Katria katria in oxygenated current

Discussion about cichlids from Madagascar and India
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Janne Aho
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Katria katria in oxygenated current

Post by Janne Aho » Mon Oct 26, 2009 10:28 am

Hi everyone!

After wondering about how Katria katria from Nosivolo River manage with plants (Topic: Katria katria and plants), I did buy four katria, 2 males (now 4 and 4,5 inch) and 2 females (3 and 3,5 inch) into my 95 gallon East Madagascan biotope tank with 13 Bedotia geayi from the Mananjary River near Nosivolo. My katrias were sent from France to Finland to the only aquarium store specializing in the fish species from Africa. At the beginning I had three Aponogeton ulvaceus plants in my tank (also from eastern Madagascar). Katrias did not pay any attention to the plants but the fishes did not show any spawning behavior either (pre adults?) which might change katria’s behavior. Now the plants are in dormant stage and are resting at the balcony. I found scientific information about the Mangoro River (the biggest river in the eastern slopes in Madagascar) and its tributary the Nosivolo River and katria’s biotope. Also the Article ‘Oxylapia polli, the enigmatic cichlid of the Nosivolo River’ reveals something about the biotope structure in which katria lives. Like the main stream Mangoro the Nosivolo River is rocky with stretches of calm water, rock-fringed pools alternated with numerous rapids. No mentions about plants. So the Aponogetons will be history. I have now fairly strong currents to the both directions in my tank and katrias seem to enjoy that very much and bedotias naturally. In my tank there are also a lot of current sheltered rocks (the whole bottom is rocky) and a lot of driftwoods, also for the two females to escape males’ aggression. I have tried to imitate a streamy river bank with different water movements. The bigger male is sometimes dominating the tank but the aggression seems to be quite moderate so the other male and the two females have their own places in the tank. They stay almost all the day in their own sheltered places (hiding out the dominating male?) and the dominating male in the oxygenated main current most of the time, but every evening and night after the sunset (the lights) all the four katria gather very very close together in the oxygenated current for hours with no aggression at all. The night has a story of its own.

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Vincent Fu
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Re: Katria katria in oxygenated current

Post by Vincent Fu » Wed Oct 28, 2009 5:25 pm

Your research into the natural habit of Katria katria is impressive. Do you have any photos of your fish and tank? I did not keep precise records, but I believe that my first katria spawn occurred at sizes larger than yours. Best wishes.

Janne Aho
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Re: Katria katria in oxygenated current

Post by Janne Aho » Sat Nov 28, 2009 2:32 am

Hi Vincent!

And thank you for your polite comment. I hope I will learn a lot more with time. I will send photos about my tank and katrias before Christmas. Every morning at the sunrise I watch my katrias (also beautiful bedotias) and wonder what is katria's biotope like in the Nosivolo River.


Nuchal Man
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Re: Katria katria in oxygenated current

Post by Nuchal Man » Tue Dec 01, 2009 5:21 am

Wow, sounds like a cool tank.

I bred my Katria under far less natural standards. Mine bred at 3.5 inches for the males and 2.5-3 inches for females. Kept them in a 110 gallon tank with sponge filters. Temp was 84 °F and water changes were performed twice a week at 60-75% volume. The water added to the tank was a little cooler. 12 hour lighting. Tank mates were young Petrotilapia sp. "chitimba" which were used as target fish as the fish got relatively quarrelsome with each other, but this seemed to help and I think helped form a strong pair bond. The fish have bred in the same spot a few times which is a rock with a drain tile overhang.

This fish is in my top 3 favorites. Very neat fish to watch and I really enjoyed them.

Good luck,



Re: Katria katria in oxygenated current

Post by emartin » Tue Dec 01, 2009 3:15 pm

Based on the size of Katria katria I think it could handle currents but keep in mind that just because the river they are found in has rapids doesn't mean that they like them.

The biggest examples are Steatocranus for example. They do not go in the rapids but rather try to stay away from them in the calmer areas (where there's still some current but not as whirlpool-ish as the rapids). While I have never kept them I know people have experimented with powerheads and found that they just go underneath the powerhead that they do not seem to like currents.

Given the physical build of Katria katria it can probably handle it but it isn't streamlined for speed like Crenicichla (also can be found in rapids) for ease in swimming in rapids and fast current water.

My point is, I don't think adding extreme currents in the tank is a good idea. Adding lots of air stones for extra extra oxygenated water though does sound like a great idea since it sounds like that even if they are in the calmer areas of the rivers that the water would still be extremely saturated with oxygen.

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Re: Katria katria in oxygenated current

Post by sidguppy » Thu Dec 03, 2009 10:03 am

in my experience it goes with many rheophile fish; all about the oxygen

I've kept Retroculus in with my Madagascar fish for a while; they did just fine. ate well, colored up just fine.

now they have a tank for themselves at another hobbyists' place.

my secret: a trickle down filter between biofilter and tank......trickle filters make the oxygen levels go through the roof!
wich your fish like. a lot.

I've had succes with other fragile oxygen demanding fish in that tank as well; I've kept Bathybates fasciatus in there, up to 8" from a mere 3".
not with Mada fish of course but then the tank was Tanganyika. this too is a fish wich needs a truckload of oxygen or else it'll perish.

in the near future I'll be keeping Katria if all goes well :D
and I'll make very sure that regardless of current, the oxygen will be there!
"And he piled upon the whale's white hump the sum of all the rage and hate felt by his whole race. If his chest had been a cannon, he would have shot his heart upon it"
Jean-Luc Picard

Janne Aho
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Re: Katria katria in oxygenated current

Post by Janne Aho » Wed Dec 09, 2009 3:35 am

Hi emartin

A good point to discuss the biotope structures! Thanks emartin!


Interesting and challenging topic and how to imitate natural biotopes with currents (when there are currents) or without currents is fascinating. In the nature in the riverine biotopes the currents can be and they are much faster than we have in our aquariums. Even slow moving water flow in the nature can be a faster current for aquaristics. It would be great to get more knowledge about natural biotopes. Authentic videos are one and sometimes a good way to realize biotope structures, including river streams and currents.

To make sure I’m not misunderstood, I do not have extreme currents in my Madagascan tank. Extreme biotope currents are only for some rapid riverine biotopes, like in Lower Congo. The water is moving fast and violently also between the huge and angry rapids. They are not for Katria katria. Its biotope is different (the river is different) in the Nosivolo River; there are calmer sections alternating with small stretches of smaller rapids. What actually means a calm section? So many aquaristics I have been met usually think water flow is almost stopping in the so called calm sections between rapids but generally the water velocity after rapids and between rapids can be still quite fast. Only the side-pools off the mainstream are totally or much calmer. What actually is a strong or a slow current for a fish species?

I agree based on my experience and others and the scientific knowledge that a fish species which can handle strong currents does not mean it is anatomically or physiologically adapted itself to currents or even likes them. But there are a lot of exceptions. A fish species whose physical build is not streamlined can play long times with water currents in aquariums. They must have fun and they enjoy that. And there is always a reason (to explain it scientifically) for a fish doing so. I wrote that I have ‘strong’ currents, but I wanted to emphasize that they are ‘strong’ currents in a closed space, in an aquarium but they are not fast or strong currents in the nature. I use (at this moment!) one powerhead with oxygen diffuser (OD) (its power can be changed from slow to fast) on the left side and one Hydor Koralia circulation pump on the right side up (plus one internal filter with OD and one canister filter). This means a lot of saturated oxygen, like in the Nosivolo River. More accurately the oxygenated water is moving about at the same velocity (only some distance) AND slower as in the first order rainforest stream and only at certain and different levels in front and back in the tank (In the first order rainforest stream the current velocity seldom exceeds 0.5 m/sec ). There are long and calm sections in the tank (water is moving slowly) for four katrias and their habitats, naturally. So I can study the behaviour of Katria katria and its likings and preferences for water movements, also by closing the powerhead for hours or days and closing the powerhead only the surface water is flowing. Then my tank might resemble a deeper pool section between rapids (see the next paragraph). This means study possibilities and the possibilities to change and develop the biotope.

As I wrote all the four katrias gather close together every evening underneath and also on the upper side the oxygenated powerhead current (depending on the position of the powerhead) and stay there for long periods. Also in the mornings when the tank room is still dark all katrias are swimming around and close to the powerhead current. They have left their calmer habitats. Perhaps this is what happens in the nature at the night time. And the dominating male is doing so sometimes most of the time. Are they sleeping at the same time? Diurnal and night time habits? It is known that for spawning Katria katria needs absolutely a calmer section but there are not enough scientific field studies about the habits of Katria katria. Having moderate and different and changeable currents and calm sections in a Mada tank is a nice study project. They are small pieces from katrias’s biotope structure. As you wrote the other possibility could be a tank with no currents at all which would resemble the most calmest sections (side-pools off the mainstream, etc.) but in the Nosivolo River, what is the water velocity between the stretches of rapids? Studying photos from Nosivolo and topographic researches and maps reveals something. Only the side-pools seem to be very calm with slow water movement. According to the collection records katrias have been found so far in the pools below rapids, between rapids in deeper pools and in the side-pools off the mainstream. Depending on many physical channel factors water can flow in a different way (turbulent currents, fast water flowing just on the upper side of the pools, slower water flowing in the pools, etc.) in the deeper pools between rapids and below rapids.

The other Nosivolo species Oxylapia polli seems to behave quite the contrary comparing to katrias. As Patrick de Rahm wrote 1996:
'In their natural habitat, Oxylapia polli appear to keep to rocky areas swept by a very strong current, which is why they are practically impossible to catch with a cast net. It is only at night that some individuals rest in shallow, quiet places. No young fishes were observed and the local fishermen were unable to tell me anything about the breeding habits of Songatana. Breeding probably takes place in the diurnal habitat of the fish, where it is practically impossible to observe. If this is so, the species must have developed special behavior in order to be able to raise its young in turbulent fast-flowing water.'


My good friend has a big tank imitating rapids from the Lower Congo. He has Steatocranus species and catfishes from different genera like Synodontis. Steatocranus species like water is moving fast and they never stay in the calmer side of the tank but they also stay away from the extreme powerhead currents with OD, always underneath as you wrote. His Steatocranus spesies are always staying at the bottom between rocks and for this reason underneath powerhead currents. One and perhaps the only reason for this habit is their swim bladder is so underdeveloped; their biotope is the bottom and rocks. In this Lower Congo tank Synodontis pardalis, S. brichardi and S. notatus swim just in the middle of the most strongest and extreme currents by powerheads and Hydor Koralia circulation pumps. And they are doing so lot, it’s their habit. In his another African biotope tank he has Tilapia snyderae which is not a good swimmer at all (anatomically) but it likes to play hours in front of the strong outlet current of the inner filter. In my 212 gallon Upper Congo river biotope tank I have two different currents (powerhead with OD and a magnum circulation pump) in the back and a calmer section in front with slower and different water flows. This is so possible to make when the tank is wide enough, mine is 30 inch (75 cm). To change the direction and power of the currents in the back and also in front I can study the behaviour of the well known Phenacogrammus interruptus, the Congo tetra and the other riverine species (they all are wild caught) whether they like and how much they like (and when they do so) moderate or faster currents or whether they prefer the calmer sections OR BOTH (there are no scientific researches about the biotopes and habitats or habits of my species. It is known SO FAR that they occur in certain rivers and their drainages). I could say that the Congo tetras are dancing in the middle of the oxygenated currents for long periods and this can happen any time a day or night. It looks beautiful and almost incredible. And they can choose their habit. This is what my Synodontis camelopardalis is also doing a lot and for long times. These are some of my examples.

My Tanganyikan tank has a large bottom area 48 x 40 inch (120 x 100 cm) and the water is circulating around the tank for good oxygen levels which is important for Tanganyikan fish species. Water is moving also at the bottom. I have oxygenated surface currents at the opposite sides in the tank and most of my Tanganyikan fish species just love that. They swim eagerly for hours just in the middle of these oxygenated flows and always in the daytimes. They are ‘eating’ oxygen drops but they are doing so in the middle of the current. Is it just the oxygen (hemoglobin adapted to high oxygen conditions) or is there another physiological reason for this habit? The night has again a story of its own.

But back to Katria katria and its biotope and habits. We know something about its biotope structure and it gives some clues about katria’s habits in the nature, maybe, but I do not know exactly. In a tank conditions (but only in a tank conditions) I can get some information about katrias’s lifestyle.

Best wishes


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Re: Katria katria in oxygenated current

Post by SergioB » Wed Sep 05, 2018 7:18 am

Spectacular text on the natural habit of Katria Katria.

The knowledge of some amateurs is impressive, which far surpasses many "experts" and vendors. I am a Spanish rookie in these boundaries, and I would love to prepare texts like this for my blog, in the category información sobre los peces, where I explain everything that I am learning from our aquatic friends.

A warm greeting for all from Spain.

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