The species belonging to the genus Retroculus - currently three species are described scientifically, one additional species is still undescribed - have ever been extremely rarities in the aquarium hobby. Finally we are able to offer once more the beautiful Retroculus lapidifer from Brazil. The fish have ideal sizes (7-9 cm), but are, however, available in very limited numbers only.
Despite the similarity to the species of Geophagus, Retroculus are no closer relatives of these cichlids. Retroculus are members of a cichlid subfamily - the Retroculinae - on their own and are regarded to be the most basal living cichlids of the New World.
The swimming bladder of Retroculus is much reduced, so they are not able to hover free in the water column. In nature, these fish dwell nearby rapids. In case of danger they flee in the strongest current where almost no other fish can follow. When the danger is gone, Retroculus rest in very quiet or standing water. A good current is thus necessary in the tank (this is also necessary due to the fact that Retroculus are very sensitive against pollution), but the fish need also resting places.
The scientific name "lapidifer" means "stone-bearer", for it was known already in 1855 that these fish build nests for spawning which are made from small stones. Each stone is carried to nest with the mouth by the parent fish. Retraoculus have spawned now and then in aquaria already, it was also possible to raise some of the offspring, but to the best of my knowledge a complete natural breeding success has not been reported yet.
Retroculus should be kept always in groups (four specimens or more), otherwise they become very shy. The ground of the tank should be made mainly from fine sand, which is use by the fish quite often to search for food. Feeding Retroculus is not difficult at all, for almost any usual fish food is taken readily. The water should be soft and slightly acidic (pH 5,5 - 6,8). In the wild, water temperatures between 21.5 and 35°C have been measured in the biotopes of Retroculus, but in aquaria it is best to keep them between 22 and 28°C. The temperature may be 2° higher for breeding attempts. Retroculus lapidifer becomes about 20-25 cm long.