Parasitic
🔴 Fatal
✓ Treatable
Oodinium (Velvet Disease)
🦠 Amyloodinium ocellatum (marine), Piscinoodinium pillulare (freshwater) · Oodiniaceae (Dinoflagellata)
📋 Overview
Velvet disease is one of the most dangerous parasites of marine aquarium fish. Amyloodinium trophonts embed in gill epithelium and derive nutrition from host cells. Each trophont produces hundreds of infective dinospores, making the disease spread explosively. The marine form is harder to treat than freshwater Ich. Darkness slows dinospore release.
📊 Key Facts
Causative Agent
Amyloodinium ocellatum (marine), Piscinoodinium pillulare (freshwater)
Agent Family
Oodiniaceae (Dinoflagellata)
Geographic Range
Worldwide in marine (Amyloodinium) and freshwater (Piscinoodinium) systems
Transmission Routes
Free-swimming dinospores in water
Primary Host
Wide range; marine fish, tropical aquarium fish
Vaccine
✗ None / Experimental
🩺 Clinical Signs
Fine golden-yellow to rust-coloured dusting on skin/fins/gills (visible in raking light), rubbing/flashing, rapid opercular movement, clamped fins, laboured breathing, weight loss, mass mortality.
🔬 Symptoms
🔬
Golden-yellow dust on skin
Integumentary Subacute
🔬
Rapid opercular movement
Respiratory Acute
🔬
Flashing/rubbing behaviour
Integumentary Acute
🔬
Clamped fins
Integumentary Subacute
🧪 Diagnosis
Wet mount of skin scrape or gill biopsy showing pear-shaped trophonts with dark pigment inclusions.
💊 Treatment
Copper sulphate (marine), chloroquine (marine), acriflavine (freshwater), formalin, increased temperature + hyposalinity (marine).
🛡️ Prevention
ℹ️ Prevention is the most effective strategy for managing this disease in aquaculture and aquarium settings.
Quarantine all new arrivals minimum 4 weeks, UV sterilisation, avoid introducing infected fish.