PlanetCatfish.com

I understand that this cory demands much more lower temperatures compared to his other relatives (around 20 degrees c), Why is it? I know that it's origin is the Rio De Janeiro river in Brasil, does the water temperature there is that low? isn't it a tropical region?

Is it possible to accustom the Barbatus for living in higher temperatures if I'm not interested in breeding? How much will it really effect him?

What is the right males/females rate for accommodation? shouldn't I keep them in pairs?

Thanks a lot...

The type location for S. barbatus is 22.5 degrees south, which is about level with Mexico City in the northern side of the equator. If you look at fish from that region, you'll find that they are also often listed an the "teens" temperatures.

The effect of higher temps depends very much on the actual species, but generally speaking: higher temperature leads to higher metabolic rate, which may make the fish unable to eat as quickly as the food is being consumed, leading to emaciation. Another effect is premature aging.

A side-effect of higher temperatures is lower dissolved oxygen levels, which is probably not a huge problem to Schleromystax spp., but should still be conidered when choosing fish and mixing fish from different temperature ranges...

As to mix of male and female, in nature there's probably an even mix of male and female (although there are plenty of examples where this isn't strictly true, and many examples of where environmental factors such as temperature or pH of the water will affect the mix of male and female fry in fish). The recommendation for breeding these fish is to keep two males for each female, simply because the males aren't very "efficient" at fertilizing the eggs. This is perhaps less important in nature where the fish live in fairly big groups, and there's probably always several males available for the fertilizing, since not all females are going to be able to spawn at any given time...

--
Mats

Refael Hdr.

S. barbatus inhabit the clear water streams of the mountainous region of the state of Rio de Janeiro, although now because of pollution they are restricted to the headwaters. The temperatures obviously vary over the course of a year, but generally the ideal temperature range for this species would be between 16º C and 22º C (61º F and 72º F). They will tolerate higher temperatures and many people will argue that "their barbatus are perfectly happy at 26º C (78º F)", but the truth is over a long period of time they will suffer and slowly fade. Given the right conditions they should live for ten or twelve years, maybe even longer. If you just want to keep some in a community tank there are plenty of species of fish available that would be very comfortable at the lower temperatures.

MatsP

The recommendation for breeding these fish is to keep two males for each female, simply because the males aren't very "efficient" at fertilizing the eggs.

Sorry Mats, this is not strictly true. The rule of thumb for many Corydoradinae species is as you say two males per female, but not for the reason you give as being inefficient at fertilising the eggs, I would be interested to know where this information came from.

The need for more males is basically to drive or work the female up into breeding mode and quite often a single male will give up before the female is sufficiently aroused to mate. However with S. barbatus and other Scleromystax species, it is better to breed or try to breed them in pairs, males particularly during the breeding season become territorial and will often have skirmishes with other males. If they are given enough room they will set up their own territory, defending it against other males, but will try and mate with any female that enters his patch.

Ian

Hi Ian,
What is the right male/female rate for regular housing in a community tank without breeding intentions, lets say 300 liter tank?

And thanks again...

Coryman wrote:... but generally the ideal temperature range for this species would be between 16º C and 22º C (61º F and 72º F).

Do you think it's fair to widen the range listed in the Cat-eLog from 16-19 to 16-22?

MatsP

The recommendation for breeding these fish is to keep two males for each female, simply because the males aren't very "efficient" at fertilizing the eggs.

Sorry Mats, this is not strictly true. The rule of thumb for many Corydoradinae species is as you say two males per female, but not for the reason you give as being inefficient at fertilising the eggs, I would be interested to know where this information came from.

I have no idea where that information came from (I'm sure I read it somewhere, but I'm not always good at remembering where I read things - I read a lot of different sources...) Thanks for the correction, however. I will remember that...

--
Mats

Actually MatsP, 16 - 19 is good and I would leave as it is, a couple of degrees warmer now and again would be fine and would emulate nature.

Refael Hdr, I would still recommend just pairs when housing S. barbatus.

Ian

To add my two-penn'orth worth on barbatus maintainance, I agree with the lower end temperature recommendation and would add that additional flow from a power head (although there's another heat source) or strong aeration seems to satisfy them. When breeding, the females will actively seek a strongly aerated site, and when hatching, I have had most success when maintaining aeration across the eggs.

With respect housing densities, I am not convinced that keeping a pair is the absolute rule. In a species only tank, my fish seem happier in a large group, with up to 20 individuals. This appears to mitigate male aggression and encourages spawning behaviour. Indeed, on removing half of the group all spawning stopped and the remaining fish reduced their normal foraging and active behaviour. Having said all that, I have had a dominant male kill another in a group size of only 5 individuals. The larger number of males has improved hatching success, I imagine through improved fertility of eggs.

In short, I think this beautiful species deserves it's own tank with optimum conditions designed for it, rather than compromising for the sake of other inhabitants.

Cheers,
Mark.

How do you all manage to keep the temperature that low in the summer?

Good question.

This summer my barbatus tank (bottom shelf of fish house) temp rose to 78F for about a week. Blowing a fan across the top kept it from rising higher. The fish were not unduly stressed, but I increased aeration and reduced feeding. My young barbatus at a higher level in the fish house, survived temperatures up to 84F for a few days, before I applied the same fan treatment to their raisng tank.

As has been mentioned, they will survive but not necessarily thrive in 'normal' tropical fish temperatures. They are really a coldwater fish. I would say that if you can't keep the temperature down for the majority of the time it may be best to chose a more suitable species.

I don't really want to push the high temperature experiment to test their ultimate tolerances!

Mark.

An optimal temperature of 16-19 celsius would put S. barbatus on par with North Atlantic Salmon or Brook Trout wrt temperature preference, and far below fish like e.g. pumpkinseed, goldfish, or yellow perch.
(source: "Temperaturpräferenzen und -limiten
von Fischarten Schweizerischer Fliessgewässer"
Stefan Küttel, Armin Peter und Alfred Wüest, 2002)

I've never kept S. barbatus, nor visited its area of origin, but to me 16-19 seems extremely conservative for a fish from the tropics.

The type location for S. barbatus at 22.5º south, is actually bordering on the edge of the tropic of Capricorn and could therefore be considered as a temperate species rather than a truly tropical one.

Ian