Estimation of acute toxicity of ammonium sulphate to the fresh water catfish, Heteropneustes fossilis I. Analysis of LC50 values determined by various methods.

The acute toxic effects of ammonium sulphate to fresh-water catfish, Heteropneustes fossilis (H. fossilis) have been studied by determining LC50 values with 95% confidence limits, by the graphic method, the logistic method, the Spearman and Karber method and the trimmed Spearman-Karber method. The trimmed Spearman-Karber method was found the most ideal for ammonium salt toxicity test. The flaws in the trimmed Spearman-Karber method are also discussed.