The factors that determine parasite assemblages among the clariid fishes of
Lake Victoria, Tanzania were studied between August 2003 and February 2005.
Six hundred and fifty-six fish belonging to seven species were necropsied and
examined for parasites, from which 31 species of metazoan parasites were
recorded. The community was dominated by the nematodes both in species and
numbers. Most species were generalists with only two trematodes, Diplostomum
mashonense and Tylodelphys species, being specialists of Clarias gariepinus. Ten
species were considered core and predictable. Parasite species richness, number
of individuals per host and Shannon–Wiener diversity indices were generally
high. At the compound community level, a mean number of 7.8 parasites were
shared among different species of fish and the maximum number of parasites
species per fish at the infracommunity level was seven. Levels of similarity in
parasite species richness at the component community level ranged from 29.6 to
61.5%. The study concludes that parasite communities in clariid fishes of Lake
Victoria are structured by ecological factors. At the infracommunity level, host
size, diet and vagility promoted a richer parasite community. At the compound
level, two factors were crucial, namely the intermixing of the waters in the lake
and the predominant and mobile C. gariepinus.
Lake Victoria Environmental Management Project (LVEMP I)