. It simply means they are able to survive them - albeit for a limited period.

That's my take on it anyway.

 

[Byron]

Seangee is right on the mark...there is a difference between fish surviving and fish thriving. We should recognize that we are not going to change a fish's physiology in a few years or even a few decades when that species has evolved over thousands of years. Evolution is not simply an organism adapting to change; for a fish to evolve the change must somehow improve its chances of survival and be worth the effort. When you consider the physiology of a fish, how incredibly connected the fish is to its aquatic environment in ways not found in terrestrial animals (amphibians being an exception), you can understand that the fish is just not going to be able to realistically adapt to hard water if it is a soft water species. It may be forced to survive and to our perception may "seem" to be doing so successfully, but this is as far as it goes. Those species that have been more successful at this generally have reasons we can recognize that allow them to do so.

Generations of tank-raising fish has, not surprisingly, produced fish that are genetically weaker, physiologically weaker, and thus more susceptible to disease and genetic defects. Species that have not been tampered with by selective breeding to develop brighter colours but merely tank-raised for generations are frequently less colourful than their wild counterparts, and that is not accidental. I always attempt to acquire wild caught fish when I have the option because they are in better health, stronger, and usually brighter colouration.

 

[seangee]

Species that have not been tampered with by selective breeding to develop brighter colours but merely tank-raised for generations are frequently less colourful than their wild counterparts, and that is not accidental.

Now that is interesting. Part of my decision to create a "better" environment for my tetras was when my LFS got in a shipment of wild caught cardinals. They do have a soft water section, although it is a fairly small section as the water around London is well suited for walking on . The manager took me to see them and the difference between those and the regular stock in the hard water section was quite remarkable in terms of colouration and general appearance.

My original goal was to reduce my GH from 16 to 12 degrees (over a period of a few months) as this was the top end of what SF cites as the acceptable range for most of the species in my community tank. I have subsequently reduced again to 6 degrees and finally to 2, which is where the tank is now. I cannot quantify or prove this, but my perception is that my fish are now noticeably brighter which suggests that the loss of colouration is not all down to captive breeding.

 

[Byron]

Now that is interesting. Part of my decision to create a "better" environment for my tetras was when my LFS got in a shipment of wild caught cardinals. They do have a soft water section, although it is a fairly small section as the water around London is well suited for walking on . The manager took me to see them and the difference between those and the regular stock in the hard water section was quite remarkable in terms of colouration and general appearance.

My original goal was to reduce my GH from 16 to 12 degrees (over a period of a few months) as this was the top end of what SF cites as the acceptable range for most of the species in my community tank. I have subsequently reduced again to 6 degrees and finally to 2, which is where the tank is now. I cannot quantify or prove this, but my perception is that my fish are now noticeably brighter which suggests that the loss of colouration is not all down to captive breeding.

Both observations concur with the scientific-based information. Wild caught fish obviously will react more to inappropriate water because they are having to work much harder just to maintain their essential internal functions. I have frequently cited a good comparison I read in TFH some years back: it takes "x" energy to maintain a speed of 50 km/h driving a car; once you head up an incline, you need considerably more energy to maintain that speed. So it is with fish forced into water that they are simply not built to function in; it takes so much more energy they weaken generally, and the lack of colour is a sign of this.

 

[Back in the fold]

Gentlemen, your take on my question confirms what I only suspected. I have always felt that the water they naturally come from is best and you have confirmed that. Thank you for your well thought out comments, they are appreciated.

 

[FishGuest5123]

“American Water”, huh? Do they realize how large America is, anyway? We have so many different types of water and sources that no fish could acclimate to all even after many generations. Kind of a crazy statement, isn’t it?

 

[The Lumpfish Guy]

A study on the cardinal tetra, Parachierodon axelrodi, carried out in Germany some years back determined that the lifespan of this softwater fish was relevant to the GH of the water in which it was living; .

I'd be interested to see this study if you have the reference Byron?
I'll be honest, I am not convinced at the importance of hardness for most ornamentals. mainly due to the lack of peer reviewed published data. I have a long list of reasons, but I wont get into it into this thread, as we will go way off topic.

And just as an FYI significant population genetic change can happen over a very small number of generations.
Take guppy selection, It can only take me 10-20 generations to completely eliminate one tail colour or shape from that population gene pool.

What you are confusing is Specation- which occurs over a longer period of time, and is the formation of two distinct species.
Again take the guppies, I may have eliminated a tail colour or shape, but my altered population and my original populations can still interbreed and thus are still considered the same species.

 

[PheonixKingZ]

This is a very informative thread!

 

[Byron]

The German study was reported in Tropical Fish Hobbyist, August 1987, pp. 66-87. "Ecology of the Cardinal Tetra, Paracheirodon axzelrodi (Pisces, Characoidea), in the River Basin of the Rio Negro, Brazil, as well as Breeding-related Factors," by Rolf Geisler and Sergio R. Annibal [English translation of original German article].

Jacques Gery said that the cardinal tetra rarely lives more than a few years and this is solely because of the hardness of the water. Kept in very soft water it will easily live beyond ten years. That says it all. But the following excerpts summarize things, from The Manual of Fish Health authored by four acknowledged authorities in the field, Dr. Chris Andrews, Dr. Peter Burgess, Dr. Neville Carrington and Adrian Exell.

Water hardness affects freshwater fishes in terms of osmoregulation. Water hardness also affects the regulation of blood calcium level, which also depends on diet. Freshwater fishes have adapted to thrive in an immense range of water hardness values, from the soft acid waters of the Amazon River, to the hard alkaline waters of the African rift lakes. Within any particular environment however, fish have tuned their physiological functions to cope efficiently with a fairly narrow range of water hardness levels and therefore osmotic pressure. Altering the hardness values outside this range or disrupting the major ion composition of water hardness will lead to extreme osmotic stress and other physiological malfunctions. As an example, if bicarbonate ions exceed normal levels then bicarbonate excretion by the gills fails, leading to an alkaline pH shift of the blood and symptoms of alkalosis. High bicarbonate levels also alter kidney functions, resulting in calciferous deposits in the kidney tubules.

Different fish species have a varying resistance to changes in water hardness, depending upon their ability to alter their osmoregulatory process to changes in osmotic demand. Most fish can be acclimated slowly to abnormal water hardness. In general, however, they will be under unnatural stress and will not achieve optimum performance in growth, breeding or disease resistance.

It is clear that it pays to provide your fish with water of the same hardness as they have evolved to deal with in their natural environment. [my emphasis]

If you aim to set up a community aquarium, be sure to select fishes and other creatures that share similar water chemistry requirements, most importantly the same range of hardness and pH levels--which are fairly closely linked anyway. Mixed community aquariums with softwater-loving tetras and rams living alongside hardwater species such as guppies and swordtails can only be a compromise situation. It would be storing up disease trouble for one or both groups of fish without deriving the best from either. [my emphasis]​