Nigriventris are found on the Congo side of Lake Tanganyika, in an area between the village of Tembwe and the village of Lunangwa. This is of course in Africa.
Wild males are reported to grow to about four inches in length. My breeding male is about four inches long, and has not grown in a while. The females are about a half an inch smaller.
The water in lake Tanganyika has a PH of between 8.6-9.5. The general hardness (GH) in the lake measures about 15 (280ppm) and the carbonate hardness (KH) about 12 (240ppm). The temperature is 76-82 degrees F. My tank currently has a GH of 16, a KH of 13, and a temp of 78.
I house a breeding trio in a tank with a base dimension (height matters little) of 19 inches by 36 inches. I think a single pair would work in a 20 long. Each fish has a distinct territory. If the territories are too cramped aggression could be heavy.
Nigriventris live at a depth of about 24 feet, in an area of rock and sand. Like most africans they like to dig and need caves to feel secure in the home aquarium.
The stomach contents of wild fish included: crustaceans, insect larvae, copepods, snail fragments, algal strands, and sand grains (buscher,1991,1992d). In my aquarium they are fed a high quality flake mix, and occasional shrimp(adults will still eat live baby brine).
I have not found much about their behavior in the wild. My fish are scared easy by fast movement around the tank, but are very content to let you watch them if you are still. They tend to hang out around their cave most of the time. The male moves around the most, surveying his harem. Occasionally the female does not like this intrusion (if she has young babies or eggs) and she will chase him out (or attempt to). The females do not allow the other female into their territory. Although the male has little to do with guarding the young he doesn’t try to eat them. Even older siblings are tolerated. They don’t seem to attempt to eat the babies either. When I was first trying to get them to breed, I offered small guppies as a live food, but they left them alone.
Nigriventris are basically sexually isomorphic. This means that when you look at a group of them it would be nearly impossible to pick out the males from the females. If you had a fully mature group, the bigger ones would probably be the males.
Breeding this fish takes a little more effort and patience. I did not know that they had bred the first time, until I saw about three week old fry near the breeding cave (they hid well in the gravel). The female is often near or in her cave. This behavior is about the same whether or not she has eggs. You pretty much have to wait for the babies to come out before you know they are there. Water quality is more important to breed nigrivenris that other africans. Good water and good food are important. At least one cave per fish should be spread out in the tank. I have never seen the male and female in the cave together. The male does not hang around after he fertilizes the eggs. The pair will usually test each other prior to each breeding. This means they will quarrel a lot. It is said that they are testing the strength and health of a potential mate. Nigriventris seem to have fairly small clutches so don’t expect to flood the market.
Nigriventris will guard a cave and may chase others away, but they don’t seem to have interest in beating up other fish. I don’t know that I would put them with angelfish, but they didn’t eat the small guppies I offered them. A light colored sand or gravel seems to best show off their colors.
Nigriventris are one of my favorite fishes. They have a lot of subtle colors that are not always visible in photographs. One interesting side note: as the young grow they stay in the territory of their mother even at 1-½ inches. The two older batches (from different mothers) do not mix. Here are some pictures.
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