Most aquarium fishes exported from Lake Malawi are cichlids of 10 rock-frequenting genera collectively referred to by their Chitonga name, Mbuna. These fishes provide a classical example of intralacustrine allopatric speciation. The distribution of 196 species is given with notes on habitat preferenda, depth distribution and behaviour. Considerable emphasis is placed on coloration and markings for identification and it is argued that they are important for mate recognition. Brief notes are given on some of the other rocky shore fishes particularly in the genus Cyrtocara. The value of the aquarium fish resource resides principally in its species richness. Most Mbuna species are geographically restricted and stenotopic. The majority occur in the upper 20 m. Mbuna are trophic specialists, but have the ability to feed opportunistically on a variety of food resources. Resource partitioning is effected by different trophic groups. Evidence suggests that species within a particular trophic group which feed upon apparently identical food material, collect it from different microhabitats.

Two species of Labeotropheus are currently recognized, but an earlier study of aquarium specimens caused doubt to be cast upon their specific distinctness. This doubt was removed by a field and laboratory study which showed that L. fuelleborni differed from L. trewavasae morphologically, in coloration, in geographic distribution, preferred habitat and ability to penetrate depth. The two species practise assortative mating. Labeotropheus fuelleborni feeds predominantly from upper surfaces of rocks while L. trewavasae favours under surfaces. Although both species are specialized to crop epilithic algae they also feed secondarily on other food resources (e.g. plankton, insects) when these are available. Gene flow between many populations of rock-frequenting cichlids is restricted by their sedentary nature and apparent inability to cross open water between rocky areas. Consequently, numerous geographic races, incipient species and species are found in the lake. This suggests that intralacustrine allopatric speciation may account for much of the species diversity of cichlids of rocky zones. It is recommended that biologists working on cichlids from Lake Malawi should ascertain the precise location at which their specimens were caught and avoid using aquarium reared fish.

The number of species of cichlid found to host foreign offspring in mixed broods in Lake Malawi is much greater than originally supposed. It is suggested that all species which show well developed parental behaviour may have foreign fry mix with their broods on occasion. A variety of species of fry were found in mixed broods. These come from two categories of fish: those which apparently do not guard their free swimming fry; and those which have a well entrenched phase of protective care. Although substrate spawners may encourage other fry to join their broods it is argued that foreign young are unwelcome guests of mouthbrooders.Die aantal spesies van die Cichlidae in die Malawi-meer wat vreemde kleintjies in gemengde skole beskerm is baie meer as wat aanvanklik veronderstel is. Daar word voorgestel dat alle spesies met goed ontwikkelde ouersorg by tye vreemde kleintjies tussen hul eie sal hg. Hierdie vreemde kleintjies is afkomstig van twee kategoriS van visse: die wat nie hul vryswemmende nageslag klein vissies oppas nie; en die wat 'n goed gevestigde tydperk van beskerming het. Alhoewel visse wat op die bodem kuitskiet ander klein vissies kan aanmoedig om by hulle kleintjies aan te sluit is dit twyfelagtig of vreemde kleintjies welkom sou wees by mondbroeiers.