Seasonal Variation of Diplectanid Monogeneans in Cage Cultured Seabass from Bangpakong River, Thailand

Inthis study, monogenean gill parasites in cage cultured seabass (Lates calcarifer) in three farms were investigated between June 2010 to June 2011. The farms (A, B, C) represent the three salinity zones in seabass cage culture in Thailand. Three species of diplectanid monogenean, Laticola lingaoensis, L. paralatesi and Diplectanum penangi, were isolated from 691 seabass. The prevalence values of parasites from the three farms were more than 90%. L. lingaoensis was the most dominant parasite followed by  L. paralatesi and D. penangi, respectively. The mean intensity of monogenean parasite species was highest in Farm B which was statistically different (p<0.05) followed by Farm A then Farm C. The prevalence of gill parasites was high in all farms in both dry and rainy seasons. Inaddition, the mean intensity of gill parasites in Farms A and B showed a high rate of infection during the dry season.