Steady spread of weatherfish in Chicago area: Does it mean anything?

By Dale Bowman

Rich Anzalone photographed an unknown fish in a pond near Lemont at the end of May. He sent the photo to Vic Santucci, the head of Illinois’ Lake Michigan Program. He forwarded it to Phil Willink, a senior research biologist for the Shedd Aquarium.

It was a weatherfish. Odd fish end up in our waters all the time, unfortunately. Weatherfish are more than that.

‘‘Weatherfish are more common than people realize in the Chicago waterways,’’ Willink said. ‘‘They are very much flying under the radar. They are relatively small, and they live along the bottoms and are pretty secretive.’’

He said most are about 6 inches, though they can reach a foot, the size of the one Anzalone photographed.

Map of the spread of weatherfish around Chicago.<br>Credit: From John Thomas Belcik’s masters thesis for Loyola University — Map of the spread of weatherfish around Chicago.
Credit: From John Thomas Belcik’s masters thesis for Loyola University

The first record of a weatherfish in the Chicago area was in 1987 in the North Shore Channel. They spread southward to the Sanitary and Ship Canal, then back through the Cal-Sag and into the upper Illinois River.

‘‘They are used to this climate, apparently,’’ Willink said.

Part of the reason they fly under the radar is because they live on the bottom, even in the muck, and it is tricky to find them. Chicago waterways in general drop straight down. Unless specifically sampling for them, they rarely would be found.

The group surveying regularly for Asian carp bump into them most often.

‘‘I don’t know anyone else who comes across them very often,’’ Willink said.

They are a southeast Asian fish, though there is some question about species. As to where they live in their natives lands, Willink said, ‘‘Meandering rivers, backwaters, rice paddies, that type of habitat.’’

Willink said the name came because they are sensitive to weather changes and ‘‘supposedly wiggle around and do these weird dances before storms. I have not seen it.’’ He said they ‘‘do have the hardware to detect pressure changes.’’

Willink said their secretive nature on the bottom is one reason he doesn’t know any fisherman who has caught one.

‘‘I have seen pictures over the years,’’ he said. ‘‘Most records are of people looking down and seeing them and taking a picture.’’

They’re also spreading in the United States.

‘‘They popped up in New York, Idaho, Michigan and probably other places,’’ Willink said. ‘‘They keep spreading.’’

He finds them an interesting fish with an incredible versatility. They sometimes use air to breathe, so they can survive if a pond dries out.

‘‘I’ve gotten them in puddles,’’ he said. ‘‘I surveyed a stream that had dried up into pools. There were still weatherfish [living] in the pools.’’

They don’t like open water or current, so Willink said it isn’t likely you’ll find them in the Kankakee River or in Lake Michigan, which has too much sand and is too exposed.

Willink worked with two master’s students on things such as DNA, food and habitat.

‘‘When they started popping up in wetlands in the lower Des Plaines, then people started paying more attention,’’ he said.

There is some concern that they might eat sensitive species of aquatic insects in the wetlands.

‘‘We don’t have evidence that it is directly competing with anything,’’ Willink said. ‘‘Maybe with white suckers, but they hold their own.’’

Even after 30 years, Willink said: ‘‘Still trying to figure out if they are going to have an impact.’’

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