A survey on some risk factors and evaluation of their impacts on streptococcosis in rainbow trout farms in some provinces in IRAN. (Mazandaran, Fars)

Abstract

One of the most important bacterial fish diseases which has caused some outbreaks in rainbow trout farms in Iran is streptococcusis .The farmers were suffering from huge economic losses due to the disease outbreaks in different rainbow trout farms in Iran. The aim of our study was to determine rate of streptococcusis incidence in different stage of growth in farmed rainbow trout in Mazandaran and Fars province. Fish and water samples were randomly collected and measured randomly in selected farms, monthly throughout a year. After clinical observations, Isolation and recognition of strep strains were made using biochemical and molecular tests. Some Environmental factors include Nitrate, Nitrite, Temperature, pH, Ammonia and DO measure during sampling periods. According to our results incidence of disease in juvenile is more than growers. Some samples showed clinical singe of streptococcusis without strep. Contamination .Main isolated strain were S.iniae and S.garviea and S.uberis recognized for first time in east of Mazandaran province (Haraz River). Incidence of streptococcusis in rainbow trout affected by fluctuation of Nitrite, temperature and DO. Management of these factors can decrease rate of disease outbreaks.