EN
The relationship between the prevalence of normal serum agglutinins and precipitins to Aeromonas hydrophila and A. veronii biotype sobria in carp and the sensitivity of the fish to infection with these bacteria was studied. The presence of these antibodies depended on carp population and on individual fish. No correlation between the prevalence of agglutinins and the sensitivity of carp to infection was found. On the contrary, the fish having the precipitins to particular Aeromonas strains revealed significantly lower sensitivity to infections with the respective homologous strains than those without the precipitins.