ABSTRACT
The goal of water quality management is to regulate the physical, chemical and biological environment of the culture system so that conditions favour the optimum growth of the fish crop. Changes in water quality occurring during fish culture directly or indirectly are the result of the feeds added to the pond to increase fish growth. Some water quality parameters are largely unaffected by the addition of the fish feeds. Concentration of total alkalinity, hardness, and chloride are initially dictated by the quality of the water supplying the pond. Oxygen consumption rates by fish vary with dissolved oxygen concentration, feeding status, weight of fish, and water temperature. Food conversion values are higher for fish in ponds with chronically dissolved oxygen concentrations than in ponds with higher dissolved oxygen concentrations. Phytoplankton die-offs can cause severe depression of dissolved oxygen concentration. Dissolved oxygen concentrations will decline drastically, and they may fall low enough to cause fish kills.
