Effect of Diplostomum species on length-weight relationship of farmed nile tilapia in Kibos area, Kisumu City, Kenya

Abstract

Diplostomum species metacercariae are parasitic trematodes that pose significant economic threat to fish farming worldwide. Nile tilapia ranks the most commercialized fish in Kenya besides being a cheap source of highly nutritive protein. However, low production of pond reared Nile tilapia in western Kenya poses threats to initiatives by the Kenyan government to revamp the economy of residents in this region. Diplostomiasis infection has been scantly reported in the region, however, comprehensive studies on the effect of Diplostomum spp. on the health status of farmed fish is lacking. This study examined the influence of Diplostomum parasites on the length-weight relationships and condition factor of farmed tilapia in Kibos area near Kisumu City. 326 fish samples were collected from three fish farms between December, 2011 and February, 2012. The values of the regression co-efficient obtained for the length-body weight relationship in all the farms was around the hypothetical value '3' whereas the correlation co-efficient was greater than 0.9. This suggests an isometric growth form in all the sampled specimens. The condition factor computed exhibited values significantly greater than [K.sub.n] = 1.0. There was no significant statistical difference (p 0.05) between parasitized and non-parasitized fish. Thus, it is clear the specimens were healthy and fingerlings ( Keywords: Condition factor; length; weight; Oreochromis niloticus; pond.