The varied current of natural habitat

[neutrino]

From still to fast water, apart from strictly fast water, rheophilic species, many South American cichlids happily adapt to variations of current in the wild, and occasionally contradict our stereotypes for fast or slow water species.

Pantanal--

Heros notatus, Hypselecara, etc--

Sheltered areas, dipping in and out of the current--

Flooded forest--

Angelfish in strong current--

 

[jjohnwm]

I think there is far too much emphasis placed on high current flow rates by many aquarists, for many species of fish. In the Canadian waters where the bulk of my observations take place, species that are commonly thought of as preferring or requiring high flow rates still spend a great deal of time simply resting in the low-current or "slack" water behind boulders, logjams, etc. and only dart out into the current to snag a prey item or other food morsel that comes by. This type of behaviour is well-known to fishermen pursuing trout and other species who live in this type of water. These fish certainly require high oxygen levels, but they don't spend all or even much of their time wasting energy fighting the high current. Occasionally, perhaps immediately following a hatch of some aquatic insect species, the fish may exhibit a feeding frenzy...a "bite"...that is very reminiscent of the behaviour of aquarium fish when the owner approaches with a can of food in hand. During these feeding sessions they may remain in the main current for many minutes, gorging on a temporary bonanza of food...but those periods of frenetic activity, both in the aquarium and also in the wild, are relatively brief.

I read a post recently here on MFK in which the poster expressed some level of surprise at the reaction of his fish to an increase in flow rate. A new/bigger/faster/more-powerful pump had been installed and dialed right up Heavy Rinse levels, and the fish did what most of them do in nature in such conditions; they huddled in the lee of rocks and decor, conserving energy. Imagine that! They didn't want to fight the current continuously...just as cheetahs don't spend all their time running at 60mph and whales don't dive to hundreds of feet while holding their breath all day long. These creatures have evolved abilities that they use to survive and find food and escape predation, and they use these abilities when they have to and as much as they have to but don't wear themselves out non-stop.

In this as in all things...more is not always better. In our tiny aquariums...and even the biggest of them are tiny in comparison with a natural environment...we can't hope to approximate the huge variations in current flow that are apparent in even small streams and creeks. We can't install boulders the size of refrigerators in most of our tanks; even the largest aquarium rock won't break an extreme current flow enough to create a slack water area behind it, so it's probably a good thing that we can't recreate the torrent of a trout stream in the tank...although many people seem to want to do just that.

The most immediately apparent exception to the above would likely be fish such as plecos, hillstream loaches and others who have evolved mechanisms that allow them to cling to rocks and other surfaces in even the most extreme currents. They aren't burning calories fighting the current; they just hang on and maintain position without much expenditure of energy. They are the exception that proves the rule, having found a "work-around" that gives them a niche all their own.

I'm not suggesting that a completely stagnant tank is ideal, although for some species it isn't far off. You can definitely have a tank with insufficient water flow for some species...but it's also possible to go too far in the other direction and provide too much. Common sense and a reasonable interpretation of the way most fish live in high-current areas dictates a middle of the road approach, a compromise. In the real world, "compromise" isn't a dirty word; it's the pragmatic ideal.

 

[RD.]

In the wild, I have yet to observe a creature, fish or otherwise, waste any form of energy resource.
In nature the current works for the fish, not the other way around.

 

[duanes]

The oxygen content in even slow flow waters in Canada, or the northern US, in places like the cool (50"F) waters of Lake Michigan, is usually saturated at over 10 ppm DO.
In the tropics in waters that are at, or close to 80"F where I collect, and be only half that amount of DO.


And seeing that we as aquarists have closed systems, without access to wild type parasites (except when fish aren't QTed),
why are there are so many posts in the disease section? Is it Satan?
My take is that aquarists don't really provide the right, or real conditions fish have eveloved to need,
Whether that be lack or flow, or nutrient over load etc etc, yaa yada.
Below is a typical flow of rivers where I collect, is this a typical aquarist tank flow rate?

soon after the video was taken, this species was caught in its waters

among others a number of gobies, plecos, and loads of tetras were netted., in that same flow
Does this mean all these fish require the water flow of the video above, maybe not severums or angelfish, but geophagine, or Tomocicla,
I believe too many aquarists are half stepping compared to natural flow reality.
And add to that, the competition that high acceptable nitrate concentrations do to abilty to take in dissolved oxygen, its no wonder the disease section is filled with "mysterious" ailments.

 

[jjohnwm]

Mysterious ailments seem less mysterious when you consider how few aquarists practice quarantine; even those that pay lip service to the idea often seem to think that staring at the fish in a QT tank for a week or two will reveal all its problems. It surely won't, and most of the fish we buy have gone from one tank to another to another before we get them home. Each of those tanks is often exposed to who-knows-how-many different fish from all the corners of the globe...each of whom has also gone through a string of assorted tanks with assorted tankmates. Add to that the high levels of nitrate and other nutrients that accumulate in most aquariums, and it's honestly surprising how few of our fish actually come down sick. It's a testament to how tough and resilient most of them generally are.

Just because a river has 15 bazillion gallons of water flowing through it every second does not mean that every cubic inch of the water in a given section of the river is experiencing that kind of torrential flow. There are the open areas in the main flow that do, but there are also many backwaters and pools and eddies and areas of slack water on the downstream side of rocks, etc. And that's where most of the fish spend most of their time. Of course some species are more willing to put in the work to spend more time in the main current than some others, but I doubt that there are any that will spend all their time there.

If a successful experienced angler approaches a section of water with which he is unfamiliar he will not just cast his line in willy-nilly anywhere, and almost never will choose a big open area without any cover or complex current patterns. He will seek out those backwater, slower-moving areas because he knows from experience that most of the fish will spend most of their time there. Unless there is an aquatic insect hatch underway, that angler knows that he must present his fly very close to where the fish are holding. The less aggressively they are feeding at any given time, the more critical the accuracy of the cast will be. They won't dart even 5 or 10 feet to strike a fly most of the time; it requires a bait that is right in their faces to tempt them. They must overcome their reluctance to expose themselves to heavy current and predators and burn all that energy to swim in the strongest currents.

It isn't enough to know there are lots of fish in that stretch of the river; if you don't or can't read the water and deduce exactly where they are...where they spend most of their time...i.e. where they live...you ain't gonna catch many or maybe even any. They don't just live in the river; they live in specific comfortable spots in the river and that's a whole different thing.

Oxygen is obviously a concern, and more so in the tropics than in my locale. But the oxygen content of the gentler water in their holding spots is just as high as the rest of the river. The violence of the water allows for a high dissolved oxygen content, and it is everywhere, not just in the main flow.

 

[duanes]

I agree that many species rest under logs etc out of the current, but this does not mean certain species need for DO is any less, especially from lack surface agitation and air exchange at the air/water interface, the way it happens in nature
And this is what is often missed by many inexperienced hobbyists.
Andis who I am aiming at with my rants, not old dogs, who are set in their ways.
Most experienced aquaists have realized somewhere along the way what is needed in their tanks, thru observation or fish death.

It's some of the new blood who are often baboozled by adages like "nitrate are fine at 50ppm" when science tell us they are toxic, or geos in nearly stagnant tankks won't get HITH, or oscars can live fine in 50 gal tanks with only a 25% water change once per week in pH 8, when we all know some might, or sure, keep your beanii and trimac in the same tank together (they wont fight to the death) but with many of the this aquarists are often told, the majority of fish will kick the bucket in 6 months or a a year withthe goofy advise that is often given.
.
I don't sugar coat, or tell aquarists what they want to hear, just because some old dog like me has bypassed reality by for-going water changes or water movement that could be the difference between a living tank or a dead one.

The natural world gives us clues, and even though tanks are far from natural, some eal world insight may come in handy.

 

[duanes]

An example, there was a question in the disease section not long ago about why certain Rio Negro Pike cichlds, and Uaru ferandezyepezi kept getting sick and croaking.
There were many theories in the answer section, and med suggestions

But what no one asked....was a couple pertinent factoids.
These pPikes and Uaru are from the Rio Negro,usually wild caught, coming from pH 4 water, tannin stained brown water, almost 0 hardness, and in flow average rates that come close to 28,000 M per sec. (oxygen rich, and constantly changing water)
The aquarist with the sick cichlids, had a tap water pH of over 7.5, moderatly hard, and a (what I consider a wimpy ass) canister for filtration.

To me the answer was obvious, and to me, getting that species with the tap water parameters available was an exercise in futility.
I would have advised against it, and suggested getting normal Uaru (tank raised) and although from the main Amazon, able to tolerate moderate changes, although I would have still advised a serious filter upgrade (knowing me, a heavilly planted sump, with no less tha 1500 gph pump rate, and lots of turbulence)

 

[neutrino]

An example, there was a question in the disease section not long ago about why certain Rio Negro Pike cichlds, and Uaru ferandezyepezi kept getting sick and croaking.
There were many theories in the answer section, and med suggestions

But what no one asked....was a couple pertinent factoids.

I see this as a common failing, sick fish threads that quickly fill up with contradictory diagnoses and recommendations for treatment, often when the original post didn't mention tank size, water conditions, what else is in the tank, etc., sometimes without any photos-- and no one asks questions. It keeps me out of a lot of sick fish threads-- unless I clearly see something others missed. Not much point adding one more contradictory post doomed to be lost in the noise,. At age 70 I have better things to do.

Moving on to another point. It's clear from the videos I posted (I could have posted many more) that current varies widely in SA habitat, which can be anything from tumbling rapids to strong river flow to flooded forest or meadows with little detectable current, as well as lakes and ponds. How is there enough oxygen with low flow and in some places virtually no surface agitation? Or, for that matter, how can fish anywhere survive in natural ponds with no real current and no surface agitation (unless the wind picks up and ripples the surface)? A lot of the answer is surface area, water volume and/or plants vs fish load. It's why you could have the early, Victorian glass aquariums or the marble ponds and such of ancient times, all without pumps, filters, or current, they had to balance fish load with volume, surface area and plants. It's interesting to read what the very early Victorian aquarists had to do to figure things out.

Some do pretty much the same thing today. With a load of plants you can keep a few small fish in a tank without mechanical assistance. It's not what most of us want to do, but that doesn't make it bad practice. The point is (excepting specialized fish like anabantoids on one end or rheophiles on the other) there's no one-size-fits-all formula for current, as long as there's sufficient dissolved oxygen-- and there's more than one way to get there, which can include light stock levels, what some might consider to be low flow, and some surface agitation. In my experience, fish that spend at least part of their year in similar wild conditions don't mind a bit-- and I normally go years between sick fish, sometimes as many as ten years or longer.

SO... am I 'set in my ways?' Or, just maybe, after many years doing this I know what I'm doing.

 

[jjohnwm]

Nothin' wrong with being set in your ways...when your ways are working.

It's always better to stay healthy...rather than having a vast arsenal of medicines and methods to cure problems and get back to being healthy after becoming sick.