Effects of waterborne chloramphenicol and oxytetracyclene exposure on haematological parameters and phagocytic activity in the blood of Koi carp, Cyprinus carpio

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.