Can you keep a flathead catfish in Michigan?

15 inches, five a day.

DNR source page

What we left out on purpose

• Lake sturgeon runs its own separate regulations table (harvest tags, very limited season, in most waters catch-and-release only) that eRegulations references but does not print inline on the general regulations page. Not modelled here rather than guessed.
• Smelt (2 gallons per person per day statewide) is dip-netted or seined rather than rod-and-reel targeted, and is left out for the same reason baitfish species are excluded elsewhere in this silo.
• Michigan's dozens of named-lake exceptions for northern pike (protected slots, relaxed size rules) and muskellunge (46-to-50-inch broodstock lakes) are not modelled beyond the two waters this site actually reports on — the same restraint used for Colorado's Gold Medal waters and Kansas's named-reservoir exceptions.
• The Walleye possession limit specific to Lake Erie/Detroit River/Lake St. Clair/St. Clair River is carried as unsettled because the source's own text shows a limit that should have already been updated for the current season (see reviewNote) — check DNR directly rather than trust a number here.