Nursing and Feeding of Asian Seabass ( Lates calcarifer ) for Freshwater Aquaculture Systems

Asian seabass ( Lates calcarifer ) is a commercially important euryhaline species capable of tolerating a wide range of salinities. It is widely cultured in coastal and brackish‐water environments; however, information on its adaptation and performance under freshwater conditions remains limited. Therefore, the present study investigated the potential of integrating Asian seabass into freshwater aquaculture systems through gradual salinity acclimation and subsequent feeding evaluation. Fry with an initial body weight of 0.45 ± 0.21 g (mean ± standard deviation [SD]) were reared at a salinity of 10 ppt for 90 days and then gradually acclimated to freshwater by reducing the salinity from 10 to 0 ppt over a 30‐day period. A feeding trial using commercial feed, trash fish and live fish was conducted to evaluate growth and health responses in freshwater‐adapted fingerlings under controlled conditions. During saline rearing, fry growth peaked at 6 g with 60% survival. With decreasing salinity (10–7–4–0 ppt), fish weight increased to 8 g with 82% survival at 0 ppt, accompanied by increased haemoglobin levels and decreased blood glucose levels. Chloride cell density decreased progressively with declining salinity. In the freshwater feeding trial, fish fed live fish showed superior growth and specific growth rate with zero mortality, followed by commercial feed and trash fish, whereas trash fish treatment showed the highest mortality (20%). No significant differences in haemoglobin and blood glucose levels were observed among feed treatments, although goblet cell density was highest in fish fed live feed. Overall, the study provides preliminary evidence that Asian seabass can be successfully acclimated to freshwater and maintained under different feeding strategies with acceptable growth and survival.