6b514bce_ter_Fish___Minnesota_Sea_Grant__Symptom
[Parasite] LAMPREY Three species of parasitic lamprey in Minnesota: chestnut and silver from inland lakes and rivers; sea lamprey from Lake Superior. [Type] lamprey [Description] Sucker mouth with horny teeth and rasping tongue used to cut through scales and skin; feed on blood and body fluids. [Edible] Yes [Recommendation] If fish has an open sore, remove the inflamed area; clean fish and prepare as usual [Symptom] 
Attached Eel-like fish, 6- to 25-inches long; OR circular wound or scar ½- to 1-inch diameter
Parasites of Freshwater Fish | Minnesota Sea Grant
Symptom