Aquatics True Fungal Infections Study Guide

Overview and Clinical Importance

True fungal infections in aquatic species represent an important but often underdiagnosed category of diseases in veterinary aquatic medicine. Unlike the more common water molds (Oomycetes) such as Saprolegnia, true fungi belong to the Kingdom Fungi and possess chitin-containing cell walls rather than cellulose. These organisms include Aspergillus, Fusarium, Exophiala, Branchiomyces, and Ichthyophonus (now reclassified as a mesomycetozoean but historically considered fungal).

True fungal infections can cause devastating systemic disease, particularly in captive marine species like elasmobranchs and ornamental fish. Aspergillus species are particularly important due to their role in mycotoxicosis (aflatoxicosis) through contaminated feed, which represents a major economic and health concern in aquaculture worldwide.

Classification of Aquatic Fungal Pathogens

Understanding the distinction between true fungi and fungal-like organisms is essential for appropriate diagnosis and treatment. True fungi have chitin-containing cell walls and reproduce via spores, while Oomycetes have cellulose-based cell walls and produce motile zoospores.