Digestive Enzyme Activities During Larval Development of Striped Catfi sh, Pangasianodon hypophthalmus (Sauvage, 1878)

Abstract

The specific activities of digestive enzymes of striped catfish, Pangasianodon hypophthalmus (Sauvage, 1878) larvae were examined from hatching to 21 days after hatching (DAH) using biochemical techniques. Fertilized eggs of striped catfish hatched after 24 hr and the larval yolk sac was totally absorbed by 3 DAH and then the larvae were provided with artemia throughout the experimental period. The mouth and digestive duct appeared 1 DAH and reached a morphological similarity to the adult 15 DAH. The specific activities of acid and alkaline protease were detected at hatching and 3 DAH, respectively. The specific activities of amylase and lipase were detected 1 DAH and at hatching, respectively. The specific activities of all studied enzymes showed the similar pattern of fluctuation during the first two weeks, and then increased until 21 DAH. These results demonstrated the presence of acid and alkaline proteases, amylase and lipase at a very early life stage, and showed an adaptation period of 2 wk to the first feeding. The existence of these enzymes means that striped catfish larvae have an endogenous ability to digest proteins, carbohydrates and lipids that increases with age. This information can lead to the possibility of developing a cost-effective formulated feed for intensive farming of this fish.