Feeding habits and some biological aspects of fish species in gilgel gibe reservoir, omo-turkana basin, ethiopia

Relative abundance, feeding habits, length-weight relationships and conditions factors of two fish species from Gilgel Gibe reservoir, Ethiopia, were investigated. Percentage index of relative importance (%IRI) was used to investigate relative abundance of the fish species. Frequency of occurrence and volumetric methods were used in analyzing feeding habits of the fishes. However, an index of preponderance was used to assess relative contribution of prey items to the fish diets. The diet breadth index (BA) values (O. niloticus = 0.40 & L. intermedius = 0.63) suggested an omnivorous feeding habit for both fishes. The Horn’s overlap index (44 %) indicated considerable prey overlap between the two species. The feeding habit of O. niloticus did not vary between seasons. The lines of best fit to the regressions of log transformed Weight-Total length had the equations of a form log W = 2.76 log TL-1.40 (R2 = 0.89) for O. niloticus and log W = 2.24 log TL-0.79 (R2 = 0.59) for L.intermedius. Seasonal variations in ‘b’ and condition factors as well as dependence of the latter on fish size were also investigated. The findings of the present study are of functional value in the proper management and exploitation of the reservoir’s fishery resource.