Water quality-disease relationship on commercial fish farms

Abstract

There are significant interrelationships between host organisms, their pathogens, and environmental factors (water quality). Adverse environmental conditions may decrease the ability of organisms to maintain an effective immunological response system, so that an increased susceptibility to various diseases might be expected to occur. This certainly occurs in aquatic organisms, particularly fish, in which acute and/or chronic pollution of surface waters can cause a reduction in the level of unspecific immunity to disease. This chapter focuses on the fundamental indicators in aquatic environments important in commercial fish farming, including water temperature, pH, oxygen, ammonia, nitrates and nitrites, and chlorine. It lists the effects of changes in these indicators on the fish and how they relate to possible diseases. An important part describes prevention of fish damage due to changes in water quality.