The work presented here represents an 18-month study to examine the relationship between environmental conditions, bacterial load in the water and bacteria levels in tissue macrophages of a range of clinically healthy freshwater fish species, farmed in a range of culture systems in Thailand and Vietnam. Preliminary assessment was made of the clinical significance of the macrophage bacterial load. The aim of this work was to improve production in fresh-water aquaculture through the control of clinical bacterial disease and subclinical infection, and to identify management practices most effective in promoting fish health. The sites chosen in Thailand were all catfish farms to allow comparison between the same fish species cultured in different farming systems. A greater choice of farming systems and cultured species were available around CanTho, Vietnam, compared with Bangkok and a range of freshwater fish species, farmed in a variety of culture systems was, therefore examined in Vietnam.
This report describes the purpose of this study, the work carried out and the results obtained. An executive summary is provided at the end.
