The Effect of Salinity Stress on Choloride Cell and Gill Histopathology of Common Carp (Cyprinus carpio) Fed with Oral Cortisol v

Cortisol is a corticosteroid hormone that plays important roles in various aspects of fish physiology including ion regulate, growth, stress and immune functions.the highest abundance of corticosteroid receptors in the gill, intestine and kidney that their abundance change influenced by salinity frequently. In this study, the effect of dietary cortisol on gill tissue of common carp (Cyprinus carpio) fingerling affected by salinity stress wasinvestigated. Common carp (1.36 ± 0.12 g) was distributed in 4 treatments in 3 replicates and fed with commercial food containing 0 (control), 50, 100 and 200mg kg-1 hydrocortisone for 8 weeks. Then resistance to salinity with in 7 days in 12 ppt salinity and gill tissue was investigated. In investigation of gill tissue, the amount of damage were controlled (hyperplasia, hypertrophy, hyperemia and edema) at cortisol treatement. Fishes fed cortisol shown a minimal damage among treatements (P< 0.05) and increased number of choloride cells with salinity stress. This observation state that this treatement of fish have better osmoregulation during salt stress.