Seasonal changes in biochemical composition of the Lethrinus lentjan were studied for a period of one year from February 2010 to January 2011 in the fishing area (Chinnamuttom harbour– Southern tip of Kanyakumari). The amounts of carbohydrate, lipid and protein were determined in muscles, liver, gills and kidney. The results were expressed as mg/gm. The concentration of carbohydrates fluctuated from 1.12 to 1.75, 2.12 to 2.73, 0.72 to 1.99 and 0.32 to 0.68, protein content varied from 18.75 to 23.84, 17.18 to 18.73, 14.35 to 15.42 and 15.32 to 16.89 and the lipid content ranged from 7.28 to 9.88, 6.18 to 9.92, 7.75 to 8.95 and 7.05 to 8.45mg/gm respectively (muscles, liver, gills and kidney). Protein content was high during spawning season and low during the post-spawning season. Lipid content estimated was also low during the spawning season and high during pre-spawning season in all the four selected tissues. This indicated that a significant inverse relationship between protein and lipid in muscles, liver, gills and kidney (r = - 0.45, -0.114, -0.099 and -0.37 respectively).
