Ichthyophthirius and Aquaculture in the People’s Republic of China     Lin Tianlong, Yang Jinxian, Liu Xiaudong, Gonghui Chenqiang, and Xu Binfu   Fish Disease Control Center, Animal Husbandry and Veterinary Medicine Institute, Fujian Academy of Agricultural Sciences, Fuzhou, China     Chinese aquaculture has developed rapidly since 1978 with an average annual growth rate of 7%. In the year 2000 aquaculture production reached about 20 million tons per year, and China now has one of the largest aquaculture industries in the world.  Ichthyophthirius is a major threat to cultured freshwater fishes. More than 28 cultured fish species in China can become infected with I. multifiliis, and heavy losses have been reported over the past decade. Based on our research with cultured eel (Anguilla anguilla), Ichthyophthirius is the most common and virulent pathogen of this species.  Parasites found on infected eels have different tolerances to heat with some isolates surviving at temperatures as high as 28oC.  Based on variation of surface immobilization antigens, four different serotypes of I. multifiliis were found in eight parasite strains isolated from cultured eels.  Our findings suggest that differences in serotype correlate to variations in temperature tolerance.  A recipe containing ginger, capsicum, pepper and borneol has been used effectively to treat Ichthyophthirius-infected eels in densely stocked concrete ponds.