الفهرس 
INTRODUCTION AND REVIEWOnly 14 pages are availabe for public view
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Abstract
This work started by taking water samples randomaly from the earthen ponds o fFish Production, Central Laboratory for Aquaculture Research, Abbassa, Abu-Hammad, Sharkia. Water analyses and isolation of some species blue green algae that presented in this water were done. The blue green algae were (Anabaena, Oscillatoria and Lyngbya sp.). Anabaena wisconsinense and Oscillatoria curviceps were selected to study their antimicrobial effect. The present investigation indicated that the growth curve of Oscillatoria curviceps was between 14-16 days and for Anabaena wisconsinense ranged between 16-18 days of incubation. The cells were harvested in the logarithmic growth phase and extracted by different organic solvents such as ethanol, methanol and chloroform using a soxhlet extractor. Different species of pathogenic bacteria were isolated from diseased fish and identified as Gram +ve (Lactobacillus sp. and Bacillus firmus) and Gram -ve (Aeromonas hydrophila, pseudomonas fluorecence and Pseudomonas anguilliseptica). Aspergillus niger was isolated from muscles of apparently healthy common carp, Saprolegnia parasitica was obtained from fish diseases department, Central Lab Aquaculture Research in Abbassa, Agriculture Research Centre, Egypt. That was isolated previously from diseased fish.