Phenoxy herbicides 2,4-D, its sodium and ethyl amine salts and ethyl esters, commonly used in aquatic weed eradication programmes, were tested by acute and static bioassay investigations on a cyprinid fishLebistes (Poecilia) reticulatus under laboratory conditions. The toxicities of these different formulations are compared and reported in relative toxicity ratings. ‘Safe application rate’ and ‘safe application factor’ equations were also calculated. Median lethal concentrations at various time intervals are also reported along with respective fiducial limits and regression equations. Comparative regressions are drawn for three time intervals, 24, 48 and 96 hr.