Green Water Improves Growth and Clear Water Improves Swim Bladder Inflation Rates in Asian seabass, Lates calcarifer Larval Rearing System

Abstract

Asian seabass (Lates calcarifer) is suitable for industrial-scale development due to its high economic value worldwide. In Indonesia, hatchery juvenile production and aquaculture technology for Asian seabass are established; however, production often struggles to supply high-quality juveniles at the right size and time. Size variation due to uninflated swim bladders in larvae is a major factor causing slow growth in their cultivation. Two treatments, the green water system and clear water system (GWS and CWS), were tested to reduce size variation in the produced juveniles, with observed parameters including survival, growth rate, and enzyme activity. The results of a 20-day experiment showed that the juvenile mean standard length (8.85±0.54 mm) and body weight (14.0±5.0 mg) in GWS were higher, along with high gene expression of trypsin (>10-fold) and lipase (±10-fold). In contrast, CWS had a lower final mean standard length (7.98 ±0.62 mm) and body weight (10.0±3.0 mg), with low trypsin and lipase gene expression but high amylase gene expression (>20-fold). The swim bladder inflation rate was not significantly different between GWS and CWS (p>0.05). Endogenous probiotics are more noticeable and can support better growth and survival rates in the green water system by activating key enzymes such as trypsin and lipase. The green water system (GWS) provided a better substrate for the probiotic, which ultimately has a better effect on the development and growth of larvae by activating the main enzymes, such as trypsin and lipase.