Quick referenceSkin + gill flukes (Dactylogyrus + Gyrodactylus) are monogenean parasites that attach to gills + skin. Cause flashing + breathing distress. Treat with praziquantel (PraziPro).
Symptoms
Scratching/flashing
Rapid breathing
Excess slime coat
Cloudy eye(s)
Refusing food
Color fade
Pale or discolored gills
Cause
Monogenean parasites attach to gills (Dactylogyrus, egg-laying) or skin (Gyrodactylus, livebearing). Spread via fish-to-fish contact or contaminated water. Common entry: pet-store stock.
Treatment options
Praziquantel (PraziPro). Gold-standard treatment. 1 tsp per 20 gal. Single dose; repeat in 7-14 days for Dactylogyrus eggs. Reef-safe (won't harm corals).
Formalin bath. Backup. 45-min bath at 1 tsp per gallon. Use for fish that don't respond to prazi.
Salt bath. 5-10 min in 3% salt solution kills flukes on skin. Limited effect on gill flukes.
Always treat in a separate quarantine or hospital tank. Most medications are toxic to coral, invertebrates, and live rock biology. Consult an aquatic veterinarian for valuable fish.
Prevention
Quarantine new fish 30 days + dose prazi prophylactically. Avoid mixing tanks with shared nets.
Fatality + outcome
Low to moderate. Heavy infestations kill via gill damage + secondary bacterial infection. Light infestations are tolerable but stressful.