In vivo treatment of the gill monogenean Pseudorhabdosynochus lantauensis (Monogenea, Diplectanidae) on orange-spotted grouper (Epinephelus coioides) cultured in the Philippines.

The gill monogenean Pseudorhabdosynochus lantauensis has been consistently observed on cultured orange spotted-grouper (Epinephelus coioides) fingerlings. The tolerance level of E. coioides to formalin (H2CO solution) and hydrogen peroxide (H2O2), two of the chemicals most commonly used to treat ectoparasites, was determined. The computed 3h and 6h LC10 of formalin were 322 mg L -1 and 275 -1 while the 9h LC10 and LC50 of H2O2 were 255 and 298 mg L -1 , respectively, at 28 o C. The efficacy of freshwater, hypersalinity, formalin and H2O2 bath treatment against P. lantauensis was determined in vivo. Hydrogen peroxide at 200 mg L -1 for 1h was effective in eliminating P. lantauensis on E. coioides