Causative agent: Brooklynella hostilis — ciliate protozoan
Brooklynella hostilis is a parasitic disease that holds a special concern for Australian clownfish enthusiasts — this ciliate has a strong preference for clownfish and can devastate a pair within just a few days. The disease causes excessive mucus production, skin sloughing, and rapid breathing, and is often brought into a tank on newly purchased wild-caught clownfish. Brooklynella acts fast and is frequently fatal without prompt treatment. A freshwater dip, where the affected fish is transferred briefly into pH and temperature-matched freshwater, can provide immediate relief by causing the parasites to burst from the osmotic shock. This is then followed by a course of formalin-based medication in a hospital tank. In Australia, Seachem ParaGuard is the most accessible over-the-counter treatment. The best defence against Brooklynella remains a strict quarantine protocol for all new clownfish, ideally for four to six weeks in a separate system before introduction to the main display.
Symptoms
- •Excess mucus on skin
- •skin sloughing or peeling
- •labored breathing
- •loss of appetite
- •fish hangs near water surface
- •similar appearance to marine velvet
Treatment
- •Freshwater dip (5–10 minutes)
- •formalin-based treatments
- •Seachem ParaGuard
- •Aquarium Solutions ICH-X
- •remove to hospital tank
Australian Medications
- •Seachem ParaGuard (available in Australia)
- •formalin baths via aquarium suppliers
Commonly Affected Fish
- •Clownfish primarily
- •other marine fish can also be affected
Important Notes
Particularly dangerous to clownfish. Acts rapidly — treat same day symptoms are observed.