Acute Toxicity of Sodium Nitrite on Channa punctatus (BLOCH) and Mystus (Mystus) vittatus (BLOCH)

This paper deals with the toxicity of sodium nitrite to freshwater fishes, Channa punctatus (BL.) and Mystus (M). vittatus (Bl.) as to determine the acute toxicity. The LC 50 values were obtained by using a static bioassay method for a period of 24, 48, 72 and 96 hour intervals. The LC 50 values of sodium nitrite for C. punctatus were 375, 325, 250 and 200 ppm and for M. (M). vittatus 164, 140, 90 and 64 ppm, respectively. A profuse mucus secretion was evident at higher concentrations as compared to lower ones. The probable causes of mortality of the fishes are also discussed.