Length-Weight Relationships and Condition Factors of Several Nigerian Fish Species

Abstract

The length-weight relationship and condition factor of Sarotherodon galilaeus and Oreochromis niloticus were observed in Strabag Lake. A total number of 365 individuals of the fish species were caught during the period of study with Sarotherodon galilaeus constituting 65.21% of the total catch while Oreochromis niloticus made up 34.79% of the catch. The mean weight (W) and mean total length (TL) were 56.04 ± 1.019 g and14.64 ± 0.103 cm respectively for S. galilaeus;62.86 ± 2.184 g and15.84 ± 0.171 cm respectively for O. niloticus. The values of constants a and b (growth exponent) were determined from the length and weight data which transformed into the linear equation of log W = log a + b log L. These parameters were then fitted to the exponential equation, W = [aL]b. The respective exponential equation for the length-weight relationship was W = 0.068[L]2.5 for S. galilaeus and W = 0.034[L]2.7 for O. niloticus which shows that both species exhibited negative allometric growth (b < 3.0). The correlation coefficient (r) and condition factor (K) recorded were 0.944 and 6.70 respectively for S. galilaeus and 0.911 and 3.49 respectively for O. niloticus specimens. The species showed negative allometric growth and were thriving well in the environment.