515 ILCS 5/10-40
All individuals taking smelt by any method or with any device, including small mesh nets, shall have a valid sport fishing license.
It shall be lawful to take smelt with a seine, gill net, or dip net. A seine or gill net shall not (1) exceed 12 feet in length, (2) exceed 6 feet in depth, or (3) have a mesh size greater than 1 1/2 inches diagonal stretch. A dip net shall not (1) exceed 12 feet in diameter or (2) have a mesh size less than 1 inch diagonal stretch. No individual shall operate more than one smelt net device at any one time. Individuals taking smelt as authorized by this Section are exempt from obtaining a commercial license. It shall be unlawful to possess any species taken in smelt net devices other than smelt. All fish taken in smelt net devices other than smelt must be returned immediately to the water.
515 ILCS 5/10-40