Freshwater Tropical · Marine / Saltwater
Velvet (Oodinium)
Dinoflagellate parasite producing a fine, gold-dust coating across the body. More lethal than ich; gill infection causes rapid death.
Severity: Severe
*Amyloodinium ocellatum* (marine) and *Piscinoodinium pillulare* (freshwater) are dinoflagellate parasites. Unlike ich, they photosynthesise — so darkening the tank during treatment slows their reproduction. The infection is **more dangerous than ich** because it preferentially infects the gills.
Causes
Introduced via new fish. Outbreaks accelerate at warm temperatures and bright light.
Treatment
**Marine**: copper at 0.15–0.20 ppm for 14 days OR chloroquine phosphate at 40 mg/L for 14 days. **Freshwater**: **Forma-Green** for 10–14 days. Darken the tank during treatment.
Recommended medications
Antifungal
Forma-Green
Formaldehyde + malachite green combination — broad-spectrum treatment for ich, costia, trichodina, oodinium, and fungal infections.
from $24.00
Recommended equipment
Hardware that prevents, monitors, or treats this condition — listed with the most important first.
Monitoring
Microscope for Fish Health
Definitive parasite and pathogen identification
from $100–$800
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Water Testing
Copper Test Kit
Copper toxicity monitoring during parasite treatment
from $500
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Water Testing
Salinity Meter / Refractometer
Marine fish stress, coral disease
from $80–$160
View details →Prevention
Quarantine. Cover quarantine tanks to reduce light.