Survival rate, growth and condition index of tank-raised Clarias gariepinus under different salinities

The study evaluated varying levels of salinity on survival, growth and condition index of tank raised Clarias gariepinus for ten weeks. A total of 120 healthy C. gariepinus fingerlings having a bulk weight and average length of 131.73 ± 0.85 g and 5.06 ± 0.24 cm respectively were procured from the hatchery complex of University of Calabar fish farm and used for the study. Sea water was collected from Ibeno Beach and diluted with borehole water to obtain various salinity concentrations of ≤1, ≤5, ≤10 and ≤15 ppt. This represented four treatments(Tanks A to D) and each treatment had three replicates. Evaluation of growth indices and culture water parameters followed standard procedure. Results revealed significant (p < 0.05) differences with regards to food intake in the treatment Tanks A (≤1ppt), B (≤5ppt), C (≤10ppt) and D (≤15ppt). Food conversion efficiency (FCE), ratio (FCR) and protein efficiency ratio (PER) were significantly different (p < 0.05). Body weight gain were observed to be higher in Tank A with a value of 75.83± 0.07g/kg and a total length of 11.13 ±0.38cm and the lowest weight gain was recorded in Tank D with a value of 43.56 ± 0.76g/kg and a mean total length of 6.67± 0.43cm. There were significant differences (p < 0.05) in the final condition factor (K) of the fish. Hence, it could be established that C. gariepinus fingerlings can survive and be reared in 5ppt saline water without any adverse effect on growth. At salinity level above 5ppt, fish growth rate may be slow. Keywords: Survival rate, Growth, Clarias gariepinus, Salinity, Physicochemical parameters