Abstract
A massive fish die-off was reported in Kandy Lake, Sri Lanka, in 2009. The maximum number of dead fish was as high as 150 per day. A survey of the water quality of Kandy Lake was conducted in the afternoon on 28 March for the daytime survey and before dawn on 29 March 2010 for the nighttime one. In this research, a hydrographic survey and water sampling at various depths were carried out to determine the cause of the fish die-off. Dissolved Oxygen (DO), nutrients, and heavy metals that could cause a fish die-off were thoroughly analyzed. The lake had sufficient DO to support a fish habitat near the surface layer even in the nighttime. The lake water had high T-N and low T-P concentrations, which could limit the growth of phytoplankton, such as Microcystis. No significant lethality was attributed to heavy metals. No conclusive evidence of the cause of the fish die-off was obtained during the investigation period; however, occasional disturbances could inversely affect a fish habitat. Long-term monitoring of the water quality of Kandy Lake seems to be required.
