Relationship between Body Shape and Food Habits of Fish from Three Reservoirs of Sri Lanka

Abstract

In the present paper, an attempt is made to investigate whether the body shape indices can be used to predict food habits of fish species in three reservoir fish communities of Sri Lanka. The present analysis is based on the studies on food and feeding habits of fish species and their body shape indices in three Sri Lankan reservoirs, namely Minneriya, Udawalawe and Victoria. Body proportions of individual fish species were determined as P1 (= Maximum height of the body/ Maximum width of the body) and P2 (= Total length/ Maximum height of the body), which were found to be negative curvilinearly related. Trophic indices (Ti) of individual fish species were determined on the basis of trophic level of each food item and the fractions of all food items consumed by fish species, which ranged from 1 for exclusively herbivorous species to 3 for carnivorous species. A negative logarithmic relationship between P1 and Ti indicates that laterally compressed fish species with deep bodies feed on lower trophic levels in the food web. On the other hand, dorso-ventrally flattened species with low P1 have higher trophic indices than those with high P1. The positive logarithmic relationship between P2 and Ti also indicates that short, deep-bodied fish species representing low P2 values feed on lower trophic levels whereas slender, long-bodied species with high P2 values feed on higher trophic levels. The body shapes, measured as simple body proportions of the definitions of P1 and P2, can therefore be used to predict feeding habits of fish.