Dietary protein requirements for juvenile sole Solea aegyptiaca (Chabanaud, 1927)

The present study was conducted to determine the dietary protein requirement for optimal growth performance and body composition of juvenile sole fish. Four diets were formulated with different protein levels (D40, D45, D50 and D55% crude protein). The silverside fish (Atherina boyeri) was added to the diets as local animal protein source and to enhance palatability of the test diets. Fish were fed the artificial diets as 2% of the fish biomass daily divided into two equal portions. Juvenile sole with an initial weight of (6.65±0.2g) were distributed as 40 juveniles in each triplicate tank, each of 1m^3 volume. The experimental period lasted 120 days after start. The results showed significant differences (P 0.05) in growth performance and feed efficiency between diets. The highest performances in terms of (Finial weight, Weight gain, Average daily gain, Specific growth rate, Condition factor, Feed conversion ratio, Protein efficiency ratio, Protein productive value and Hepatosomatic index) were obtained with the D55% CP, followed by D50%, without significance difference between them. However, fish fed D40% crude protein diet recorded less performance parameters. No significance difference (P 0.05) in whole body chemical composition (dry matter, crude protein, crude lipid and ash) were found between fish fed all experimental diets. However, slight increase in whole body lipid contents were recorded with D50%CP and D55%CP levels. The results of the present study indicated that, D55% crude protein level can be optimal for meeting the requirement of juvenile sole, Solea aegyptiaca without adverse effects on growth performance and feed efficiency.