Effect of extruded and trash fish diets on growth performance and pond productivity of the sea bream (Sparus aurata), the sea bass (Dicentrarchus labrax) and the flat head grey mullet (Mugil cephalus) reared in polyculture system in earthen ponds

Afield trial was conducted in a private fish farm consisting of six earthen ponds in order to investigate the growth performance of the sea bream, the sea bass and the feat head mullet as well as pond productivity as affected with extruded and whole fish body feeds. Sex earthen ponds each of total area of 4200m2 (feddan) represented two diets, extruded diets and whole fish bodies diet, both contained 44% protein, with three replicates for each. Fish species were stocked in each pond at densities of 3000; 1000 and 500 with an average initial weight of 11.6; 18 and 51.5g for sea bream; sea bass and mullet respectively. The experiment lasted for 14 months from start. Results obtained are summarized in the following: 1- Final body weights of sea bream and sea bass increased significantly for fish fed extruded and trash fish diets. However, for mullet final weights of fish fed on extruded and trash fish diets were insignificantly increased. 2- Final body length of both sea bream and sea bass increased significantly for fish fed extruded and trash fish diets. However, for mullet final body length of fish fed on extruded and trasli fish diets were insignificantly increased. 3- Specific growth rate, food conversion ratio and total fish production were improved with extruded diet compared with trash fish diet. 4- The highest net returns were obtained using the extruded diet