الفهرس 
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Abstract
This study was carried out on 360 freshwater fishes (240 Oreochromis
species and 120 Clarias gariepinus). They were collected from Kafr El-Shikh,
Sharkia, and Giza governorates and during different seasons. Naturally infected
fishes showed clinical abnormalities such as skin darkening, exophthalmia, corneal
opacity, abdominal distention, ulceration of the skin and cotton wool like growths
on various parts of the body. Fishes were then subjected to post mortem
examination which revealed many abnormalities. Mycological examination
revealed the isolation of 2081 fungal isolates from 150 diseased and 210
apparently healthy fish samples (1658 mould and 423 yeast isolates), of which
1334 were isolated from Oreochromis species and 747 isolates from Clarias
gariepinus. Isolated moulds belonged to the following genera: Saprolegnia (4.2%),
Aspergillus (43.0%), Fusarium (14.1 %), Mucor (14), Penicillium (17.2), Rhizopus .
(4.8%), Scopulariopsis (1.2%), Paeciliomyces (1%) and Curvularia (0.4%). Yeasts
isolated also from both fish species had the following incidence: Candida albicans
(35.9 %), other Candida species (19.1%), Rhodotorula species (31.4%) and
Torulopsis species (13.5%). Experimental infection with the most predominant
fungi (Aspergillus flavus, Fusarium species and Candida albicans) was conducted
to evaluate the pathogenicity of these isolates. Clinical pictures of experimentally
infected fish were similar to those of natural infection. Inoculated fungi were re-
isolated from different organs. Results were confirmed with histopathological
examination, which revealed the presence of fungal hyphae and spores in different
organs.