Diet-Influenced Performance of Juvenile Common Carp (Cyprinus carpio L.) after Experimental Aeromonas Infection

Abstract

The effects of two diets, SGP 493 (Aller Aqua, Denmark; SGP) and chironomid larvae (Katrinex, Poland; CHI), on juvenile carp survival and hematological values after subcutaneous infection with Aeromonas veronii bt. sobria (strain K144) were studied. All infected fish developed skin ulcers and both groups developed anemia, i.e., a severe reduction in hemoglobin content with- out a decrease in red blood cell count and a minor decrease in hematocrit. There were higher levels of hematocrit, hemoglobin, and mean cell hemoglobin in the CHI group at the beginning of the infection, together with a slightly higher erythropoietic potential. At the end of the experi- ment, partial recovery of hemoglobin levels took place. The SGP diet induced considerable leukocytosis in healthy fish, which did not enhance their resistance to the infection. Leukopenia, lymphopenia, and reduced phagocyte activity took place in all infected fish. Survival 15 days after injection was 50% in SGP and 63% in CHI, suggesting that fish fed natural food were slight- ly less susceptible to Aeromonas-induced anemia even though feeding natural food or SGP did not significantly affect the performance of infected fish.