Ali asghar Saeedi - The Ecological Institute of Caspian Sea
Hossein ali Rostami - The Ecological Researeh Station of Caspian Sea

Bacterial flora and parasitic fauna of M.Leidyi an exotic invader jelly fish to Caspian sea ecosystem and B.ovata as an alternative biological control agent was studied during July 2003 - July 2004. using routine bacteriological works , examination of 72 samples of M.leidyi and sea water obtained from Caspian sea in 20 and 50 meters depths and 10 samples from B.ovata 3sample of black sea water obtained from black sea region out of vibrio harveiy, Bacillus linens and Shewanella which are present in high salinity of open sea and ocean .and abserved in B.ovata and black sea water but other bacteria include Agrobacterium ,Chromobacterium , Micrococcus ,Aeromonas , bacillus –coagulans in each both ctenophore ( M.leidyi water Caspian sea and B.ovata ) was abserved and reported .No parasite fauna was identified in M.leidyi , while B.ovata was contained with Trichodina Ctenophora at various concentrations . B.ovata kept at higher salinity of 21 ppt was more contaminated with this pretrichial protozoan than in lower salinity(12/6 ppt ) . Although , more works are required to identified bacterial flora and parasitic fauna of B.ovata as a possible alternative biological control agent of M.leidyi.