Determining optimal salinity for embryonic, larval, and juvenile stages of golden rabbitfish ( S iganus guttatus ) using

Abstract

This study evaluated hatching rate, survival, osmolality, hematological and histopathological parameters to identify the optimal salinity of golden rabbitfish ( Siganus guttatus ) at three life stages: embryonic, pre‐feeding larvae, and juvenile. The study was conducted using a series of salinity treatments ranging from 10 to 40 ppt, assessing the hatching rate and egg osmolality during the embryonic stage, survival and plasma osmolality in pre‐feeding larvae, and survival, plasma osmolality, hematological parameters, and histopathological changes in juveniles over 14 days. The results showed that the highest hatching rate (73%) occurred at 20 ppt, with egg osmolality increasing with salinity, indicating an evolved osmoregulatory mechanism. At the pre‐feeding larval stage, survival was highest at 20 ppt (32%) and decreased with lower and higher salinities. Juvenile survival was high at all experimental salinities, although stress was evident at salinities exceeding 30 ppt, based on daily stress scores (body color and behavior) and histopathological observations. Histological analysis revealed minimum tissue damage in gills, liver, and kidneys at 30 ppt but higher abnormalities at higher and lower salinities. The findings suggest that maintaining salinity between 20 and 25 ppt optimizes hatching and survival rates during the early life stages, while salinity between 10 and 35 ppt is optimal for juvenile rearing. These results have implications for improving hatchery practices and juvenile rearing of golden rabbitfish.