The use of ocean-caught fish to produce fishmeal as a source of protein for aquaculture feed threatens ocean-caught fish stocks and biodiversity and creates economic uncertainty for aquaculture businesses. Therefore, t hree feeding trials were conducted to evaluate the replacement of menhaden fishmeal protein (MFP) by single cell protein (SCP ) Methylorubrum sp meal (Trial 1) , Salicornia virginica (sea beans) , a halophyte plants meal (Trial 2) and a combination of non-conventional and conventional protein sources (Trial 3) in the diets of juvenile black sea bass Centropristis striata. In trial 1, 2 and 3, a total of 21 iso-nitrogenous (48% crude protein) and isolipidic (13%) test diets (eight , seven and six, respectively) were formulated and prepared replacing graded levels of MFP by supplementing SCP meal, Salicornia meal and a combined alternative protein sources, respectively. Fifteen juvenile fish were stocked in each 75-L tank in a recirculating aquaculture system and each test diet was fed twice a day to triplicate groups of juvenile fish for 8 to 10 weeks.
The diets proximate, amino acids and fatty acid profiles and g rowth performance, feed utilization and body biochemical compositions of fish were evaluated after the feeding trials . In trial 1 and 2, supplementing SCP and Salicornia meal up to 30% and 25%, respectively did not affect on growth performance as compared to the control diets. In trial 3, supplementing 10% SCP with a combination of conventional and non-conventional alternative protein sources showed better performance, in terms of growth and body composition as compared to other test diets. Survival was higher than 90% among the treatments with no significant differences for all three trials. Results to date suggest that black sea bass juveniles are able to utilize high levels of SCP and Salicornia meal without affecting fish growth. With the supplement of SCP, a combination of alternative protein sources could be used to formulate an eco-aquafeed for the juvenile black sea bass reducing the amount of fishmeal protein in the diets.