EVALUATION OF RESISTANCE TO Vibrio sp. BY Rachycentron canadum SUPPLEMENTED WITH PROBIOTIC BACTERIA

Rachycentron canadum fish has been arousing the interest of the aquaculture sector and is considered an emerging species for marine fish culture. There are few studies related to the development of probiotics that could help the resistance to pathogens related to this species. The aim of this work was to evaluate the resistance to Vibrio parahaemolyticus by R. canadum supplemented with bacteria that have probiotic potential. Eighty juvenile fish were used, divided into 16 boxes of 70 L, with aeration and biological filter. Four treatments, with 4 replications, were completely randomized: MG strain, B21C strain, commercial probiotic and control. The fish were fed twice a day with commercial food plus probiotic bacteria. Water monitoring was performed by measuring the parameters: pH, ammonia and V. parahaemolyticus (10⁶ cfu mL^-1) suspended in sterile saline. After 9 days, the fish were euthanized and evaluated for biometric parameters and presence of bacteria in the intestine. Data were submitted to analysis of variance and Tukey test (p> 0.05). The parameters pH and ammonia remained stable during the experiment with the means: pH 7.6 and 0.15 ppm ammonia. The bacteria used were able to colonize the fish intestines and significantly decreased the amount of Vibrio sp. in the intestines of fish. Fish weight supplemented with MG was significantly higher than control weight without bacteria, but did not differ from B21C treatment after 43 days. The survival rate of fish supplemented with MG was higher than that of commercial probiotic fed bacteria. It is concluded that the bacteria tested have potential to be used as probiotics in the supplementation of R.canadum fish.