First record of ecto Epistylis sp. on free-living fish in the lake of the 16 Tishreen dam

The study included 144 Free – living fish from the Lake of 16 Tishreen Dam, collected randomly during the period from 12/2011 until 11/2012, on monthly basis to detect the infection with Epistylis sp. and determine its distribution rate. Fish samples were: Cyprinus carpio L., Varicorhinus damascinus, Garra rufus, Tilapia zilli, and Liza abu. Tilapia zilli was the most prevalent in the lake of 16 Tishreen Dam. The study revealed fish infection with Epistylis sp. on free – living fish in the Lake, with a total infection rate 22.22 % , mainly on Tilapia zillii (29.70 %) and then on mullet (2%);No infection with Epistylis sp. Was recorded on the other fish species. The infection with this ecto Epistylis sp. was recorded for the first time in Syria in our study. The infection with Epistylis sp. was located on the skin, fins and gills. The highest infection rate was on the fins ( 42.34 %) , followed by skin (37.46 %) , and then by gills (1.87 %) . The infection with Epistylis sp. had the highest rate in summer ; i.e. during high temperature , low concentration of dissolved oxygen , and slightly high value of BOD. The study showed that, the water of 16 Tishreen Dam is relatively clean.