Comparative examination of susceptibility of two genotypes of carp ( Cyprinus carpio L.) to infection with Aeromonas salmonicida

Progeny of a Hungarian breed as well as its F1 cross with the Japanese coloured carp were grown in ponds for 3 months. After artificial infection with Aeromonas salmonicida, susceptibility of the fish to carp erythrodermatitis was evaluated. Growth and condition factor of the hybrid carp were significantly higher than those of the homozygous group. Following the infection with Aeromonas salmonicida, morbidity of the hybrid was half that of the homozygous fish. The relative mass of spleen, kidney and head kidney of the fish having no clinical sign of infection was significantly higher than in the specimens with inflammatory or ulcerous local reactions. Non-susceptibility is presumably correlated with relatively extensive leucocyte propagation in the lymphoid tissues.