الفهرس 
Table of ContentsOnly 14 pages are availabe for public view
 |  | from | 143 |  |  |
| | | from | 143 | | |
Abstract
Bacterial diseases produced the most common problems of the diseases among the cultured fish in Egypt. Most of these pathogens were normal inhabitant in fresh and also in marine water (Bondad-Reantaso et al., 2005).from this study, it was founded that the outbreak which had been happened in hundred numbers of Nile Tilapia farmed in Gamsa Area and Manzala Area in summer and winter season due to bacterial and fungal infection respectively. The symptoms of the diseases were the same in two farms from the history of the farm found that the outbreak had been happened in the same time in last year but in this outbreak the mortality was more than last year.The most clinical signs recognized during the outbreak were hemorrhagic batches, erosion, discoloration of the skin and sometimes presence of ulcers, sloughing of scales, erythema and congestion at the base of the fins, mouse, operculum and around the eye (exophthalmia of the eye), congestion on gills and covered with mucous and abdominal distension. Some of fish had other clinical signs as a fish had a cotton wool mass on the skin, fins and might cover the eyes this result agreed with the results of (Jafar et al., 2009).from the post mortem examination of the infected fish found that signs of general septicemia as liver were enlarged in size, hypermic ranged from yellow to dark brown in color has petechial hemorrhagic and necrotic foci and gall bladder was over distended with bile. The spleen was over distended with bile. The spleen was enlarged in size and congested. The intestine was hyperemic, empty from food and contain yellowish or bloody mucous. The body cavity cloudily fluid sometimes bloody. The gonads were swollen, congested with abnormal colors.The colonial and cultural characters of A.hydrophila as the colonies were rounded smooth colonies 2-3 mm in diameter and yellow to orange colored colonies on R-S media and also biochemical tests as catalase positive, oxidase positive, indole production, cytochrome oxidase positive and voges proskaure revealed to presence of gram negative motile coccobacilli rod shape and this result as a result of(Carson et al., 1993).Recording also in this study the microscopic examination of morphological characters of saprolegial isolates which showing branched filament with non sepetated hyphae spores this result as this recorded with (Bian et al., 1979).In this study, the total prevalence of bacterial isolates in two farms was A.hydrophila (77.19%), Ps.fluorscence (9.66%), E.coloacae (7.017%), V.fluvialis (3.51%) and Citrobacter frundii (2.63%). In this study PH value was about (7.8 -8.6) in Aeromonas outbreak but on Saprolegniasis outbreak is about 7.6.Furthermore the dissolved oxygen level in this study was (3.8 & 4.3) during Aeromonas outbreak and (4.1) during Saprolegniasis outbreak and this blow the normal level according to (Sandhya and Benarjee, 2016).In this study the level of non-ionized ammonia in Aeromonas outbreak was about 0.18in Gamasa farm and 0.25 in Manzala farm so the recorded results of ammonia level in Manzala Farm was higher than that level on Gamasa Farm.from this study we can conclude that:Bacterial diseases produced the most common problems of the diseases among the cultured fish in Egypt. The second type of diseases after bacterial infections was fungal diseases and had a huge economic importance.Motile Aeromonas septicemia was a dangerous bacterial disease affect cultured fresh water fish especially under intensive breeding caused high morbidity and high mortality.Saprolegiasis was the most important mycotic disease due to high mortality rate among Nile Tilapia.A.hydrophila was sensitive to ciprofloxacin more than erythromycin, Nalidixic acid and Nitrocycline and resistant to colistin sulphate, lincomycin and trimethoprim / sulphamexathole.The presence of bad quality water or bad management had been acted as stress factor, which enhance the disease incidence.The addition of vitamins, Minerals and antibiotic on half of therapeutic dose as a prophylactive treatment on the diet and providing good quality food to make increasing immunity of fish.