Tropheus duboisi Marlier 1959 male in the aquarium. Photo by Ad Konings.
T. duboisi is one of the most popular cichlids from Lake Tanganyika. Its popularity is mainly derived from the fact that juveniles have a gorgeous coloration pattern consisting of a jet-black body adorned with many light blue to white spots. The juvenile color pattern disappears when the fish gets mature and makes place for a blue-black body color with a white or yellow vertical band under the dorsal fin. The juvenile pattern, however, remains for almost a year and these fish are rightly called "Pearly Butterfly."
In the home waters of T. duboisi the biotope consists of rocks. The Pearly Butterfly is used to hide among the recesses of the rocks whenever danger threatens. In the wild, adult males do not occupy a permanent territory, as is seen in various other mouthbrooders. Most T. duboisi live in small groups or singly. They move through the habitat in search for food. Its food consists mainly of the biocover that grows on the rocks. Since T. duboisi is found at somewhat deeper levels, between 7 and 25 meters, the algae-mats on the rocks are not very lush and the fish have therefore to move from one rock to the other in order to obtain enough food. In its particular habitat the biocover may sometimes be covered with a thin layer of sediment. T. duboisi is not able to eat the algae-strands only and thus ingests the sediment as well. T. duboisi eats a lot but most of its food has a very low caloric value. To be able to digest as much as possible its gut is rather long. The gastric juices have thus ample time to digest all the food available among the large quantities of material taken in.
Tropheus duboisi Marlier 1959 juvenile in its beautiful coloration. Photo by Ad Konings.
In principle, T. duboisi is a territorial cichlid, but since it cannot find enough food in the relatively small area it could defend as a territory, it moves from one place to another. In the confinements of an aquarium, however, its behavior is adapted to the limited space and to the abundance of food that is given. In the aquarium a male T. duboisi will occupy a territory and might do this with some aggression. Females will only become territorial if there are no males in the tank. A strong female might thus become the "boss" in a tank and behave as if she were a male. Such females are difficult to maintain when a new male is introduced in the tank. If she has been the boss for a long period she might never lay eggs again. Therefore it is better to have males accompanying females.
As said before, males are territorial and each of them will occupy a small area in the tank. Since they need some objects to mark the boundaries of their territory it is desirable to accommodate a few heaps of rocks in such a way that none of these heaps have rocks in common. If you have three males in the tank, you will have to create three, separate piles of rocks. Each male will choose one pile and regard it as its territory. If there is one continuous rocky reef in your tank only the strongest male will claim the whole reef while the others will succumb his attacks. Each male needs a territory of about 75 cm in diameter. Depending on the size of the aquarium, only a few males can be kept in harmony with each other. The number of females or juvenile males is not important. It is better to have at least twice as many females than males. In my last breeding set-up I had two males and 18 females in a 200 cm. long tank with a capacity of 720 liters. It is possible to keep some other species together with the breeding colony but they should be smaller or at least subordinate to the T. duboisi .
The water in Lake Tanganyika is rather hard and very alkaline. Further it is very stable, i.e. its constitution hardly changes during the seasons. The cichlids in the lake have adapted themselves to these particular conditions, and are thus used to swim in water with a pH of about 9, a conductivity of about 600 microSiemens, and a temperature of 26.5 C . In my experience the hardness or the conductivity of the water plays a minor role, but the pH is very important. The pH of the water in the aquarium should, therefore, be in the range between 7.8 to 9.5 in order to have an optimum output by the breeding colony. If the pH is below pH 7, T. duboisi hardly breeds and is very vulnerable to all kinds of diseases. At a pH of 6.5 T. duboisi will die in a short period of time. Acidic water (a pH lower than 7) can be suited for Lake Tanganyika cichlids by adding salts. Not the regular table salt (NaCl) but carbonates. A mixture of one part NaHCO (hydrogencarbonate) and one part (carbonate) added to the water raises the pH to about 9.5. It depends on the conductivity of the water how much of this mixture should be added. You will have to experience with that. Therefore the salts are mixed before they are dissolved in the water. Such a mixture acts as a buffer; so, even if you have dissolved too much, the pH will not be higher than the pre-set pH 9.5. Another possibility is to use marine salts. These are readily available in aquarium shops. They give a pH of about 8.3, which is sufficient for T. duboisi . We give as much of this salt as is necessary to raise the pH to 8.3. Avoid making the water too salty. If the water, you start with, is very soft, you will need only a little salt. If the water is hard, but does not have the right pH, it is better to use the Na /NaHCO mixture. The temperature of the water should be between 25° and 27° C. Temperatures above 29° C are detrimental to all Tanganyikan cichlids.
One of the most important things to the well being of T. duboisi is the food we give it. As I said before, in the wild T. duboisi eats a lot of food but most of it has no digestive value. All material ingested moves at a relatively fast speed through the long gut. If we supply T. duboisi with an easily digestible food it will voraciously gobble-up as much as possible, because it is used to eat as much as possible. If the food is soft and readily digested it will form a slimy blob in the first part of the gut. It will be difficult for duboisi (and other algae-feeders) to move this slime towards the vent. The digestive tract gets upset and soon it will be unable to digest anything. The fish will get a bloating belly and loose appetite. It will be vulnerable to various diseases or just dies of the bloat. So, never, NEVER feed your duboisi or, for that matter, any other algae-feeding cichlid soft, easily digestible food. Never feed it Tubifex worms (or any other type of worms), red and white mosquito larvae or beef heart. One of the best foods to give T. duboisi is Cyclops or, to some lesser extent, Daphnia . These foods should not be given alive as parasites might be among them and affect your fish. Freeze Cyclops before you feed it to your fish. The safest choice of food is a good brand of flake food. Especially the green flakes (Spirulina flakes) are recommended but other types are good as well. Pelleted food can be used too but here you may risk obstruction of the gut. Therefore, pellets should be softened (soaked in water) before they are given. You will then see that there is quite some fine material released from the pellets. This is not eaten by the inhabitants of an aquarium and thus puts a heavy load on the filtration system. Most breeders in Europe and USA rely on a good brand of flake food, which gives the best long-term results. Another important factor concerning food is the relatively small amount of food needed daily. All artificial foods contain a high percentage of proteins so that a little amount suffices for a daily meal.
Tropheus duboisi in Kigoma bay, lake Tanganyika, Tanzania. Photo by Ad Konings.
Adult T. duboisi should be fed only once a day. It is difficult to give a quantity-per fish rule but normally so much should be given that can be eaten in ONE minute. If, after a while, the fish get thin and stop breeding a little more should be given. It is, however, more common that too much is given whereby the breeders get fat. This usually ends up in very large fish, which produce less and less eggs. The ovaries become embedded in fatty tissue and loose their capacity of making eggs. Males get bigger and more aggressive and all in the entire colony is getting more difficult to maintain. Avoid overfeeding; when flakes settle on the bottom of the tank, you have overfed.
The maintenance of the breeding tank mainly consists of a weekly water change. Depending on the amount of fish a 50% change is a regular amount. Siphon off all debris lying on the bottom and check if the filter is still operating as it should, because T. duboisi likes crystal clear water. A last recommendation: never introduce wild caught fish into an existing colony. They carry, invariably, parasites, which may be transferred to your T. duboisi . The new fish are "inspected" by the duboisis and more often than not get weaker instead of acclimatizing to the new environment. As they get weaker the parasites in them flourish and are even able to affect your healthy T. duboisi . So, never new, wild caught fish in your established breeding colony. If you have taken care of the water quality, the set-up of the breeding tank and supply the right food, there will be nothing holding T. duboisi from breeding. In an established colony spawning can be observed almost daily. Females carrying eggs and larvae can be kept together with the group or isolated in separate tanks. Never put more than one mouthbrooding female in a small tank, they will fight if two or more are kept together. If left on her own the fry will be released at the right time. The female can be put back in the breeding colony. This is best done at night when all fish are at sleep. Thus we avoid the stress of the female being surrounded by inquiring relatives while she may have forgotten the environment of the breeding tank. If one leaves the mouthbrooding females with the breeding colony, the duration of the brooding should be noted for all brood caring females because they will not release their fry in the midst of all other tank-inhabitants. After four weeks the female should be shortly placed in a tank with baby fish to induce her to spit out the fry or we may force the fry out of her mouth with the aid of a Q-tip. The easiest way to net a mouthbrooding female from the breeding tank is during the night. When all fish are at sleep we single out (with a flashlight) the female we want and effortlessly net it out. In large breeding set-ups all females could be netted out every ten days and checked for larvae. Females with eggs are placed back, they will be emptied during the next round.
T. duboisi is a beautiful cichlid which has been a mainstay in the hobby in the last 20 years. It is therefor worthwhile to put some effort in breeding these little Pearly Butterflies. Good luck!