Survey on Causative Agents and the Incidence of Streptococcosis in Selected Farms of Rainbow Trout in Dasht-e-arjan and Kohmareh of Shiraz

In order to survey on the causative agents and the occurrence of suspected disease to
Streptococcosis in some farms of rainbow trout in the areas of Dasht-e-Arzhan and Kohmareh in Shiraz province, 100 specimens of live fish with symptoms similar to Streptococcosis were caught and After dissection, bacterial sampling were taken from kidney, liver and brain then cultured on Blood Agar media. Samples were stored in the incubator at a temperature of 25 -30 ° C for 48 hours. After this time, at first gram negative samples were removed by using gram stain technique and catalase test. then the supplementary biochemical tests were performed after recultivating of the samples. The results showed that the samples isolated from the two species, Streptococcus iniae and Lactococcus garvieae. The occurrence of fish with clinical symptoms was 77% to S. iniae and 13% to L.garvieae and no Infection isolated from 10% of the samples.