Abstract:
Chloramphenicol and oxytetracycline are used in ornamental fish culture to treat
bacterial infections. The present study was aimed at evaluating the effects of different
concentrations of chloramphenicol (2-10 mg L-1 for 10 days) and oxytetracycline (20 mg
L-1 for 3 and 10 days, 100 mg L-1 for 3 days) on hematological parameters and phagocytic
activity in the blood of koi carp, Cyprinus carpio. Results showed that treatment of
fish with 10 mg L-1 chloramphenicol for 10 days depressed haematocrit, erythrocyte
counts and mean corpuscular volume leading to anaemia. It also induced leucocytosis
coupled with neutrophilia, thrombocytosis and lymphocytosis. The phagocytic index
of the fish was also enhanced significantly with respect to the controls. The treatment
of fish with 100 mg L-1 oxytetracycline for 3 days induced leucopenia coupled with
neutropenia. Phagocytic index of these fish was significantly depressed compared to the
controls. Results revealed that precautions should be taken when high concentrations of
chloramphenicol or oxytetracycline are used in koi carp culture especially for long term
treatments.