Acute toxicity, behavioral and nitrogen metabolism changes of sodium cyanide affected on tissues of Tilapia mossambica (Perters).

The toxicity of sodium cyanide to the freshwater fish, Tilapia mossambica, was studied using the static bioassay method. The LC(50) value at 96 hours was found to be 44.33 µg/L (normal concentration is 25 µg/L). Behavioral changes, when exposed to a lethal concentration of sodium cyanide, showed increased opercular movement, increased surface behavior, loss of equilibrium, change in body color, increased secretion of mucus, irregular swimming activity, rapid jerk movement, "S" jerk, partial jerk, and aggressiveness. A decrease in ammonia level of gill (67.56%), muscle (63.88%), and liver (53.29%) with increased levels in urea gill (75.83%), muscle (63.53%), and liver (107.49%) was observed in a lethal concentration of sodium cyanide at the end of day 4 of exposure. In a sublethal concentration (4.43 μg/L), a decreasing trend in ammonia level continued up to day 15. Urea level at days 1 and 5 decreased on days 1 and 5, but increased on days 10 and 15.