Fungal Infections in Some Economically Important Freshwater Fishes

Abstract

Aim of this study was to investigate fungal infections in four species of carps including goldfish, Carassius (C.) auratus L.; silver carp, Hypophthalmichthys (H.) molitrix Richardsons; rahu, Labeo (L.) rohita Hamilton and Ctenopharyngodon (C.) idella Valenciennes. Nine specimens of each species were studied for the presence of fungal infections. Infected fishes showed clinical signs such as fungal growth on skin, fins, eyes, eroded fins and scales, hemorrhages on body surface and abdominal distension. The specimens from infected organs of fish were inoculated on each, malt extract, Sabouraud dextrose and potato dextrose agars. The fungal colonies of white, black, green, grey and brown colors were observed in the agar plates. Slides were prepared and stained with 0.05% Trypan blue in lactophenol. C. auratus showed the highest infection rate (44.4%) followed by H. molitrix and L. rohita (11.1% each). Five fungal species viz. Aspergillus (33.3%), Penicillium (22.2%), Alternaria (27.7%), Blastomyces spp (11.1%) and Rhizopus (5.5%) were isolated. Posterior part of the fish had significantly (P=0.05) higher (62.5%) infection as compared to anterior part (37.5%). The caudal fin with 31.25% infection was the single most affected area. This study showed that most of the fungi isolated from fishes are considered as normal mycoflora, yet many fungi can cause natural infections in ponds and aquarium.

Keywords

• Carassius auratus
• Ctenopharyngodon idella
• Fungal infections
• Hypophthalmichthys
• olitrix
• Labeo rohita