Effect of salinity stress on cortisol hormone and glucose in grass carp fingerlings (Ctenopharyngodon idella)

This research was carried out over a period of 21 days in September - October 2009 in Shahid Maleki Warm Water Fish Culture Centre in Ahvaz. The aim of the present study was to evaluate cortisol hormone and glucose in response to salinity (1>, 3, 6, 9, 12 ppt) in grass carp, (Ctenopharyngodon idella) fingerlings. Fishes (weight 12.55±0.239 g and total length 10±0.069 cm) were placed in 250 l-tank (15 grass carps/ tank) for 21 days at 24.16±1.35°C. These treatments were tasted in three replicates. At the end of experimental period, blood was collected from the heart for determination of cortisol hormone and glucose. Results indicate that salinity up to 3ppt did not affect cortisol hormone and glucose in grass carp (p>0.05) but higher salinities (6 and 9ppt) adverse effects on cortisol hormone, glucose and survival (p<0.05). At 12ppt all fishes died prior to 14 days. Cortisol and glucose levels significantly increased with increasing salinity indicate that physiological response of fish to salinity stress.