The introduction of L. vannamei to Iran from Hawaii was initiated when high mortality occurred in shrimp farms of Abadan in 2002 than in Bushehr during summer of 2004. Inspection of L. vannamei for infectious agents (Bacteria , virus , fungi and parasite ) , determine total plate count and total vibrio in Bahmanshir Rivers, shrimps and farms water , examination physicochemical factors of farms water , Identification of carriers of wssv in wild shrimp and crabs , the main objectives of this study , which was held in 2007 . 540 shrimp samples (pl12 pl15) and subadults were collected from different shrimp farms in khouzestan province and then check for identity bacteria, fungi and parasite. Also 280 samples of L. vannamei , wild shrimps ( Metapenaeus af inis , Exopalaemon styliferus ) and crabs (Grapsus sp .and Sesarma sp. ) were Collected from Bahmanshir river for virology studies by PCR procedure (Iq2000 kit WSSV , IHHNV , TSV ) . 120 samples of L. vannamei for histopathology had been collected randomly and preserved in Davidson’s fixation and then transferred to 75% ethyl alcohol for storage. (Hepatopancreas gills). Physicochemical parameters of water in culture ponds comprising of pH DO, BOD, NO_3, NO_2, salinity. Total. Hardness and NH3 were measured all over culture period for 340 times. Finally it has been detected 10 genus and species of bacteria consisting of V . alginolyticus, V. parahaemolyticus, V. proteolyticus , plesiomonas shigelloides ; 6 genus and species of fungi specially Aspergilus niger , Asp.fumigatus and Asp.flavus and two genus of parasites vorticella sp. And Zoothamnium sp. were isolated. Crab (Sesarma sp.) were tested by using Iq2000 diagnostic kit for WSSV that positive for WSSV. There was a positive result (three viruses TSV, IHHNV and WSSV) for postlarvae and subadults of L.vannamei by using Iq2000 kit and IFRO kit (Internal kit). Histopathological studies have shown inclusion bodies of TSV, WSSV, IHHNV, MBV and HPV in various tissues. Results demonstrated the mean of vibrio count (0. 01×103 - 1.96 ×103) and tolal plate count (0 .21 ×103 - 14.25 ×10 3). physicochemical parameters of water were measured as follows : salinity (12.3 22.5 ppt ).BOD5 ( 1.98 10.21 ppm ) , DO (3.17 11.25 ppm ) , NH3(0.02 3.45 ppm ) and temperature (20 31. 5 c) . Keywords: L.vannamei, bacteria, virus, fungi, parasite Histo pathology - physicochemical parameters of water- Abadan khouzestan province
