The effect of reduced salinity on growth,food conversion and protein efficiency ratio in juvenile spotted grunter, Pomadasys commersonnii (Lacépède) (Teleostei: Haemulidae)

Salinity has been proven to have a significant effect on the growth and survival of anadromous fish species; however, there is a paucity of information regarding its effect on euryhaline marine species. Experiments were conducted to examine the effect of hyposalinity on the osmoregulation and growth of juvenile spotted grunter, Pomadasys commersonnii (Lacépède). Although the spotted grunter is considered to be a strong osmoregulator, growth performance and survival was compromised below isosmotic concentrations. The growth rate, condition and food conversion of fish in low salinity (5‰) were lower than in either isosmotic (12‰) or hyperosmotic (25‰ and 35‰) conditions. Mortality was also significantly higher at 5‰. From these results, it is concluded that P. commersonnii can be successfully cultured in salinities ranging from 12‰ to full-strength sea water (35‰).