Helminth fauna of Oreochromis leucostictus (Pisces: Cichlidae) from a tropical lake, Lake Naivasha, Kenya

The helminth fauna of Oreochromis leucosticus (Trewavas) from Lake Naivasha is described. The study was carried out on 1,050 gillnetted fish caught over a period of 24 months at different sites within the lake. Oreochromis leucosticus which is a commercially important fish was observed to be a host of four helminth parasites. These were an acanthocephalan polyacanthorhynchus kenyensis (Schmidt and Canaris), a nematode contracaecum sp.. a trematode clinostomum sp. and a dilepidid cestode Amirthalingamia sp. Seasonal variation in prevalence, intensity of infection, organs infected and the variation in infection with the size, sex and body condition of the host are described. There was no seasonal variation in prevalence but intensity of infection was observed to increase with the age of the fish. Although male fish were observed to be more heavily infected, the parasites did not seem to have any significant effect on the body condition of the fish

Current state of the fish stocks of Lake Victoria (Uganda)

A total of 561 hauls were taken during experimental bottom trawl surveys in the Uganda sector of Lake Victoria during the period November 1997 to December 1999 to estimate composition, distribution and abundance of the major fish species in waters 4-60 m deep. Seventeen fish groups were caught with Nile perch, Lates niloticus (L.), constituting 90.02% by Weight. Haplochromines and L. niloticus occurred in all areas sampled while. Nile tilapia, Oreochromis niloticus(L.)and other tilapiines were restricted to waters <30 m deep. The mean trawl catch rate in the zone where artisanal fishermen operate (i.e. in waters<30mdepth)was 169.94·kghr-1,ofwhich90.24%was L. niloticus. Species diversity and relative abundance decreased with increasing water depth