Triclosan is an antibacterial ingredient that can be found in medical, household, and personal care products. Triclosan, a chlorinated phenolic chemical, ensures its presence in soil, surface water, drinking water, and other environments due to its extensive use and high persistence potential. Acute toxicity studies were performed on the fish Heteropneustes fossilis to determine the LC50 value of triclosan (5-chloro–2-(2,4dichlorophenoxy) phenol) over the periods of 24, 48, 72, and 96 hours, as well as to identify behavioural changes. Using Finney's probit analysis
The LC50 values were discovered after analysis, and they were 9.54, 8.2, 7.59, and 7.14 mg/L for 24, 48, 72, and 96 hours, respectively. The fishes displayed erratic movement, increased surfacing activity, haemorrhagic eyes, reddish fins, decreased operculum motions, body tremors, increased mucous deposition all over the body, and a loss of equilibrium. These toxicity test findings revealed that triclosan is harmful to Heteropneustes fossilis.