Formalin has been previously recommended to control monogeneans in fish culture recommended in marine waters the use of 740 mg l 1
formalin baths for up to 1 h to control protozoan and monogenean infestations and
suggested that the efficacy on fish was highly species specific This recommended
treatment regimen appears inappropriate for the bullseye puffer fish, as similar concentrations
in the toxicity tests resulted in lesions in skin and fins, and lethargy in the fish.