Abstract

This study evaluated the Length-Weight Relationship of four commercially available fish species (Coptodon zillii, Oreochromis niloticus, Chrysichthys nigrodigitatus and Brycinus nurse) of Oyan Lake. Eighty adult individuals of each fish species were procured from fishermen in Oyan Lake over a period of 4 months. The fish species were put in sterile polythene bags and taken in icebox to the laboratory. Weight and length of individual fish were measured using Metler balance and a measuring board respectively. Length–weight relationship was analyzed using the equation W=aL^b. The condition factor of the fish species was determined using the equation, K=100W/L^b. The female fish species recorded higher mean Total Length (TL) and mean weight (Wt) in all four fish species examined. However, there was no significant difference (P>0.05) in the mean total body length, mean standard length and mean body weight between the female and the male fish species. The length-weight relationship was observed to be significantly strong (P=0.01) in all the four fish species evaluated with Coefficient of determination (R2) and the Correlation co-efficient (r) ranging from 0.893 to 0.991. The condition factor (K) was higher in Coptodon zillii, followed by Oreochromis niloticus, Brycinus nurse and Chrysichthys nigrodigitatus. The growth pattern of Chrysichthys nigrodigitatus was Positive Allometric while the growth pattern of Coptodon zillii, Oreochromis niloticus and Brycinus nurse were Negative Allometric.

Keywords: Fish; Length; Growth pattern; Bioaccumulation