Juvenile hybrid grouper (Epinephelus coioides x E-lanceolatus) are euryhaline and can grow in a wide range of salinities

摘要

This study was carried out to find the optimal salinity for growth of juvenile hybrid grouper (Epinephelus coioides x E. lanceolatus). Hybrid groupers (23.5 +/- A 1.1 g initial weight and 11.37 +/- A 0.18 cm initial length) were reared at four salinities (10, 15, 20 and 30 ppt) (in triplicates with 15 fish per replication) for 3 months. Feed intake, growth, feed conversion, visceral organ indices, chemical composition and digestive enzyme activities were examined and used as assessment criteria. Growth, feed conversion and visceral organ indices were similar across the four treatments, and there were only minor differences in the proximal compositions (moisture, protein, lipid and ash) of muscle and carcass. The specific activities of trypsin, amylase and the ratio of amylase to trypsin activities suggested a possible adaptation of digestion of protein and carbohydrate in relation to salinity. The findings indicate that the hybrid grouper is euryhaline and is capable of growth over a wide salinity range (10-30 ppt). This may facilitate culture of the fish in both brackish water and seawater.