Not sure if all shiner species act the same, but my spotfin shiners still are eager for feed even in cold temps. They don't attack it with gusto like in the dog days of summer, but the optimal feed in the BG JR size will bring them in anytime there is open water. We have had a strange winter with a couple blizzards but rapid thaws and most of Dec and Jan so far little ice or no ice on the pond. Of course this winter I don't have any more optimal on hand but it would be ideal to keep them fed all winter. I love how they seem to truly be a 4 season fish in my pond.