Seasonal variation in diet composition of torpedo Trevally,Megalaspis cordyla (L) depending upon its size and sex

Samples of the torpedo trevally,megalaspis cordyla were randomly procured from commercial landings at karachi fish harbour from august 2013 to june 2014. the data of 293 (118 males and 175 females,?2 = 11.09,p<0.05) individuals were used to estimate size,sex and seasonal feeding preferences. the study revealed that m. cordyla categorically feeds on fish (40.62%),digested matter (27.81%),crustaceans (23.39%),mollusks (6.31%),polychaetes (1.11%) and coelenterates (0.76%). the index of relative importance (iri) and absolute index (ai) were applied to estimate main food item consumed by the fish. the males preferred acetes spp. and female mainly fishes. the feeding rate during post monsoon was relatively higher which was deduced from the number of full stomachs,whereas lower number of prey items was observed during post monsoon followed by pre monsoon. the stumpy feeding was observed during monsoon when most of the stomachs were empty. the gastrosomatic index estimates showed that females feed enormously in may followed by september,while in males high feeding rate was observed in april and june. present study document diet constituents of an important fish species captured in the northern arabian sea coast of pakistan as well as variation of feeding habits and intensity relative to size,sex and season. copyright 2015 zoological society of pakistan.