Some mycological in vestigations on cultured tilapia in Kafr El-Sheikh governorate

الملخص EN

This study was carried out on 193 freshwater cultured tilapia (Oreoc-hromis niloticus) collected from the Military unit of fish production at Kafr El.

Sheikh Governorate in different seasons.

Fish were 118 appa-rently healthy and 75 clinically diseased fishes.

The clinical and post-mortem examination of naturally infected fish revealed the presence of clinical abnormalities in the form of skin darkening, exophthalmia, slight abdominal distension, necrotic foci with sloughing of tail and body fins, haemorrhages at the base of fins especially the pectoral and dorsal fins with peticheal haemorrhages at the base of scales, cotton wool like growth on various parts of the skin of naturally infected O.

niloticus, detached scales with sloughing of the uppermost layers of skin, discolouration of gills, abnormal and dark skin in some fish were seen.

In the postmortem examination, the liver, kidney and spleen were congested and friable.

The liver of some fish showed pale brown colour with or without hemorrhagic patches.

Gall bladder was gener-ally distended with bile; also ascitis and enteritis were reported in some cases.

Isolation of different fungi and yeasts on Sabouraud's agar with chloramphenicol revealed the presence of Aspergillus flavus (166 isolates), Aspergillus.

niger (136 isolates), Penicillium (98 isolates), Alternaria (164 isolates), Cladosporum (93 isolates), Fusarium (196 isolates), Mucor (86 isolates), Saprolegnia (47 isolates) as well as yeasts including Rhodotorulla (154 isolates) and Candida albicans (169 isolates) from skin, fin, gills, gas bladder, kidney, spleen and liver of both apparently healthy as well as diseased tilapia.

Experimental infection with the most common fungal isolates including, Aspergillus flavus, Fusarium and Candida albicans revealed the pres-ence of different percentages of moralities in different fish groups infected experimentally by skin scarification.