Studies on Digestive Enzymes in Different Size Groups of Channa aurantimaculata Musikasinthorn, 2000

Abstract

Amylase, cellulase, trypsin, chymotrypsin, lipase and total protease are primary digestive enzymes in the fish study. Channa aurantimaculata (Musikasinthorn, 2000) is an omnivore fish species, specifically found in Brahmaputra River of Assam, India. Due to its attractive physical features, this fish is favored as food and is used as an aquarium fish as well. This study aimed to observe digestive enzyme (amylase, cellulase, trypsin, chymotrypsin, lipase, and total protease) activities from the gastrointestinal tract (GI tract) in different size groups (adult, juvenile, and fry) of C. aurantimaculata using quantitative enzyme assay. After collection, some of the adult fishes were cultured and fed with small live fishes, whereas others were freshly dissected to conduct experiments. In the fry age group, α amylase activity was the highest (1±0.31 unit·mg protein-1) and in the juvenile group, protease activity was found the highest (4.6±3.1 unit·mg protein-1). In adults, total protease, trypsin, chymotrypsin, and lipase activities were significantly higher (p<0.05) than juvenile and fry age groups. A comparative study was conducted on the total protease activity between wild and cultured fish species in adult, juvenile, and fry age groups. A significant difference (p<0.05) was only detected in the adult age group of wild and cultured species. The present study concluded that the protease enzyme is the primary digestive enzyme (0.9±0.39-17.01±8 unit·mg protein-1) found in C. aurantimaculata, which supports the carnivorous type of food habit with relative gut length less than one (0.45-0.59) in different age groups.