Monitoring of fresh water fish farms in north of khouzestan province for mortality emphasis on silver carp

Abstract

Carp fishes culture is one of the most important subsector fisheries industry in Khouzestan province. Every year in summer high mortality occurred in carp fishes farms specially in silver carp of north Khouzestan province. Inspection of silver carp for identification microorganisms agents (Bacteria, Fungi, Parasite and virus: SVC,KHV), determine total plate count, examination physic chemical factors of farms water, histopathology, identification planktons, the main objectives of this study, which was held in 2012. 180 silver carp from 5 farms (10 ponds) with high mortality in years ago were collected in north Khouzestan province and then differents parts of fish body including: intestine, gills, body surface, eyes and liver were examined. Physico chemical parameters and plankton sampled monthly. Physico chemical parameters of water were measured all over culture period for 960 times as follows: Do(4.45-8.5 ppm), BOD5(1.1-9.25 ppm), temp(19-33•c), pH(6.82-8.6), total hardness(348-10053), turbidity(5-56 FTU), Amonia(0.001- 0.06 ppm) and co2( 0.88-13.2). From a total 180 fish examined, 136 (75%) showed unknown algae infestation and 126 (70%) showed parasitic (Dactylogyrus, Gyrodactylus and metacercaria Diplostomum). The results of biotic parameters in farms showed that cyanophycae (Cylindropermopsis, Merismopedia and Nitzeshia) were the most group of phytoplanktons. Histopathological studies have shown necrosis in tobules kidney, degeneration hepatocyte and hyperplasia in gill cells and also results demonstrated the mean of total plate count (0-376 CFU/ml103). 60 samples with sighn severe hemorrhagic on surface body were collected for virology studies by PCR procedure (IQ2000 kit) and have shown which 3 sample suspected to KHV but SVC was not identified.