Parasite fauna of haplochromis species (pisces: cichilidae) from Mwanza gulf of Lake Victoria

Results of a survey of the parasite fauna of Lake Victoria Haplochromis, which are currently an important fishery in East Africa, are given. Aspects investigated include: manner of infection by different parasites, factors which determine the nature and extent of infection, pathological affects on the host and identification of other possible animal hosts. Examination of nine Haplochromis species, selected from five major tropic groups, revealed the presence of five endoparasites, three of which are new in the lake and five ectoparasitic crustaceans. Two nematode larvae, Eustrongylides sp. and Contracaecum sp. occurred commonly in the body cavity of fish hosts. factors which possibly influence nematode infections are presented and discussed. Larvae of Eustrongylides were more destructive to host tissue. Early stages of the nematodes could not be traced in the invertebrates examined even though they have been implicated in the transmission of these worms. Two types of cestodes, namely, dilepidid larvae and adult proteocephalids (a new record) were isolated from the fish. The life history of the cestodes recovered from the fish hosts still remains largely unknown. A rare digenetic trematode, Allocreadiummazoensis is reported for the first time to occur in haplochromines of Lake Victoria . Mono enetictrematodes were absent during this survey. Ectoparasites encountered on Haulochromiscomprised two common gill copepods, Ergasilus lamellifer and lamproglena monodilernaea cyprinacea and two branchiurans (Argulusafricanus and Dolopsranarum) were the other crustaceans found occasionally on fish. L. cyprinacea caused the most damage to its hosts. Factors which account for the variation in prevalence and intensity of copepod infestation are discussed. This study, as a preliminary one indicates that further work is needed to explain some of the unresolved issues. The results do however show the nature and extent of the metazoan parasite fauna of Haplochromis from Lake Victoria.