LENGTH-WEIGHT RELATIONSHIP

ABSTRACT

A morphometric study to assess the length-weight relationships, condition factor and sex ratio of two (2) freshwater fishes namely Brycinus nurse and Synodontis violaceus,belonging to the families Alestidae and Mochokidae respectively was conducted in Ovia River (Iguoriakhi), Edo state, Nigeriaover a period of 6 months, August, 2021 – January, 2022. Morphometric measurements such as Total Length (TL), Head Length (HL), Standard Length (SL), Body Depth (BD) and Body Weight (BW) were taken and recorded for each specimen in the laboratory. The range of the standard length and body weight of Brycinus nurse was from 12.8-26 and 57.7-367.1 respectively while, that of Synodontis violaceus was from 11.5-19.5 and 59.8-262.4 respectively. The length-weight relationship showed that the species’ weight were relatively highly regressed on length (p < 0.05) with Coefficient of determination (R²) and the Correlation co-efficient (r) being 0.9712 and 0.9855 respectively for Brycinus nurse while, 0.4291 and 0.6551 was for Synodontis violaceus. The growth coefficient (b) was 2.5573 and 0.8244 for Brycinus nurse and Synodontis violaceus respectively. There was no significant difference (p > 0.05) in k-factor of the specimens sampled across the duration of the study for both species. Mean sex ratio for Brycinus nurse was recorded to be 0.85:1 and 2:1 for Synodontis violaceus. Results show that both species exhibited negative allometric growth. The mean condition factor (K) values across the sampling period were all greater than 1.0 for both species, hence, the fishes are in good condition.