Branchiomycosis (Gill Rot Disease)

o   Common Clinical signs

The infected fish suffered weakness, lethargy and respiratory distress resulting from gill tissue damage, represented by swimming in a vertical position to gasp the air, surfacing, and accumulating at the water inlet with rapid operculum movement and eventually, dying with an open mouth. Primarily, appeared congested in the early stage and then showed the beginning of tissue paleness due to loss of oxygenation. The color of the gills began to turn white because of necrosis, and eventually, bright, white-colored gills in advanced cases of infection. The disease progressed as a result of severe necrosis of gill tissue which gave gills the marbling appearance (Mahboub and Shaheen, 2021) (Fig.1; A, B, C).

Fig. 1: A) Gills showed severe congestion in the acute course.  B) Gills showed a marbling appearance in the acute course. C) Gills look bright white colored in advanced cases of infection with severe necrosis.