The practice of sorting fish is illegal. Sorting is the release of one fish in order to keep a larger fish of the same species to stay within the daily catch limit for that species. Tagged and Marked Fish Anyone interested in marking or tagging fish in public water must get approval from the Division of Fish and Wildlife before marking or tagging begins. An application, available from the Division of Fish and Wildlife, must be processed 21 days before the scheduled start date. An approved permit must be carried by the permit holder when fish are being marked and tagged.
Fisheries biologists attach external tags or mark fish using finclips for research projects.
Please report all tags to a district fisheries biologist. At some waters, voluntary tag return boxes have been installed. Provide the biologist with the type of fish caught, the length, date, location, weight of fish and the tag number. If a tagged fish is released, the tag should be reported but left in the fish in good condition. Some fish, such as paddlefish on the Ohio River and trout and salmon on Lake Michigan and its tributaries, have internal tags about the size of a hyphen on this page.