p. 243 - 250 BACTERIOSES DE LA TRUITE ARC-EN-CIEL (Salmo gairdneri irideus) ELEVEE EN EAU DE MER Elena Dumitrescu et Irina Voicu Institut Roumain de Recherches Marines Constanta Abstract The paper presents the most important infectious diseases of the rainbow trout(Salmo gairdneri irideus) occured during its experimental cultivation in Black Sea water. The bacteria involved in infectious processes were Aeromonas hydrophila, Vibrio parahaemolyticus and Vibrio anguillarum, identified according to specific biochemical tests. Sensibility of subjects as well as propagation of infectious was more pronunced during summer, when stressing conditions are also more pronounced, directly related to higher temperatures, scarce oxygen conditions; presence of ammonia and suspended organic matter. Prognisis of the disease was always negative, final stage of the case history being septichaemia. Preventive treatment with antibiotics applied monthly during the summer, reduced mortality by 50%.