LC(50) DETERMINATION FOR MALACHITE GREEN AND FORMALIN ON RAINBOW-TROUT (ONCORHYNCHUS-MYKISS) JUVENILES

Two relatively inexpensive and generally available prophylactic and th erapeutic agents, commonly used against a wide spectrum of fish diseas es by fish farmers throughout the world, namely zinc - free malachite green and formalin were investigated. The specific aim was the determi nation of the 96 h LC50 values for rainbow trout juveniles. These LC50 values are useful measurements of relative acute lethal toxicity to t est organisms under specified conditions. From the results obtained du ring these experiments, it is recommended that O. mykiss juveniles can be bathed in malachite green concentrations of 1.25 x 10(-4) g-l-1 to 2.25 x 10(-4) g-l-1 or formalin concentrations of 0.0625 ml-l-1 to 0. 1 ml-l-1 for as long as 24 h without mortalities.