ST. PAUL, Minn. (AP) - University researchers say a parasite is attacking fish in Minnesota and Wisconsin.

Nick Phelps' team at the University of Minnesota is trying to learn more about the parasite, which dissolves the muscles of fish. He says 26 lakes are known to have been infected in Minnesota since 1990, with 15 species affected.

Phelps says it's a nasty disease, and yellow perch are some of the most commonly affected fish. He says the parasite basically destroys the filet, so you wouldn't want to eat it. Fortunately, people aren't known to be susceptible to this disease.

The parasite is called Heterosporis. Infected fish have the appearance of freezer burn.

Phelps says it's not clear how it's spreading or how prevalent it is. Fish in 16 Wisconsin lakes have also been affected.