Performance of crustacean and insect meal based diets on the growth and digestive enzyme profile of pearlspot Etroplus suratensis  (Bloch, 1790)

A feeding trial of 75 days was conducted in tanks to study the performance of shrimphead meal (SM), crab shell meal (CM) and silkworm pupae meal (SWP) on the growth anddigestive enzyme profile of pearlspot, Etroplus suratensis. Four iso-nitrogenous diets with31.5% crude protein replacing 50% fishmeal (FM) in the diets were formulated viz., SM (T1),CM (T2), SWP (T3) and a control (C). Pearlspot advanced fry, 2 cm in length and 1.1 g inweight, was stocked at 60 nos per tank. After 75 days of the experiment, feed conversionratio (FCR), feed efficiency ratio (FER) and protein efficiency ratio (PER) were observed to besignificantly better (p<0.05) in all treatment groups (T1, T2 and T3) than in control (C). T2 (CM)fed fishes exhibited a maximum specific growth rate (SGR) of 3.25±0.09, and significantlyhigher (p<0.05) weight gain (11.54±0.78 g) than T1, T3 and control. In enzyme assays, T2 (CM) fedfishes exhibited significantly higher (p<0.05) protease activity than other treatments.Lipase activity was significantly higher (p<0.05) in T3. However, there was no significantdifference with control diet-fed fishes. Significantly higher (p<0.05) activities of amylase,malate dehydrogenase (MDH) and lactase dehydrogenase (LDH) were observed in all thetreatments compared with control. The outcomes of the present study indicate that crabmeal (31.5% CP) could be effectively utilised as a 50% replacement for fishmeal in the dietof E. suratensis advanced fry for higher yields. Keywords:Crab meal, Enzyme activity, Growth, Shrimp meal,Silkworm pupae meal