Fingerlings of Clarias gariepinus were used to evaluate the effect of dietary fumonisin B1 (FB1), a mycotoxin produced by Fusarium verticillioides, on growth, haematological and serum biochemical parameters. The fingerlings were sorted, weighed and randomly stocked in 16 plastic tanks at the rate of 20 fingerlings per tank. Fusarium-cultured maize grains containing FB1 were used to formulate three diets containing approximately 5.0, 10.0 and 15.0 mg FB1/kg, constituting diets 2, 3, and 4 respectively. These three diets, plus diet 1, which contained non-Fusarium cultured maize grains that served as the control, were used in a 6-week feeding trial. The final weight gains by the fingerlings were significantly (P < 0.05) influenced by FB1. The final weights of the fingerlings fed diets 2, 3 and 4 ranged from 70.07 to 87.10% of the controls. The haematocrit, erythrocytes, haemoglobin, mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH) and the serum protein constituents (total protein, albumin and globulin) values significantly (P < 0.05) decreased, while the leucocytes, MCV and MCH increased significantly (P < 0.05) with increase in the dietary FB1. The total serum protein values of the fingerlings fed diets 2, 3 and 4 were 34.53, 39.42 and 50.17% lower than the total serum protein values of those fed the control diet. These results indicate that Fusarium-contaminated diets containing about 5.0 mg or more FB1/kg reduced weight gain and significantly altered haematological parameters and serum protein constituents in the fingerlings. These may have a significant impact on physiological activities and may be vital in immunosuppression in the fingerlings with a strong negative impact on subsequent performance of the fish.

Synthetic antibiotics have been widely used in fish culture systems as performance enhancers and controlling stress.These antibiotics are expensive and induce microbial resistance with consequent environmental effects. Phytogenic plants have potential as alternative antibiotics, but there is little information on their utilization in fish nutrition. Therefore the evaluation of Basil (Ocimum gratissimum) leaf meal on the growth response, nutrient utilization and production economics of Clarias gariepinus. In a 12 week feeding experiment, juveniles (n =20, weight:10.94±0.02 g) were used to assess the effect of different concentrations of Ocimum gratissimum at OGM1-OGM6; (0.00; 0.125; 0.25; 0.5; 0.10; 2.00%). A total of 120 fish were randomly allotted into treatments in triplicates, fed twice daily at 5% body weight in completely randomized design. Data for the growth and nutrient utilization parameters such as: Total weight gain (TWG), Total final weight (TFW); Mean weight Gain (MWG), specific growth rate (SGR), feed conversion ratio (FCR); and economic indices such as profit indices, (PI), were determined. Data were analysed using descriptive statistics and ANOVA at α 0.05 . The highest TWG and FWG (916.67 ±17.98 g; 698.83±17.54 g) was from the fish fed OGM2 diet and the least (137.92±2.97 g; -81.08±2.97 g) from fish fed OGM6 diet. While the highest MWG was from fish fed OG3 diet and the least was from OG6 diet. The fish fed OGM3 had the highest PI (5.72) and the least (1.53) was from fish fed OGM6 diet. Therefore adoption of Ocimum gratissimum meal diet at the established dosages of OGM2 and OGM3 in sustainable catfish production in Africa is being advocated based on its availability and profitability.

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