Some are, of course, but most of those common in the hobby not so much. Not that they need still water, some current is fine ime, but I don't overdo it.
Are geo fast water fish? Some, not all...
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I was shocked to see how much current Geos are found in when I watched some of the Oliver Lucanus below water videos
That was a god read thanks for posting.
I find hobbyists both under, and overestimate the flow in tanks. When fish are from quiet waters we don't have enough water movement in the tank. Adversely, when fish are described as rheophilic, we do not put enough current in the tank.
This, coupled with the layout of our tanks not giving all inhabitants a subjectively, "calmer" spot leads to issues in the tank. Many people would be surprised by the volume of water movement in these habitats as you mentioned. Even in the small streams during rainy season.
Having kept a number of rheophilic species for quite a few years I have learned to appreciate the subtlety of the flow in tanks. Studying the fish body shape and swimming behavior can give clues to whether more or less current is preferred, as well as, whether there is a need for more structure to be added.
I have also noticed people unintendedly confuse current with filter output flow. The filter out flows and circulation pumps can cause erratic, washing machine-like, flow patterns in the tank, whereas a current is a steady stream of water in an anticipated direction. This is my own opinion of course. But a planned unidirectional current is preferred by fish, and me, in my setups and experience. With planned current I can increase flow rate and/or volume with the fish still acting and swimming naturally.
A 75gal with over 20,000L unidirectional flow. The fish had structures to settle behind and between if they got tired. never saw that unless they were hiding from intraspecific aggression. This was specifically designed as a native (here) stream biotope.
The same 75 gal setup as a South American rapids tank with the flow direction slightly altered but still keeping the circular motion. Without this flow, I think some of these fish would have done more damage to each other. Tank on the bottom of the rack.
The very same tank with a community of fish, same flowrate and direction but more structure to give resting place. When lights were on, most fish hung out in the current.
A 55gal setup with a circular current with a flowrate of 7,500L/hour. The wall of plants acted as a buffer and refuge. Danios, rainbows, loaches and some others thrived in this tank.
I find the kind of water movement found for most slow water Geos ( compared to those that might be considered rheophilllic species) is about twice or 3 times the current found in most average aquariums.
Its all about perception. And habitat preference with the rive it self.
When I collect in an area, and have a hard time standing in the rush of water, in even slow water areas, the reality becomes quite apparent.
Some of the species I collect in Panama, that are very similar to semi-rheophillic Geophagines is deceptive looking from above the surface, and I have not always fully appreciated the strength, until once emersed in the river itself.
Beyond the water movement from my 1500 gph sump pump, to keep some of these species heathy, I have added two extra wave makers to mimic more closely the type flow rates the speciesare subjected to in nature.
The river iMargaritas n the video below, seems rather calm from above the surface, but once in it(and it is where we found a majority of Darienheros pictured above) its strength of flow was quite impressive..
Its all about perception. And habitat preference with the rive it self.
When I collect in an area, and have a hard time standing in the rush of water, in even slow water areas, the reality becomes quite apparent.
Some of the species I collect in Panama, that are very similar to semi-rheophillic Geophagines is deceptive looking from above the surface, and I have not always fully appreciated the strength, until once emersed in the river itself.
Beyond the water movement from my 1500 gph sump pump, to keep some of these species heathy, I have added two extra wave makers to mimic more closely the type flow rates the speciesare subjected to in nature.
The river iMargaritas n the video below, seems rather calm from above the surface, but once in it(and it is where we found a majority of Darienheros pictured above) its strength of flow was quite impressive..
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In practice, having kept them for years, the non-rheophile geos don't need high current, what they need (besides clean water) is enough dissolved oxygen-- give them that and they're just fine in a relatively quiet tank. On the flip side, also from experience and contrary to what some believe about slower water fish (Heros, Pterophyllum, etc.) they're just fine with some current. The natural habitat of these fish is variable, quite apparent if you watch enough wild video. The Rio Negro reportedly has a flow just over one mile per hour (though I expect that varies along its length) and some areas of flooded forest and meadow have very little flow. There's a video I've posted several times of Geophagus altifrons along a beach with very quiet water. On the other hand, yes, you also see the same fish in higher flow than most tanks.
The bottom line is a lot of these fish live in variable habitat and, excepting some of the specialist species, we shouldn't over-stereotype them. For example, in some places, quiet water fish spend at least some of their time in conditions atypical to what we think.
The bottom line is a lot of these fish live in variable habitat and, excepting some of the specialist species, we shouldn't over-stereotype them. For example, in some places, quiet water fish spend at least some of their time in conditions atypical to what we think.
Great topic. Just wanted to add, even in water with swift current, most species will seek out a break in the current, behind rocks, fallen trees, etc, to feed, rest, etc.
Of course most fish need areas to sequester,
but flow is not just about speed of current.
Many rheophillic species require a generally higher dissolved oxyen content, than slack water species, and are subject to hypoxia induced stress diseases, if not provided.
This is why we often see those "mystery" ailments such as HITH cropping up in the disease section.
Keeping high dissolved O2 users such as Geophagines, Tomocichla, and Darienheros , or even swift stream dweller like Denison Barbs, is not like keeping a Betta, or severums, anglefish, or snaleheads.
Fish like severums can tolerate DO valvues of 5 ppm, and do well, where as most most Geos, do best when DO is double that.
Even some Chaetostoma plecos that I catch are only "willingly" found in highly oxygenated riffles and rapids, expecialluy as they age.
And in my tanks, gavitate to those highly aerated areas.
Although there are generic standards most fish will tolerate in the hobby, and live somewhat adeequately
There are things that transend mere surface scrapes to be successful, especially when digging deeper into the abyss..
but flow is not just about speed of current.
Many rheophillic species require a generally higher dissolved oxyen content, than slack water species, and are subject to hypoxia induced stress diseases, if not provided.
This is why we often see those "mystery" ailments such as HITH cropping up in the disease section.
Keeping high dissolved O2 users such as Geophagines, Tomocichla, and Darienheros , or even swift stream dweller like Denison Barbs, is not like keeping a Betta, or severums, anglefish, or snaleheads.
Fish like severums can tolerate DO valvues of 5 ppm, and do well, where as most most Geos, do best when DO is double that.
Even some Chaetostoma plecos that I catch are only "willingly" found in highly oxygenated riffles and rapids, expecialluy as they age.
And in my tanks, gavitate to those highly aerated areas.
Although there are generic standards most fish will tolerate in the hobby, and live somewhat adeequately
There are things that transend mere surface scrapes to be successful, especially when digging deeper into the abyss..
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