Fungal diagnosis
The diagnosis of fungal infection was based on the appearance of cottony mycelial growth on the surface of the fish. Saprolegnia infection was identified by their morphological characters on Nile tilapia by direct microscopic examination of lesion and mycological culture on glucose yeast extract (GY) agar at 19°C. Identification was based on the classical morphological criteria of Seymour (1970) and Willoughby (1978, 1985). The numbers of fish mortalities, moribund and surviving fishes were recorded. The dead fish and controls were also collected and subjected to analysis.