This paper deals with a study on the white speckle disease of garrupa, Epinephe-lus akaara (Temminek et Schlegal). Results are as follows: 1. Pathogen: Petalosoma epinephelis Huang et al. sp. nov. The white speckle disease of the garrupa is caused by a parasitic ciliate. It is foundto be a new species belonging to a new genus of Chlamydodontidae. The ciliates attackthe gills and the skin of the garrupa. The new genus (Petalosoma Huang gen. nov.)possesses both the petaloid body andthe cytostome simultaneously, and so it is quite different from the other five genera ofChlamydodontidae. The type species of this genus is Petalosoma epinephllis Huang et al.sp. nov.. The new species has the body length from 45μ to 80μ (average 67μ) and widthfrom 29μ to 53μ (average 39μ). Its ventral side bears 32-36 rows of cilia. The oralbasketris formed by 12 trichites. There is a petaloid body in the rear of the cell. 2. Symptom: The parasites irritate the skin and gills of the fish, thereby, large quantity ofslime was secreted. The skin appeared white speckles. The infected fish always swimsslow and breathe with difficulty. It would cause high mortality. (a) Bathe the diseased fish in freashwater for 4 minutes.(b) Bathe the diseased fish in 2 ppm. copper sulfate solution for two hours andrepeat text day.