Fish are interesting.

For instance, they have no external ears but have internal ones found deep within their brain cases.

They can make noises: croaks, cackles, squawks and purrs. Fish see in color. Rings on the scales of a fish tell its age just like rings in a tree trunk.

Fish form the largest group of animals with backbones, with at least 20,000 species. More than 160 species of fish live in Minnesota waters.

In North America, the codfish family has but one kind of strictly freshwater cod, the eelpout (aka burbot).

As is typical of codfish, it has a large, oily liver. The liver oil is a remarkable fluid rich in vitamins A and D and even has healing properties when applied to sores. The eelpout can be found in northern Minnesota lakes and rivers, including Lake Superior. Their tiny scales, long top and bottom fins, and spotted body makes identification easy. Their food consists of other fish but also fish eggs, clams, crayfish, mayfly larvae and other aquatic insects. Usually adults are less than 8 pounds and less than 28 inches long. The Minnesota state record is 19 pounds, 3 ounces; it was caught in Lake of the Woods. Eelpout are most active in winter, their spawning time. They are sometimes caught by anglers fishing for walleyes. Dropping your bait within inches of a deep muddy river or lake bottom such as the mud flats in Lake Mille Lacs has a chance at eelpout.

Unfortunately, the festival devoted to the fish, on Leech Lake’s Walker Bay, was canceled this year (organizers wrote on Facebook that “the economics no longer work.”) Those in the know say that eelpout, now classified as a game fish, are good eating, on a par with northern pike and walleye when baked, fried or boiled.

Jim Gilbert’s observations have been part of the Minnesota Weatherguide Environment Calendars since 1977, and he is the author of five books on nature in Minnesota. He taught and worked as a naturalist for 50 years.