Transport of fish for display in a home aquarium is legal under the following
conditions:
Game fish purchased from an authorized licensee transported with the
necessary documents (such as a sales receipt).
Anglers 16 or under may transport legally caught largemouth bass,
smallmouth bass, yellow perch, rock bass, black crappie, white crappie,
bluegill, pumpkinseed, green sunfish, orangespotted sunfish, and
black, yellow, and brown bullhead. No more than four of each species
may be transported at any one time, and any individual fish can be no
longer than 10 inches. At no time may water from infested waters be
transported. (See DNR Web site)
http://files.dnr.state.mn.us/rlp/regulations/fishing/fishing2009.pdf