INVESTIGATING THE ROLE OF HEAT SHOCK PROTEINS AND MELANOPHORES DURING STRESS CAUSED BY HIGH LIGHT INTENSITY IN INDIAN MAJOR CARP, CATLA CATLA

In response to several stressors such as intense light, fish elicit a generalized physiological stress response. Catla catla (61.3 ± 2.1 g) were exposed to five different light intensities of 983 ± 162 lx (L1), 1828 ± 324 lx (L2), 2676 ± 409 lx (L3), 3442 ± 648 lx (L4) and 114 ± 4 lx (Lc, control). Higher light intensities resulted in physiological stress, significantly (P<0.05) higher levels of heat shock protein-70 and heat shock protein-90 were found in both hepatopancreas and muscles of fish exposed at L4 treatment compared to the others to cope up with the stressor. A direct relationship was found between the light intensity and the serum glucose level. Significantly (P<0.05) higher glucose level was found in L4 exposed fish compared to the others. Fish at L4 had aggregated its pigments in the melanophores (punctate stage) to reflect intense light. This study could be useful in understanding the aspects of stress induced changes in fish skin melanophores. As a consequence of stress due to intense light, a 12.5% of growth retardation was found in L4 treated fish. Significantly (P<0.05) lower feed conversion ratio was found in Lc than the other treatments. Hence, the present investigation is aimed to evaluate the acute and sublethal effects of light intensities in catla.