Effect of sevimol on the moulting of the fresh water prawn, Macrobrachium kistnensis.

Short-term toxicity tests and median lethal concentrations of the prawn, Macrobrachium kistnensis , using sevimol were calculated. Exposure to 0.0005 ppm sevimol did not differ much in intermoult period from control prawns . In 0.0006, 0.0009 and 0.001 ppm of sevimol , the moulting frequency increased: in 0.001 ppm the duration decreased from 15 days at the beginning to 11 days at the third moult. The prawns in the proecdysial stage were more vulnerable to sevimol pollution than the other stage. Exuvia of prawns exposed to 0.0006 ppm were heavier than controls.