Abstract: Efficacy of nitazoxanide(NTZ)by oral administration to Pseudosciaena crocea for the Cryptocaryon irritans infection was studied.NTZ was first-dissolved in dimethyl sulfoxide to be sprayed evenly on an extruded fish meal,which was,then,coated with a thin oil film.The meal was fed to the fish every day at the rates of 50,100 or 150mg per kg of the fish body weight.The treatments lasted 6days.At the same time,simultaneously hatched theronts were introduced to infect the fish at a rate of 10 000 per P.crocea.Subsequently,the numbers of trophonts appeared on the gill,skin and fins of each fish were monitored regularly.After the 6-day treatments,all P.crocea were infected with thetheronts in large numbers,and the fish fed with 150mg·kg-1 diet died,while the others survived.The oral NTZ treatment apparently did not prevent P.croceafrom being infected by C.irritans.