Effect of dietary protein level on growth and body composition of juvenile spotted sand bass, Paralabrax maculatofasciatus, fed practical diets

A preliminary feeding trial was made to determine the effect of dietary protein level on growth and body composition of juvenile spotted sand bass Paralabrax maculatofasciatus (9.5 g). Fish were randomly distributed in nine 600-1 circular tanks (42 fish/tank), which were connected to a closed water recirculating system. Fish were fed practical diets for 93 days containing increasing protein levels (40%, 45%, and 50%). Significant lower weight (P < 0.05) was observed in fish fed the 40% protein diet (43.1 g) compared to fish fed higher proteins diets. Growth rates, evaluated by an exponential model Y = ae ^bX, and gross energy retention (GER) were significantly higher in fish fed the 45% and 50% protein diets than the fish fed the 40% diet (P < 0.05). No significant difference among dietary protein levels was detected for the other growth variables measured, nor for the proximate composition of the whole fish, liver, or muscle. The use of a practical diet containing at least 45% protein is appropriate for growth of spotted sand bass juveniles.