HAEMATOLOGICAL AND HISTO-BIOCHEMICAL INDICES OF AFRICAN CATFISH (Heterobranchus bidorsalis) FED NIGELLA SATIVA SEED EXTRACT

The aim of this study was to determine the haematological and histo-biochemical indices of African catfish (Heterobranchus bidorsalis) juveniles fed Nigella sativa seed extract. The fishes were fed with a formulated diet supplemented with extract at 0.0g/kg, 1.0g/kg, 1.5g/kg, and 2.0g/kg inclusion level (representing treatment groups: TC, T1, T2, and T3, respectively) for 28 days under laboratory condition. Sampling was done on the 28th day; 15 fish (5 from each replicate) were harvested and anesthetized using clove oil; a blood sample was drawn from each group via caudal peduncle puncture using a disposable needle and syringe; later emptied into ethylene diamine tetraacetate (EDTA) bottles to prevent clotting and kept for haematological analysis. Haemoglobin (Hgb) was determined using the cyanomethemoglobin method. Red blood cells (RBC) and white blood cells (WBC) were counted by Naubauer’s improved haemacytometer using Hyem’s and Turk's solution as diluting fluids, respectively. The haematocrit method was used for the estimation of packed cell volume (PCV). The mean corpuscular haemoglobin (MCH), mean cell haemoglobin concentration (MCHC), and mean cell volume (MCV) were calculated. Kidney and liver of the fish were excised, cleaned of extraneous tissues in phosphate buffer solution then immediately snap frozen in liquid nitrogen; then stored in an ultra-low freezer (−86°C) for biochemical analysis. Haemoglobin levels ranged from 11.97(g/l) to 13.12(g/l). Treatment groups TC and T1 showed no significant differences (p > 0.05) in the levels/concentrations of Hgb, RBC, WBC, and MCH; similarly, the treatment groups T2 and T3. Decreased histo-biochemical parameters (ALP, ALT, AST, creatinine, and urea nitrogen) levels in H. bidorsalis fed Nigella sativa-supplemented diets, when compared with those fed a basal diet, were recorded; this indicates that the treatment group (T3-2 g/kg) was found to be most effective. This study, therefore, recommends the use of Nigella sativa-supplemented diets at an inclusion level of 2 g/kg in aquaculture practice.