The Red penguin has already collected 1 Fish token. They take their turn and pass through a door with a Fish token above it, collecting another Fish token. Since they now have 2 Fish tokens, they decide it is a good time to use the Ice Skates. They reveal that they have two Fish cards worth 1 point, place them next to their Reminder card, and takes an extra turn.
In that extra turn, the Red penguin manages to pass through the last door with a Fish token and collects it. Since the Red penguin has collected all of their Fish tokens, the round ends.