Study of bacterial loading in macrophage cells of hybrid catfish

Abstract

Hybrid catfish (Clarias macrocephalus x Clarias gariepinus) farming has developed very successfully in Thailand over the last 10 years. Farmers, however, are still encountering disease problems and, as a result, face economic losses. Some disease problems are associated with inadequate farm management practices. This study was carried out to investigate the presence of bacteria in macrophage cells isolated from hybrid catfish cultured in different environmental conditions. Results from farm investigations showed that the percentage of macrophages containing intracellular bacteria was related to water quality parameters. Experimental trials were conducted using high stocking density as stressor and bath challenge with pathogenic Aeromonas hydrophila. The results showed that fish kept in high density and bath challenged with bacteria had higher percentage of macrophages containing bacteria than those kept under normal conditions. The presence of bacterial loading in macrophage cells is, therefore, considered to be an indication of the health of the fish.