Ecology, Environment and Conservation Paper

ANALYSIS OF EXTERNAL MORPHOLOGY OF DIGESTIVE SYSTEM AND DIGESTIVE ENZYME ACTIVITY OF TWO EDIBLE NATIVE FISH SPECIES; ANABAS TESTUDINEUS AND ETROPLUS SURATENSIS

Dafina Wilfred and Sofia Xavier

Abstract

External morphological features of fish digestive system and digestive enzyme activity is found to be closely linked to its pattern of food and feeding. The present study was done to understand the digestive physiology of two species of edible freshwater fishes; Anabas tesudineus and Etroplus suratensis. External morphology of the digestive system and the activity of the amylase, protease and lipase in the liver, stomach and intestine of these fishes were analysed for the study. Intestine of Anabas testudineus had a reduced and straight pattern characteristically seen in carnivorous fishes. The significantly increased level of protease activity in the stomach and intestine of Anabas testudineus also indicated its inclination towards carnivory. Intestine of Etroplus suratensis is long and coiled as seen in herbivorous fishes. The significant increase in liver amylase activity of Etroplus suratensis also supported its preference for herbivorous diet. The considerable digestive enzyme activity levels along the digestive tract of these fishes suggested its omnivorous pattern of feeding. The present study thus indicated the close relation between the digestive physiology and the pattern of feeding in fishes, which could be utilised for selecting better feeding options to ensure optimal growth of these native fishes during aquaculture practices.