Length-weight relationship and condition factor of Mugil cephalus and Oreochromis niloticus from a Tidal creek in the Niger Delta, Nigeria

Abstract

The aim of this study was to assess the length-weight relationship (LWR) and condition factor (K) of Mugil cephalus and Oreochromis niloticus obtained from a tidal creek in the Niger Delta Nigeria. Six samples of each species were randomly collected monthly (January – December 2015) from fisher men making a total of 144 samples. Samples were immediately taken to the laboratory in ice pack coolers for analysis. The b-values ranged from 0.913-3.172 and 1.624-3.484 while K-values ranged from 0.79-1.07 and 1.01-1.08 for M. cephalus and O. niloticus respectively. The results indicated positive and negative allometric growth patterns (b>3 & b<3) for the two fish species, a departure from the cub law, but M. cephalus exhibited isometric growth pattern (b=3.003) during just one month of the study period, a compliance with the cube law. Growth coefficient also had obvious inter and intra specific variation while condition factor did not but indicated wellbeing of fish samples examined. The weight of both fish showed significant difference (P<0.01/ P<0.05) with respect to time while R² values indicated strong linear relationship between length and weight. The study concluded that allometric growth pattern observed for the two fish species had both inter and intra specific variation along temporal lines. However, inter and intra specific condition of fish examined was relatively stable across study period suggesting the two different species could have responded to ecological and environmental variables similarly.