EFFECT OF PARTIAL AND TOTAL REPLACMENT OF DIETARY FISHMEAL WITH FERMENTED FISH SILAGE ON GROWTH, PRODUCTION AND DIGESTIBILITY IN SOME FRESHWATER FISHES

The effects of partial and total replacement of dietary Commercial fish teal (CFM) with fermented fish silage (FFS) on growth performance, digestibility coefficient and proximate composition were examined in three freshwater fishes namely, tilapia (Sarotherodon galilaeus), common carp (Cyprinus carpio) and African catfish (Clarias gariepinus). The fish had a starting weight of 50, 55 and 57g respectively and reared in concrete ponds (20 m2) at a rate of 6 fish/m2 (1:1:1) for 180 days. The diet containing 60 % CFM and 40 % FFS was suitable to tilapia species. where the highest total weight gain (168.5) and optimum feed conversion ratio (2.92) were obtained. Nutrients digestibility had also their best percentages (78 % for proteins, 76 % for fats and 57.5 % for carbohydrates) at the same dict. Consequently, the production and profitability reached their maximum values (1835.4 kg/feddan and 0.94 %) and the proximate composition of fish was improved. Common carp preferred diet containing 80 % CFM and 20 % FFS at which the total weight gain (TWG), specific growth rate (SGR) and normalized biomass index (NBI) had their highest values (196.5 g, 0.57 and 1.97). Feeding on the same diet showed maximum digestibility for proteins, fats and carbohydrates (81.5%, 71.0% and 61.5%) in fish body. The total production and profitability were also increased to 2112.6 kg/ feddan and 0.50 at 20 % FFS level in dict. The proximate composition (wet weight basis) and energy content of C.carpio were also improved where the protein, ash, gross energy und protein 2 energy ratio values reached to 23.0%, 3.3%, 8.01 kj/g and 120.17 respectively, while fat content decreased to 6.5%. In catfish, the growth performance had its highest value with diet containing 20% CFM and 80% PFS, where total weight gain specific growth rate and normalized biomass index were 238.52, 0.92 and 2.39%. Also, feed conversion ratio (PCR), protein efficiency ratio (PER) and protein productive value (PPV) had its best values (2.77. 1.20 and 2.39). With the same diet the digestibility of proteins, fats, carbohydrates and energy showed its highest values (87.5%, 84.0%, 66.5% and 0.5%), consequently the production and profitability of fish recorded its maximum values (2482.2 kg/feddan and 0.76%). The proximate composition of soft tissue (wet weight basis) in catfish was significantly influenced by fermented fish silage levels in diets where the protein, ash und energy contents were increased, while fat decreased in fish bodies.