GROWTH RESPONCES OF MAJOR CARPS REARED UNDER CHRONIC STRESS OF CHROMIUM

For the determination of growth responses of major carps viz. Theila, Gibelion catla, Rohu, Labeo rohita and Mrigal, Cirrhinus mrigala when exposed with chronic stress of chromium in the laboratory. The fish used in this study were 240-day age group. The growth performance viz. wet weight increase, fork and total length increase, feed intake, feed conversion efficiency and length-weight relationship were determined. The fish were fed with feed containing a diet 30% DP and 3.14 Kcal/g DE up to satiation daily. At the end of present research trial, the fish were dissected and its vital organs (bones, gills, gut, intestine, kidney, liver, scales, skin, muscle and fats) were isolated for the determination of chromium contents in fish body. During growth trials under Cr sub-lethal stress, L. rohita gained significantly higher weight of 13.42±0.60 g, followed by that of C. mrigala (12.23±0.49) and G. catla (10.66±0.38 g). All the three control (un-stressed) fish species showed significantly better growth responses due to higher feed consumption than those grown with sub-lethal chromium exposure. The exposure of chromium during 12-week growth trials to fish instigated significantly variable chromium accumulation in the body organs of these major carps. However, maximum accumulation was observed in fish liver followed by kidney and gills.