الفهرس 
Materials and mithodsOnly 14 pages are availabe for public view
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Abstract
The investigation of 180 Armout catfish were collected from different localities. Fish was Examined clinically which grouped the collected fish into 30 apparently healthy fish and 150 fish had different clinical abnormalities.
The results of bacteriological examination of 30 apparently healthy Armout catfish revealed the isolation of 76 different bacterial isoiates. Aeromonas hydrophila were found to represent the most commonly isolated bacteria from apparently healthy Armout catfish where 40 (52.63%) isolates were recovered. Other bacteria were isolated in much lower numbers including, Shigella dysenteriae 5 (6.57 %), Pseudomonas aeniginosa and E. coli (5.26 %), each. Three isolates (3.94 %) from each of Plesiomonas shigelloides, Klebsiella pneumoniae, K. oxytoca, Staphylococcus aureus, Staphylococcus epidennidis and Streptococcus faecalis. Proteus mirabilis and Proteus vulgaris 2 (2.63 %), each of them and one isolate (1.32 %) for Salmonella species. The intestine yielded the highest rate of isolation (36 isolates), followed by liver (13), gills (11), skin (8), heart (4), while the lowest number of isolates were from gall bladder and kidneys (2, each) and there was no isolates recovered from spleen samples.
The mycotic examination of 30 apparently healthy Armout catfish revealed the isolation of 61 different fungal isolates. The most prevalent. fungal isolates were Aspergillus niger 15 (24.59%) isolates Aspergillus flavus 13 (21.31 %), Aspergillus fumigatus 7 (11.47 %), Mucor and Rhizopus species 6 (9.83 %), each. Other types were isolated in lower numbers included, Rhodotorula fujisanense 3 (4.91 %); Penicillium vemicosum, Penicillium chlysogenum, Geotrichum candidum, Candida albicans and Candida foliorum 2 (3.27 %), each. Cryptococcus neoformans one isolate (1.63 %).
Also the intestine yielded the highest rate of isolation among other organs (31 isolates) followed by gills (12), liver (6), skin (4), gall bladder (4), heart (3) and kidney one isolate.
Bacteriological examination of 150 diseased Armout catfish (Clarias lazera) revealed the isolation of 218 different bacterial isolates. Aeromonas hydrophila were found to represent the most commonly isolated bacteria from clinically diseased Armout catfish , 120 (55.04%) isolates were recovered. Other bacteria were isolated in much lower numbers such as, Plesiomonas shigelloides 12 (5.50 %), Salmonella species (10) (4.58%) E. coli and Shigella dvsentriae 8 (3.67 %), each, Klebsiella pneumonae., Klebsiella oxytoca and Pseudomonas aentginosa 6 (2.75 %), each. Five isolates (2.29 %), for each of Pseudomonas fluorescens, Proteus mirabilis Streptococcus faecalis and Staphylococcus aureus. Edwardsiella tarda Proteus vulgaris and Serratia marscecens 4 (1.83 %) for each of them; 3 (1.37 %) for each of Citrobacter freundi and Staphylococcus epidermidis and 2 (0.91 %)for
E0 each of Staphylococcus citrus and Corynebacterium species. The highest rate of isolation was obtained from the intestine (68 isolates) followed by liver (43), heart (37), kidneys (16), while the lowest number of the isolated bacteria were recovered from skin, spleen, and gall bladder and spleen (12,11 and 10 isolates respectively).
Mycotic examination of 150 diseased catfish (Clarias lazera) revealed the isolation of 159 different mould and yeast isolates. The most commonly fungal isolates associated with clinically diseased catfish within the present results were Aspergillus flavus 36 (22.64 %) isolates, followed by Aspergillus fumigatus 26 (16.35 %) , Aspergillus niger 23 (14.46%), Mucor species 15 (9.43 %) and Candida albicans 13 (8.47%). Other types of fungi were also isolated in much lower numbers including, Rhizopus species 7 (4.40%), Penicillium chrysogenum 5 (3.14 %) , Penicillium gresiofulvum and Cryptococcus neoformans 4 (2.51%), each. Three isolates (1.88%) for each of Aspergillus clavatus , Rhodotorula species,,Fusarium and Acremonium species; Aspergillus ochraceus, Penicillium verrucosum, Penicillium expansum, Absidia species and Alternaria species 2 isolates (1.25 %) for each of them . One isolate (0.62 %)for each of Penicillium citrinum , Pacilomyces, Cladosporium and Fonscecae.
Also, the results revealed that the highest rate of isolation was obtained from the intestine (60) isolates followed by liver (40), gills and spleen (16) while the lowest number of isolates was recovered from kidney (8), skin (6), and gall bladder (3).
As the present results concerned with the evaluation of different stress factors that may affect the viability and pathogencity of microbial
fish pathogens.
The effect of some factors on the growth of Aeromonas hydrophila in brain heart infusion broth and revealed that, highest growth was obtained at pH 7 and 8, also, at Nacl concentrations 0.5 and 1.5 % and at temperature degrees of 35,30 and 25°C respectively. On the other hand, Aspergillus flavus growth was well observed at Nacl
0.5 % and 1.5 %, also.
Experimentally inoculated Armout catfish with Aeromonas hydrophila under the influence of different degrees of temperature revealed that high mortality rate was observed at 35°C, 30°C and 25°C respectively, within 4-10 days with severe clinical and internal lesions. But under the effect of different pH values all fish groups showed 40 % mortalities after 10 days except at pH 9 the mortality was 40 % after 7 days. Under the influence of different concentrations of Nacl, the mortality reached 100 % at Nacl 10, 5, and 2.5 % after 3, 7 and 15 hours respectively. The fish remained alive at Nacl 1.5 and 0.5 % with moderate clinical and internal lesions. Re-isolation of the same inoculated microorganism from fish was performed Experimental inoculation of catfish with Aspergillus flavus under the influence of different degrees of temperature, different pH values and different concentrations of Nacl was also practiced. Higher mortality rate were observed but the incubation period of the disease took longer time than fish inoculated with Aeromonas hydrophila and reisolation of the inoculated fungus was also done.
Armout catfish was inoculated with mixed Aeromonas hydrophila and Aspergillus flavus microorganisms under the influence of different degrees of temperature, different pH values and different concentrations of Nacl. The mortality rate was higher than the catfish inoculated only with Aeromonas hydrophila or Aspergillus flavus with severe clinical signs and post-mortem lesions and also both inoculated microorganisms were reisolated.
Conclosion :
Several types of bacteria and fungi were isolated from both apparently healthy and diseased catfish (showing clinical abnormalities) which may be considered as primary or secondary bacteral and mycotic agents for fish. Their isolation from both healthy and diseased fish reflects the role of different stress factors on the fish and fish farms. The increase in environmental temperature leading to the increase in mortality and morbidity of fish which necessiates prompt control and vaccination programs during summer months in Egypt. In addition, detailed studies should be applied on the nature of the soil, in respect of salinity, pH and chemical composition before constructing fisheries