Marine velvet is the deadliest common saltwater fish disease. Caused by the dinoflagellate parasite Amyloodinium ocellatum. Kills within 48-72 hours when established. Symptoms: gold-dust appearance on body and fins, rapid breathing, flashing.
Causative organism: Amyloodinium ocellatum
Severity: Critical (high mortality)
Velvet kills fast. Within hours of identifying gold-dust appearance, all fish must be moved to a separate hospital tank for copper treatment. Display tank stays fishless for 76+ days to break the parasite life cycle.
Bare-bottom 20-40 gallon tank with cycled sponge filter, heater, no carbon, salinity matched to display, temp 76-80°F.
Increase copper concentration over 24-48 hours. Test daily with Hanna or Salifert copper test - copper degrades in saltwater and must be maintained.
Velvet treatment runs longer than ich. Maintain copper for at least 30 days, ideally 35-45.
Without fish hosts, the velvet life cycle dies out. Inverts, coral, and snails are immune. Display continues running normally minus fish.
After 30+ days copper + 1 week off medication observation period without symptoms, drip-acclimate fish back to display parameters and net into the cleared display.
Marine Velvet is preventable in 95%+ of cases by running a 4-6 week quarantine on every new fish before introduction. Read the quarantine protocol.