Effect of different levels of protein diets on growth performance of African catfish (Clarias gariepinus Burchell, 1822) fingerlings in tanks

Abstract

The growth performance of African catfish, Clarias gariepinus fed on three levels of protein diets (30% CP, 35% CP and 40% CP) formulated from plant, animal and agro-industrial by-products were experimentally evaluated in recirculating tanks. A total of nine tanks, each with 1 m³ volume were used in the feeding experiment. The experiment was conducted in triplicate tanks at a stocking density of 12 fish fingerlings per tank. Before the commencement of the actual experiment, stocked fish were left to acclimatize in their tanks for a week. All fish were fed 5% of their body weight per day, and the ration was given twice a day in the morning (10:00 am) and afternoon (4:00 pm) for all treatment groups. The initial total length (TL) and total weight (TW) of each fish was measured to the nearest 0.1 cm and 0.1 g, respectively. Similarly, monthly TL and TW of all fish were measured to compute the growth rate and adjust the daily ration accordingly throughout the experiment period (January 2019 to July 2019). Some physico-chemical parameters of the tank water including dissolved oxygen, water temperature, pH, conductivity as well as level of ammonia were recorded. The results of the experiment showed very significant variations on the growth of fish between the treatment groups (p<0.05). Fish fed with 40% crude protein showed the highest daily growth rate (0.52 g/day) followed by fish fed with 35% CP and 30% CP. Similarly, the lowest feed conversion ratio (FCR=2.1) was recorded in fish fed with 40% CP, indicating its suitability for African catfish fingerlings than the other test diets. The overall survival rate varied from 85.2%–92% per treatment. The physico-chemical parameters of the rearing tanks were close to the lower limits of DO and water temperature required for the growth of African catfish. The low daily growth rate of C. gariepinus observed in this study might be attributed to the combined effects of low quality of the test feeds and poor water quality recorded in rearing tanks.