Skin flukes (<i>Gyrodactylus salaris </i>)


Fish constantly rubs or scratches itself against any object available.
Abnormal swimming - streaks
Fish swims in short bursts, then stops.
Pale slime film over skin
A slimy thin grey/white film covers the body.
Abnormal swimming - flashing.
Sudden bursts of speed with rolling motion.
Faded colours
Colour of body has a washed out look.
Fins frayed or ragged
Fins look as if they are rotting away, giving eroded appearance.
Haemorrhages - skin
Bloody haemorrhages are apparent over several parts of the skin.
Listless and lethargic
Fish moves very lazily in water, much less than normal, lacks interest.
Skin excessive sliminess
Skin shows mucous and slime far in excess of normal.
Sluggish movements
Fish moves almost reluctantly in the water.
Reluctant to feed
Fish comes to eat but with evident lack of appetite.
Grey/blue tone of skin
Skin colour is a grey/blue tone.
Loss of membrane & rays
Fins are eaten away, both the rays & the interstitial membranes between
Sits on bottom
Fish sits still in upright position, on the bottom of tank or pond.
Faded colours
Colours of fish look washed out compared to normal.
Ulcers - circular
Ulcer with circular shape.
Whirling or tumbling
Fish fall down in a spiral or "head-over-heels" fashion.
Bare rays
All interstitial tissue on fins has been eaten away.


Gill and skin flukes of the genus Gyrodactylus. Worldwide distribution and a broad range of hosts. These parasites are small worms with a hook at the end of the body and are vivaparous. Found on skin, sometimes on gills. Size is .5-.8mm.


Early detection and treatment is a must. Correct treatment will completly cure. Please note that parasites leave immediately the body of a dead fish, so examination must be made on living specimens.


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DNA and RNA diagnostic references

Taxonomy and systematics of Gyrodactylus salaris ( Monogenea, Gyrodactylidae) infecting wild populations of Arctic charr ( Salvelinus alpinus ) in Norway

From Department of Zoology Natural History Museum University  Oslo Norway  2005

Cand. scient. thesis in Zoology by Grethe Robertsen. 

Note:- Excellent and exhaustive treatment of the DNA for this important parasite. 


Dr. Mo, Tor Atle
Central Veterinary Laboratory

Oslo Norway


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