Water movement… over looked I think in a lot of fish…

My tanks would typically be thought of as over filtered, and because of this most are “river” type tanks… I’m going to use South American tetras as an example… lots of these were for sale when I had tanks 25 years ago, and often sold to aquarists with 10 gallon tanks, and the little bubbling plastic cartridge box filters, that were common back then, and they made for peaceful, relaxing, viewing, but we just didn’t think about the Amazon river system ( no, not the mail order company ), and how much water moved in the areas, that a lot of these fish habitat… thanks to the video posted in my Gold Nugget Pleco thread, I was reminded, about their natural lifestyles… my South American tank, has 2- Aquaclear 70’s , and 2 power heads on 2 under gravel filter lift tubes, and a 20 inch bubble waterfall, in a 65 gallon tank… it doesn’t look like a torrent, with all the hard scape, and terrestrial plant roots through out the tank.. but the fact that several of the tetras regularly try spawning, indicates they are happy… most were not lake fish, it’s lucky they lived as long as they did back then… I personally like to research where the fish came from, and not necessarily duplicate the surroundings, but do my best to duplicate the conditions…

I like to try to make a few different "zones" for my fish. I like a lot of flow too, but I try for calm areas for fish to rest in if they want. In my "river-ish" 55g tank I have 2 AC 70s & a Maxijet 1200 powerhead along the back. I have sewellia lineolata that breed, a couple stiphodon gobies & 12 "blue line rasboras" (sarawakensis). I have rocks along the middle bottom & a lot of plants too.

Fish, IMO adapt to different conditions that suit them if they have that choice. It sounds like your tank offers that I'm not a bubble wall fan

I haven't used UGF for many years, but my husband still thinks they're the way to go. Almost 40 years ago, all our tanks had airstone driven UGF. Not while I'm "in charge" of our tanks these days, lol. But I use at least 2 filters on all tanks 20g & up.

We need to consider seasonal "native" conditions too. Monsoon flooding rains or a long dry season? Our fish are more adaptable than we might think.

I was sorry we never tried reverse flow UGF. Back in the day we hadn't heard of that. But rather than trying to clean under the UGF plate (a major PITA), it pushes the crap up through the substrate into the water column to get sucked up by HOBs. But UGF filters are not so plant happy. The roots get tangled in the plates with lots of damage when moving them...& making UGF plates even harder clean under.

I'll have to check out your G. nugget thread. They are I fish I've wanted but not that I ever had a tank for. Can you please link me, I'm still learning my way around here, thanks.

My 55gs are run on canisters, but on top of that I use 528gph wavemakers for flow. Sometimes I angle it lower, sometimes up top for a lot of surface agitation, especially in summer here because it has gotten really bad for heat waves a few times.




Then my goldfish tank runs on an even stronger wavemaker, at 1300gph


It's angled upwards, so the surface takes most of it, but the fish are also big, so the flow is a joke to them.


Only my small tanks lack significant flow, because the fish in them don't like flow (betta, for example)

I enjoy watching underwater videos in nature. You see how much flow even the small blackwater streams have, it's nuts. The tetras there truck through it like nothing. What we consider "high flow" in aquariums is often nothing compared to what many use in the wild.

Great to create spaces where it's slower or faster for fish needs and for them to choose where they want to be.

@fishorama … this is the thread that has the video I was referring to above, thanks to member @TwoTankAmin … for posting it…

When I had tanks 25 years ago, everything was under gravel, back before the www. Advancements were slow… I did have a tank with reverse flow for a while, but it made the big pleco poops float around the tank, in my one tank I tried… when I restarted my old tanks, after sitting for 25 years, I pulled the under gravel filter plates out of all but 2 of my tanks… I will say, that while I use primarily other filtration, the 2 tanks that also have under gravel filters seem more stable… the tank I mentioned above, is probably my “best” tank, but it also has a literal jungle of terrestrial plants growing out of it as well, and was a tank of the month winner…

I have become a big fan of the bubble waterfalls… they don’t have to be a focus, on two of my tanks I have them on the sides, and one of those, has a large piece of driftwood, and a tangle of Java ferns in front of it, and you can’t really tell it’s there, when looking at the tank, but it does greatly affect increasing the surface flow, and coupled with a Tidal 75 hob, really makes that a “river” tank…

On 2 of my tanks, I have 20 inch bubble waterfalls in the center of the back… these of course are much more noticeable… one is my Hillstream tank, and those fish are often viewed “surfing” in the current, on the back wall

There's a simple experiment any aquarist should try, in summer. Look around your region. Choose a lake, a stream, a brook and a large river. Go to them, take your shoes off and stand in them. The average still looking lake has a lot of swish around the edges, and away from the shore will drag 220 lbs/100kg of me in a kayak around even if I don't paddle. It looks still, but it moves far more than the average aquarium.

The river, stream and brook also push and pull at your feet. It feels good.

Then go to a stagnant pond, with greenwater, frogs and an unpleasing smell. Bazinga, you have found a natural fishtank. Go tell father fish!

That experiment will tell you about water movement where our fish live.

I've fished for aquarium species in Central Africa, and North and central America. I didn't catch anything in stagnant ponds, although maybe I could have caught malaria if I'd hung around too long. I became used to water running at a steady fast clip almost everywhere. I caught African Anabantoids and killies in water that would have knocked me over if I hadn't placed every footstep carefully. I found fish that liked quiet water, but it was generally well oxygenated and made still by overhanging plants, and roots in the water. The still water zones are easy to make in aquariums, but the world around them is in constant movement.

I see no logical reason why tanks shouldn't be in movement, unless we have intentionally handicapped fish like fancy Bettas. You have to do it thoughtfully, as glass walls don't exist in nature, and create turbulence and swirling at too high rates of flow. But with a little common sense, and the realization that water moves outside, we can do better inside.

Thanks for the link Magnum Man, I'll check it out after dinner or tomorrow.

GaryE, I like your idea but there's almost always nooks under rocks etc. They do allow some more calm areas for fish that like it a slower pace or a rest, as you said & then there's the seasonal changes too.

Back when we kept bettas, they sometimes liked to play in filter flow. Sort of like exercise or boredom relief? But there are many more varieties with huge fins now.

Some plants grow better with higher flow too. Bolbitus fern comes to mind. Flow or oxygenation? Others not so much. I forget which crypt (mohlmanii? or similar) melted any time I trimmed stem plants...or changed lots of water. Never again? Well, I might try it again...without expectations.

I used to believe that high flow was needed for the plecos with which I worked. After all, the Big Bend of the Xingu is filled with rapids. And plecos which live in rivers have certainly evolved to survive in high flow environments. So it is logical to assume that they need them. But the water in the Big Bend gets quite warm, and of course the fish there have evolved to thrive in water than can get above 90F at times during the year,

Science also tells us that the warmer water gets, the less oxygen it holds. The rapids in the Big Bend keep that water well oxygenated. Without those rapids, the fish would likely have died off. In fact, zebra plecos are only found in the Big Bend of the Xingu. There is a reason for this. At either end of the Bend are areas of deeper and slower flowing water. Their lack of rapids means there is less dissolved oxygen in the water. And this has as acted as a barrier which prevented the zebras from migrating beyond the Bend. There is not enough oxygen for them to survive the crossing. Also, the floor of the Big Bend is a unique environment in terms of the topography. It is not found in many places at all.

This all was really brought home to me when one of the people who bought zebras from me and who was one of the top of the board breeders on the Planet Catfish. He was breeding species one after the other. He also was a speaker at one of my club's monthly meetings. I had also been to his home and seen his setups. What impressed me greatly was his filtration. He worked with a lot of smaller pleco species breeding them in smaller tanks. His filtration was not at all what I expected. He ran air powered Poret cubefilters. He would have several of them in a tank. There were no canisters, no power filters and no power heads or wave makers. So there was not much in the way of strong current.

What he had was great filtration and lots of aeration. This is essential in tanks with fairly warm water. All of the cubefilters bubbled away breaking the surface and providing the needed level of dissolved oxygen. What was lacking was the strong flow typical of many pleco habitats. And this finally made a bulb above my head light up. My plecos did not need a strong current to thrive, what they needed was good oxygenation and some current.

Over time my pleco tanks evolved to where great filtration and excellent oxygenation were provided but all my powerheads and many of my power filters were replaced by Mattenfilters and Cubefilters running on air power. At the same time I finally understood how important the right diet was.

The plecos I kept were small and they spawn in caves. In the wild they spawn in places where the current is greatly reduced. The most important thing they do to keep their species going is reproduction. For this they worked to get out of the current, not into it. The fish evolved in rivers and this meant they needed a way to avoid being swept away by it. And this led me to question the idea that they needed high current to survive. They developed a sucker mouth to hold on because they lived in current. It takes a lot of effort to hold on all the time.

So I began to change how I set up my tanks. I paid the most attention to oxygenation and having loew TDS water and I became much less concerned with flow rates. As long as I had some flow and good circulation, my plecos spawned, and spawned and spawned.

So I am not sure how much flow some of the fish which come from higher flow areas really need when they are in a tank. I am not saying that none of them do. Most fish which live above the bottom in higher flow environments tend to have torpedo shaped bodies. Fish like discus and angels and other fish with larger thinner bodies do not usually live in higher flow. To be able to thrive in really higher flow usually takes a larger size fish. Where they live, small fish would be blown away by the current.

However, my first adult discus went into a 75 gal. tank with an Eheim Pro II 2026 canister (250 gpH) filter and an AquaClear 300 aka 70. They seemed occasionally to enjoy swimming straight up to the canister spraybar output and then turning sideways letting the output sail them across the tank.

Also, to be able to thrive in really higher flow usually takes a larger size fish. Where they live small fish would be blown away by the current.

And a curveball from the killie world. That's the slowest water hobby out there, yet other than one Epiplatys singa with a fungus infection, we never caught a killie in slow water.
The almost mythical Aphyosemion joergenscheeli was in quick moving very shallow water over a sand bottom, where it liked the shelter of rocks and fallen wood. A friend caught a female above a small waterfall (maybe a metre's drop), but I caught males in the highly oxygenated water in the quick flowing, beautiful stream. We also caught Aphyosemion citrineipinnis in the same net sweeps.
Both are fish breeders say must be kept around 19c. They were in 22c water.
Is the oxygen the key? I think so.
Maybe the tactic of using cooler water to compensate for the difficulty of maintaining higher oxygen levels in small tanks has given us a skewed view of how some fish live.
I now have some Diapteron georgiae, a well known cool water killie. I got close to its habitats, but not close enough. Reading and photos show quick little brooks, riffles. I saw a lot of habitats like that out of their range, and caught Epiplatys huberi in one of them.
My Aphyosemion zygaima, which like around 20c for maximum egg production (knowledge gleaned from my breeding them for 33 years now) come from a babbling brook in a ravine, spring fed and running downhill.
I know from experience that some rapids species can become aggressive without the exercise of current running. I also see adaptations, like reduced swim bladders, that allow my rapids Cichlids to thrive along the bottom, where rocks create calmer zones. Even a fish that stays between rocks, like an Ancistrus or a Steatocranus Cichlid is surrounded by oxygenated water.

I was skeptical of @Magnum Man 's use of airstones, but I'm starting to see a great idea there. It's a reason why talking with people on forums is never wasted time (unless fishkeeping is....). I stopped using airstones because they clogged, and I thought they wasted energy. Now, I'm going to try some with my weird killies.

We also could be thinking of different things when we say "water flow"" and "currents".

Along this same train of thought, I noticed how warm my Hillstream tank has gotten this summer… heater is set at 70 degrees, but the room temperature is 75 degrees, and that tank, over the course of summer, has risen to room temperature… we recently raised the air conditioning temperature, to try to reduce the electric bill, a little… so, during the summer, I need to make sure I’m oxygenating as best I can… there is definitely increased surface agitation, coming from the increased flow on the modified Tidal filters… hopefully that equals the oxygenation from that infernal sucking sound that was the reason for the modification… I do think the bubble waterfalls are an integral part, as an oxygenator, and a habitat replicator, as the Hillstream’s are almost always in the areas of high water movement…

And as a side note, the tetras have bubble waterfalls in their tanks, but neither the South American, or African, spend any time directly in the waterfalls, but both spend a good portion of their time in the resulting currents, and neither look like they are hunting for, or spending much time in the corners or areas of lower current…

I think of oxygenation as surface movement, helping to dissolve atmospheric oxygen; different from flow or current. In my "river-ish" 55g tank I use 2 Aqua Clear 70s & a Maxijet 1200 powerhead along the back & lower than the filter intakes. The filters (when clean, ahem ) create a more circular flow that, even with duckweed & long vallisneria really moves the surface at the return area. I sometimes allow the water level to drop to create more splash & bubbles especially in summer (AC at 76F). The powerhead doesn't add much surface movement although it's aimed slightly upward. It's more for fish that like flow rather than a source of oxygenation.

I have also used the "jet" return with canister filters (Rena 3s) rather than the more gentle spray bar attachment. I don't heat the tank. Between the filters, PH & lights it stays in the low 70Fs even in winter when we heat to 69F during the day, less at night; warmer in summer. I only heat 1 tank but, man, it loses as much water to evaporation as my tanks 3 to 5 times as large with usually open lids. A different issue, sorry, slightly off topic. (I tend to babble as people who know me understand. Ask 2tank & Cass, lol)

I just don't like the tiny bubbles from air stones or especially bubble walls. It more an aesthetic issue for me...& as GaryE said, the clogging, always a problem when we used UGF or the old corner box filters. Not enough surface agitation to make much difference.

Plugging of air stones, I have had that problem in the past, but not currently… my thoughts as possibly why…

Reason 1… Size of the actual air stone… smaller seem to have plugged fast, they used to sell these little ones, that were slightly bigger than the air lines, to insert into the lift tubes from the under gravel filters… those seemed to plug right quick… when I restarted my tanks about 2 years ago, all my lift tubes had 4 inch triangle air stones in them… I found these did not clog right away, they blocked more of the lift tube, but I suspected an increase in velocity, probably made them perform equally… right now, I have one under gravel filter, that is still using those 4 inch stones from 25 years ago, the other has a power head on each lift tube… all other air stones were purchased, when I restarted my tanks, roughly a year and a half ago…and are 10 inch stones, I chose that size, so they fit nicely on the short sides, on a typical bigger tank… the 20 inch bubble water falls, use 2 stones, end to end, and most of these have been running close to a year and a half, without noticeable plugging…

The Tilapia tanks outside ( farming ) are 6 inch stones, feeding 50 Tilapia 4-5 times a day, the water quality is challenging… I’m noticing a little plugging, on the 2nd year I’ve used them…

Reason 2… minerals in the water… we have “rock hard” water here, I always have… currently my aquariums are using RO water, so very low minerals…. The Tilapia tanks outside, are not using RO water, so maybe the reason I’m seeing some plugging, besides the farming is “dirtier”, is that those tanks are using hard water???

Hmm, that's seems interesting. In our first 2 fish keeping households we had hard water, lots of minerals & more air stones. The last 2 places we've lived have/had softer & lower mineral content. Only 1 tank with air stones. I'm sure that would make a difference in air stones clogging & other issues. It's hard to adjust our tanks to different water & fish needs, there isn't 1 way to care for our tanks. It's a balancing act with a learning curve every time.

It sounds like you've kept fish in similar water all along?

The above is why I have switched a number of my tanks to using 100% air powered Poret foam filters- either Matenfilters or all cubefilters. This means I get double duty from them all. the water gets filters and the surface gets roiled 24.7.

When at the peak of breeding Hypancistrus I switched over the 6 grow tanks to 100% air powered filtration. One major reason beuond the above, thay led me to this change was something I learned from Sr. Stephan Tanner of Swiss Tropicals. Most of what we think of a needing mechanical filtraion is actually biological. A great explanation of this is on Dr. Tanner's site in this article https://www.swisstropicals.com/library/aquarium-biofiltration/

Some of te clearest water I have is in tanks filtered solely by Poret foam. No filter floss nor any other mechanicl media is used. I can put a page with 12 pt text placed on the back glass of a 12 inch wide tank and read it though both the front and back glass and the water between them.