Abstract
In early 1990, about 80% surface area of Lake Kencil (4200 ha) was covered with water hyacinth. An experiment was conducted to identify the effectiveness of grass carp to control water hyacinth blooming in a tropical lake and related limnological changes. The fish was multiple-stocked up to 48,000 fingerlings during 1995-98. The limnological parameters were studied before, during and after the biomanipulation. Four years after the fish stocking, the water hyacinth was cleared and significant changes were observed for pH, water temperature, conductivity, BOD, COD, carbon dioxide, T-P, T-N/T-P, chl-a, NO3-N and NO2-N. Whereas DO, hardness, TN, NH4-N and total iron did not change.
