Weiss: Seek small-stream serenity when larger waters are crowded for trout opener The 2021 Minnesota trout opener is set for next Saturday, April 17. Anglers can legally begin keeping fish an hour before sunrise that day. Written By: John Weiss | × Larry Haugen tries to keep a lot profile while fishing a small Fillmore County stream. He enjoys the smaller streams because they often offer excellent fishing. (John Weiss / sports@postbulletin.com) Really? Larry Haugen stopped his car by what appeared to be a large trickle of water winding along a remote Fillmore Count road. Obviously too small, too insignificant for trout fishing. What trout angler would bother?