Water quality parameters and length-weight relationship of <i>Bagrus bajad</i> (Fabricius, 1775) in Ajiwa Reservoir, Katsina State

Continuous assessment of natural water bodies is essential to ascertain the pollution and health status. This study was conducted between February and September 2022 to evaluate the physicochemical parameters and the length-weight relationship of silver catfish in Ajiwa Reservoir, Katsina State with the aim of evaluating the pollution and health status of the water body. Temperature, pH, dissolved oxygen (DO), water hardness, turbidity, alkalinity, and total ammonia-nitrogen were evaluated using standard techniques. Length-weight relationship of silver catfish was also assessed. One-way ANOVA was used to compare each of the physicochemical parameters among three sampling stations in the reservoir. Linear regression was used to fit the length-weight relationship model and Fulton’s condition factor for wellbeing of the fish. All the water quality parameters were similar among the three stations except total ammonia-nitrogen (TAN) 8.82±0.02 mgL-1, which was significantly (P<0.05) higher in Kadaji compared to the two other stations. Monthly variation was also observed in all the examined water quality parameters. The length-weight relationship of Bagrus bajad during the study period showed negative allometric growth as the slope parameter (b) value ranged between 0.85 in Gamji to 1.16 in Kadaji. However, the fish were in good condition as the combined K value was 1.02 and each of the stations had K values between 0.92 and 1.10. The water body cannot be said to be under pollution stress considering all the physicochemical parameters were within the recommended level for tropical fish species and the K value revealed that the fish are in good condition.