Causative agent: Gyrodactylus spp. (skin flukes, live-bearing); Dactylogyrus spp. (gill flukes, egg-laying)
Fish flukes — tiny flatworm parasites belonging to the groups Gyrodactylus (skin flukes) and Dactylogyrus (gill flukes) — are among the most common but least visible parasites affecting fish in Australian aquariums. Because they are microscopic and live on or inside the gills and skin, they are frequently overlooked until symptoms become severe. A fish with gill flukes may display rapid, laboured breathing and flare its gills repeatedly; the gills themselves may appear pale, swollen, or covered in mucus. Skin flukes cause persistent flashing and scratching behaviour. Left untreated, gill fluke infestations can lead to rapid death, particularly in discus and goldfish. Praziquantel is the gold standard treatment worldwide and is available in Australia through Aristopet and specialty aquarium suppliers. It is highly effective and relatively safe for the fish. Because flukes are so commonly introduced with new fish purchases, a prophylactic praziquantel treatment during quarantine is strongly recommended by many experienced Australian fishkeepers.
Symptoms
- •Flashing and scratching
- •rapid gill movement
- •excess mucus on body
- •gills appear pale or eaten away
- •labored breathing
- •clamped fins
- •dull colouration
- •sudden unexplained deaths
Treatment
- •Praziquantel (most effective and safest treatment)
- •salt dips
- •formalin baths
- •potassium permanganate dips
- •treat full cycle
Australian Medications
- •Aquasonic Para-Gone
- •Aristopet Fluke & Tapeworm Tablet
- •praziquantel powder via aquarium suppliers or vets
Commonly Affected Fish
- •All freshwater fish
- •goldfish, koi, discus, and most ornamental fish
- •gill flukes common in new imports
Important Notes
Gill flukes are invisible to the naked eye and can kill rapidly. Prophylactic praziquantel treatment during quarantine is highly recommended.