Feeding Ecology and Length-weight Relationship of Indian Glass Barb, Laubuka laubuca (Hamilton 1822) at Maguru Oya Stream (Deduru Oya River Tributary), Sri Lanka.

Abstract

Laubuka laubuca (Hamilton 1822) is a poorly studied freshwater fish found in South and Southeast Asia. This study was conducted to investigate the feeding habit and length-weight relationship of L. laubuca at Maguru Oya Stream, Sri Lanka. Gut contents of 180 fish were analysed, and food particles identified were categorised into 15 broad taxonomic groups. Relative abundance of each food category was calculated for 1-3, 3-5 and >5 cm length classes. Trophic niche breadth, food electivity index and Fulton’s condition factor of L. laubuca were calculated. Length-weight relationship was determined using the expression, W = aLb. Laubuka laubuca was a euryphagous-planktivorous fish and it showed a size dependent feeding pattern. Young fish had significantly broader (P<0.05) trophic niche breadth than that of adults. According to food electivity indices L. laubuca preferred euglenoids, rotifers, insect larvae, crustacean larvae, arachnid larvae and macrozoobenthos which were highly abundant in stream habitat. Laubuka laubuca showed a positive allometric growth pattern with length-weight relationship of log W = -2.3684 + 3.3528 log TL. Due to high availability of preferred food items in its habitat and positive allometiric growth L. laubuca could be categorised under least concern category in the IUCN Red List.