Investigating the potential of protexin probiotic in improving the resistance of Sobaity Seabream Sparidentex hasta to temperature and salinity stresses

In order to investigate the effect of protexin probiotic on resistance of Sobaity seabream Sparidentex hasta to temperature and salinity stresses, an experiment was carried out with 240 pieces of fish fingerling with average initial weight of 2.99±0.87 g for 10 weeks. Experimental treatments were consisted of four levels of 0, 0.5, 1 and 2 g protexin per kg of diet, each with three replicates in a completely randomized design. During the experimental period, feeding was performed by hand on a daily basis based on full sanitation at three intervals. At the end of the experimental period, the fish were exposed to two temperatures of 15 and 37°C for 30 minutes in thermal stress test and to two salinity levels of 12 and 70 ppt for one hour in salinity stress test. The results showed that in 1 and 2 g protexin treatments, the survival rate in high temperature, low temperature and high salinity stresses increased significantly compared to the control group (P0.05). Among the different levels of protexin used, the most effective dose on survival rate in temperature and salinity stresses in Sobaity seabream fingerling was the level of 2 g protexin per kg of diet. The results of the present research revealed that the dietary supplementation of protexin probiotic could favorably affect the survival rate in high temperature and salinity stresses in Sobaity fingerling.