Length-Weight and Length-Length Relationships with Condition Factor of three Commercial Fish Species from River Niger, Itobe, Kogi State, Nigeria

The Lower River Niger at Itobe is one of the key sources of livelihood to many communities, as it supports large artisanal fisheries for teleost species. This study evaluated the length-weight relationship (LWR), length-length relationship (LLR), condition factor (K), and size-frequency distribution of three economically important fish species in the Lower River Niger at Itobe, Kogi State, Nigeria. The morphometric measurements of total length, standard length, and body weight of Clarias gariepinus, Oreochromis niloticus, and Synodontis batensoda were obtained using standard fisheries procedures. The LWR and LLR were computed using linear regression, while the condition factor (K) and size-frequency distribution were used to determine the fish condition and population structure, respectively. The growth coefficient (b) values for C. gariepinus, O. niloticus, and S. batensoda ranged from 1.75-2.40, 2.29-2.87, and 2.54-2.69, respectively, indicating negative allometric growth (b < 3). Significant sex differences were recorded for C. gariepinus (p = 0.040) and S. batensoda (p = 0.013), but not for O. niloticus (p = 0.140). Condition factor values ranged from 0.9-1.2, with the highest value recorded for female C. gariepinus. A strong positive LLR was observed (r = 0.849-0.938). The size-frequency distribution showed that small and medium-sized fish species dominated the distribution, with few large fish species, suggesting that the length increases faster than weight.