Effect of the replacement levels of soya bean meal by water Hyacinth flour (Eichhornia Crassipes) as a source of protein on the survival and some zootechnical performances of Clarias Gariepinus fry in concrete tanks

In order to contribute to the increase of table fish production in the world in general and particularly in Cameroon through an optimal valorization of local by-products, the zootechnical performance of Clarias gariepinus fry was evaluated in concrete tanks according to the replacement levels of soya bean meal by water hyacinth flour (Eichhornia crassipes). For this purpose, a trial was conducted at the Logbaba Intensive Aquaculture Pilot Unit (LN: 4°02’ and 4°34’; LE: 9°41’ and 9°18’). A total of 240 Clarias gariepinus fry of initial mean weight 5 ± 0.22 g were divided into 12 batches of 20 fry each into 0.5 m3 baits in concrete tanks in a completely randomized device. These fries were fed for 56 days. The feed rations consisted of 4 iso-protein feeds with 47% protein. Either T0+ (positive proof) an imported food (Coppens), T0- (Negative proof) local food without soya bean meal and two other experimental foods whose soya bean meal has been replaced at 5% (T5) and 10% (T10) by Eichhornia crassipes flour. The results obtained showed that the highest survival rate (98.33% ± 2.88%) was recorded with the imported feed T0+ and lower (93.33% ± 2.76%) with the food containing 5% water hyacinth powder. The final mean weight and daily weight gain were significantly (P < 0.05) higher (26.08 ± 1.25 g and 1.49 ± 0.08 g/d respectively) with the T0+ diet and lower with the T1 local food (11, 92 ± 0, 90; 48 ± 0,06 g/d respectively). The average daily gain was comparable between the T5 and T10 diets (0.67 ± 0.14 g/d; 0.93 ± 0.12 g/d respectively). The specific growth rate (P < 0.05) and consumption index (P < 0.05) were significantly higher (2.87 % ± 0.08% g/d and 0.34 ± 0.04 respectively) compared to treatments containing 5% (T5) and 10% (T10) of water hyacinth powder (1.83 ± 0.24 g/d; 2.24 ± 0.17% g/d) and 1.08 ± 0.31; 0.66 ± 0.14) respectively. Thus, water hyacinth flour can be used to replace the soya bean meal as a protein source in the diet of Clarias gariepinus fry for optimal growth.