Diet Overlap between Introduced Catla catla, Labeo rohita and the Native Dawkinsia filamentosa in Vellayani Freshwater Lake, Kerala Southwest Coast of India

The present study was undertaken to document the gut contents of the exotic species, Catla catla and Labeo rohita and the main indigenous fish Dwakinsia filamentosa in Vellayani Fresh water Lake at Thiruvananthapuram, so as to ascertain the possibility of dietary overlap between the indigenous and exotic fishes due to the introduction of non native fishes for enhancing fish stock has been going on in the lake from 2010 onwards. The study was carried out from August 2013 to July 2014. Gut content analysis was done by Points method (Hyslop, 1980). The extent of diet overlapping was assessed using Percentage of diet overlap. For D. filamentosa, the cyanophytes were the major component (43.82 %), followed by chlorophytes (26.88 %) and chrysophytes (19.76 %). The major food items of C. catla and L. rohita were also cyanophytes, chlorophytes and chrysophytes. Percentage of diet overlap was found to be 60 % showing that dietary overlapping is significant, and in the long run, this may lead to negative impacts on the breeding and reproduction of the native species.