Systemic phaeohyphomycosis in splitnose rockfish (Sebastes diploproa) caused by Devriesia sp

Area of Science:

• Veterinary Mycology
• Aquatic Animal Medicine
• Pathogen Discovery

Background:

• Splitnose rockfish (Sebastes diploproa) are marine fish susceptible to various diseases.
• Ocular diseases in fish can lead to significant morbidity and mortality.
• Identifying novel pathogens is crucial for understanding fish health.

Observation:

• Two juvenile splitnose rockfish presented with severe ocular lesions, including buphthalmia and corneal plaques.
• Cytologic and histologic examinations revealed fungal hyphae and granulomatous inflammation within ocular and cardiac tissues.
• The observed clinical signs indicated a severe systemic and ocular fungal infection.

Findings:

• The causative agent was identified as a fungus with specific morphological characteristics (slender, hyphenated, branched, parallel cell walls, brown pigmentation).
• Molecular identification using the nuclear ribosomal RNA internal transcribed spacer (ITS) segment classified the fungus as Devriesia sp.
• This represents the first report of Devriesia sp. causing disease in any animal species.

Implications:

• This study identifies a novel pathogen, Devriesia sp., responsible for phaeohyphomycosis in fish.
• The findings expand the known host range and pathogenic potential of Devriesia species.
• Further research is needed to understand the transmission, pathogenesis, and treatment of this emerging fish disease.