Secondary Stress Response of Nile Tilapia, Oreochromis niloticus, After Direct Transfer to Different Salinities

The secondary stress response of Nile tilapia, Oreochromis niloticus after direct transfer to saline water was evaluated assessing the levels of hematocrit, plasma glucose, sodium, potassium, chloride and calcium. Fish were transferred directly from freshwater to two experimental salinity (9 and 18 ppt) for 72 hours. Plasma glucose, Na + , K + , Cl - ++ all increased however, hematocrit did not change throughout the 3 days exposure period. Considering the parameters measured in this study Nile tilapia appeared to exhibit a stress response to direct transfer to saline water, nevertheless, the magnitude of stress response was related to salinity level.