SUBLETHAL TOXICITY TESTS OF MERCURY (Hg) TO NILEM FISH (Osteochilushasselti) GILLS TISSUE DAMAGE

Industry development in Indonesia resulted in sewage and polluting heavy metals such as mercury (Hg). These pollutants will be harm organisms that live at aquatic environment. Fish gills could be damage due to exposure by mercury. To know the influence of mercury's toxic against aquatic organisms by using toxicity test. An aquatic organism, which is usually used as toxicity test, is nilem fish (Osteochilushasselti). The objective of the study was to determine the value of LC50-96 hours in a toxicity test of nilem fish exposed to lead acetate; to determine the changes in the fish gill and to determine the concentration of lead mercury which causes tissue damage structure in the gills of nilem fish. The design used completely randomized design (CRD) with four concentrations (0; 0.08; 0.16 and 0.24 ppm) and three replications. The objective of the study was sublethal toxicity test. Lethal toxicity concentration data were descriptive and data from sublethal toxicity test were One Way. The analysis showed that there were highest edema 10% and 17% on day 4 and 12, the highest lamella fusion 35% and 59% on day 4 and 12, the highest hyperplasia 45% and 54% on day 4 and 12, and the highest necrosis the 65% and 80% on day 4 and 12. It was concluded that the value of LC50-96 hours in nilem fish (Osteochilushasselti) toxicity test was 0,3938 ppm; and damage of fish gill tissue changes started to occur in the lead mercury (Hg) concentration of 0,08 ppm.