Effects of salinity level on the survival, growth, feed utilization, carcass composition, haematological and serum biochemical changes of juvenile Meagre (Argyrosomus regius) (Asso, 1801) grown in ground saltwater

A study was performed to examine the effects of salinity on water quality, fish performance, carcass composition and haemato-biochemical parameters in juvenile meagre, Argyrosomus regius. Fish (5.0 g) were stocked in fibreglass tanks at four salinity levels: 8 parts per thousand, 16 parts per thousand, 24 parts per thousand and 32 parts per thousand, and fed a pelleted diet (47/17 protein/lipid) for 56 days. Results indicated that the growth, feed utilization, carcass composition and haemato-biochemical parameters of meagre gradually improved with the increase in salinity up to 24 parts per thousand and then significantly (p <= .05) decreased at 32 parts per thousand. The survival per cent showed a significant decrease when A. regius exposed to 8 parts per thousand salinity. An improvement with 32%, 47% and 34.1% of FCR, protein productive value and energy utilization was detected at 24 parts per thousand compared with 8 parts per thousand salinity respectively. The highest content of protein and the lowest of lipids were recorded in fish carcass at 24 parts per thousand compared with the opposite trend at 8 parts per thousand salinity. The 24 parts per thousand salinity treatment exhibited the highest value of haemoglobin (4.9 g/dl) and the lowest ratio (0.73) of albumin/globulin. The serum total protein, albumin and globulin were significantly higher at 24 parts per thousand and 32 parts per thousand salinity than those at 8 parts per thousand and 16 parts per thousand salinity groups. These findings indicate that 24 parts per thousand salinity level might be the best for meagre.