Diseases resistance, of Nile tilapia (Oreochromis niloticus), blue tilapia (Oreochromis aureus) and their hybrid (female Nile tilapia x male blue tilapia) to Aeromonas sobria

The resistance to disease caused by the Aeromonas sobria in three genotypes of tilapia, Nile tilapia (Oreochromis niloticus), blue tilapia (Oreochromis aureus) and their hybrid (female Nile tilapia x male blue tilapia) was studied. Based on comparison of median lethal dose (LD50), functions of nonspecific immunity, including total amount of complements, bactericidal reaction by alternative pathway of complement (C-3 shunt), percentage of erythrocyte C-3b receptor aggregates, leukocyte phagocytic function, as well as erythrocyte active rosette of T lymphocyte, it is indicated that the hybrid has the highest resistance to the disease caused by A. sobria, while blue tilapia has the lowest resistance. (C) 2004 Elsevier Science B.V. All rights reserved.