Further studies on pathogenic cytophagales in fresh water fishes

World aquaculture had grown tremendously during the last years becoming an economically important industry. Today it is the fastest growing food-producing sector in the world with the greatest potential to meet the growing demand for aquatic food. CytophaDuring this study, a total number 150 of naturally infected fishes were used for the isolation, identification and molecular differentiation of isolated F. columnare strains by RAPD-PCR and SDS-page. Beside a total number of 780 apparently healthy live fiThe results revealed that:-1- Naturally infected fishes with F. columnare were appeared lethargy, off-food and loss of balance with respiratory manifestations. Fin rot was observed. Skin lesions appeared as whitish, yellowish or yellowish white mucoid exudates with red hemorrhages 2- F. columnare were isolated from fins, skin slime , gills and kidneys of naturally infected fishes. The cultural characteristics of F. columnare on Ordal´s media were growing of flat irregular whitish yellow creamy colored colonies in the presence of ne3-The isolated F. columnare from different fish species had no clear significant genetic variations. However, the total amount of the protein which is present in the cell wall of each isolate was completely different.4- F. columnare isolates were highly sensitive to Oxytetracycline, Erythromycin, Kanamycin and Nalidixic acid and resistant to Ampicillin, Chloramphinicol, Doxicyclin, Neomycin, Penicillin and Sulphamethoxazol.5- Variable percentages of mortality among the experimental infected fishes by F. columnare which were ranged from 40 to 100% .6- Fishes received B. subtilis’’probiotics’’ for 12 weeks either in water or in diet significant increase in final body weight, body gain percentage and specific growth rate percentage in comparing with fishes which fed on basal diet.7- Fishes received B. subtilis’’probiotics’’ for 12 weeks in diet showed significant increase in final body weight, body gain percentage and specific growth rate in comparing with fishes received B. subtilis ’’probiotics’’for 12 weeks in water.8- There were insignificant decreases in final body weight but there were significant decrease in body gain percentage and SGR% before, after infection with F. columnare and then after the stopping of B. subtilis ’’probiotics’’.9- The level of IgM in fishes in different condition showed no significant variations among fishes received B. subtilis ’’probiotics’’ for 12 weeks either in water or in diet. W