Investigation of development laws of grouper Cryptocaryon irritans on Hainan island

In this paper，fixed point，sampling detection and key regional focus detection method were adopted to investigate Cryptocaryon irritans disease incidence and epidemic regularity on the main grouper culture zones of Hainan island from 2014 to 2015. The results showed that，overall risk of nearly two years grouper C. irritans trypanosomiasis slightly reduced；Epinephelus malabaricus，E. coioides and Plectropomus leopardus were most likely to outbreak C.irritans disease. C. irritans disease mainly concentrated in the eastern coastal areas，such as Wenchang to Wanning. The outbreak of the disease had close ties to the water temperature for pond aquaculture belt grouper，inclined belt grouper and cement pond aquaculture leopard gills spines perch came on all the year round，but when the water temperature was less than 25℃ as the turn of the spring and summer or the turn of autumn and winter every year，Wenchang to Wanning coastal area had a lot of disease，in QiongHai Oucun，Wanning port，there was large outbreak and death in the pond.