Although formalin has been widely recommended as therapeutic for the control of parasite
epizootics,thisdoesnotnecessarilyapplytoallculturedspecies.Forinstance,Digglesetal.
in experiments with bream (Acanthopagrus australis) infected with the monogenea Polylabroidesmultispinosusfoundthat148mgl 1 formalinfor30minat20jCwaseffectiveinremoving
thisparasitefromgillsofjuvenileandadultfish;however,thetreatmentappearedtobestressfulto
the bream. Furthermore, formalin (111 mg l 1) significantly reduced 48% of the monogenea
Haliotrema johni and 78% of Haliotrema sp. populations in the treatment of cultured golden
snapper,Lutjanusjohni,althoughfishduringthe30-minexposureexhibitedsignsofstress