Parasitic
🔴 Fatal
🔔 OIE Notifiable
✓ Treatable
Gyrodactylus salaris (Monogenean Fluke)
🦠 Gyrodactylus salaris · Gyrodactylidae (Monogenea)
📋 Definition
A monogenean ectoparasite devastating to naive Atlantic Salmon populations, causing hyperinfection and near-complete mortality of parr in rivers where it is introduced.
📊 Key Facts
Causative Agent
Gyrodactylus salaris
Agent Family
Gyrodactylidae (Monogenea)
Geographic Range
Introduced to Norway (devastating), also found in Sweden, Russia, Finland
Transmission Routes
Direct fish-to-fish contact, water currents
Primary Host
Atlantic Salmon parr (naive populations)
Vaccine
✗ None / Experimental
Economic Impact
Destroyed wild Atlantic salmon populations in 40+ Norwegian rivers
🩺 Clinical Signs
Rapid multiplication on skin causing mucus hyperproduction, osmotic stress, fin erosion, lethargy and death of salmon parr.
🔬 Symptoms
🔬
Excessive mucus production
Integumentary Subacute
🔬
Fin erosion
Integumentary Subacute
🔬
Lethargy in parr
Systemic Chronic
🧪 Diagnosis
Wet mount of skin scraping — characteristic opisthaptor anchors.
💊 Treatment
Rotenone (river treatment to eliminate infected fish), aluminium salts (lower pH barrier), diversion of salmon migration.
🛡️ Prevention
ℹ️ Prevention is the most effective strategy for managing this disease in aquaculture and aquarium settings.
Strict biosecurity on movement of live fish and equipment between river systems.