DIGESTIVE ENZYME ACTIVITY OF PROTEASE, α-AMYLASE, AND LIPASE OF RABBITFISH (Siganus guttatus) LARVAE

Abstract

One of the main constraints in seed production of rabbitfish is the high mortality during larval stage. Lack of suitable size of <150 mikron of live feed become the main issue in hatchery because rabbitfish require very small feed, also rabbitfish larvae have low capacity to digest the feed. The aim of this study was to determine the activity of digestive enzyme including protease, α-amylase, and lipase in rabbitfish larvae, as a basic for feed management. Rabbitfish larvae were reared in two fiber glass tank filled with 700 L of sewater (30-31 ppt salinity) and equipped with aeration. Test fish were newly hatched rabbitfish larvae which were stocked at density of 50 fish/L. Live feeds used were rotifers and Artemia nauplii. Measurement of the digestive enzymes activity was conducted when the larvae age at 2, 5, 10, 15, 20, 25, 30, and 35 days after heatching (DAH). The results showed that the highest enzyme activity during endogenous phase was the protease of 0.0442 U/mL/minute and the lowest was the α-amylase of 0.021 U/mL/minute. During exogenous phase, the peak enzyme activity of protease occurred at 25 DAH, for the amylase occured in 15 DAH and for lipase 25 DAH. The enzyme activity was associated with age of the rabbitfish larvae and related to the phase where larvae need to obtain life feed.