Studies on the Toxico-Biological Behaviour of Extracellular Toxic Substances of Toxigenic Fungi For Fresh water Fish

This study was conducted on a total number of three hundred and thirty fivesamples of fish ration and fish ration ingredients. One hundred and eightyfrom fish meal, eighty from yellow corn and seventy five from fish ration,all samples were collected from Animal Health Research Institute Dokki,from Markets, from Abbasa Fish Hatchery in Sharkia Governorate and fromNawa farm in Kalyoubia Governorate.One hundred apparently normal Nile Tilapia fish (Oreochromisniloticus) of different weights (60-80g) were obtained from Foky center atNowa farm in Kalyoubia Govemorate for experimental infection. Eighteen clinically normal Nile cat fish (Clarias species) at weights (l50-200g) collected from private fish farms in Sharakia Govemorate to be used as a biological indicators (skin test ).The results of mycological studies revealed that from fish meal 335isolates related to 5 genera and 18 species were recovered, from fish ration175 isolates related to 5 genera and 19 species were isolated and from yellow corn 140 isolates related to 4 genera and 16 species were isolated. Five genera of different fungi were isolated from fish meal, fish ration andfour genera from yellow corn . The genus Aspergillus was the mostpredcminant isolates with occurrence of (88.05 % ), it was isolated fromexamined samples followed by Penicillium species with occurrence of(37.3 %), Fusarium species with occurrence of(34.3 %), Mucor specieswith occurrence of(25.3 %), Alternaria species with occurrence of( 7.4 %)and Scopulariopsis species with occurrence of (4.4%) .