Aquatic Fungi and Fungal Diseases of Fish: A Review

Aquatic fungi have the potential to cause serious diseases in almost all freshwater and few marine fish species and their incubating eggs. The number of identified infectious fungal and fungal-like pathogens grows every year worldwide. Saprolegniasis, branchiomycosis, epizootic ulcerative syndrome (EUS), ichthyophoniasis, and exophialasis are the most common fungal diseases of fish. Saprolegniasis is an economically important fungal disease that affects freshwater and some estuarine fish species in warm and tropical regions. Another common agent of fungal infections is species of Achlya infecting fish; however, there is no consistent clinical diagnosis for Achlya . The common fungal infection of fish gill tissue is known as branchiomycosis, also called gill rot. EUS is a highly important seasonal epizootic disease in wild and farmed fish of freshwater and estuarine origin. Ichthyophoniasis is an internal infection causing chronic, systemic, granulomatosis disease. Exophiala species are opportunistic fungal pathogens that may infect a broad range of warm- and cold-blooded animals. The purpose of this review is to provide a comprehensive overview of these fungal diseases that affect many fish populations, shedding light on their epidemiology, clinical manifestations, and existing control measures. The review aims to enhance awareness and understanding of these diseases, emphasizing the importance of early diagnosis and prevention in managing fungal infections in both wild and aquaculture settings.