Lakes in Grand Teton National Park: Six (6) trout* per day or in possession, no more than three (3) shall be cutthroat trout; and no more than one (1) cutthroat trout shall exceed twelve (12) inces. Fishing - Grand Teton National Park (U.S. National Park Service) Any fish an angler chooses to to release must be carefully and immediately returned to the water from which it was taken.