Because he wants to bring them home and put them in a tank and “see what happens! Native Michigan fish!” (he orders fish from breeders in like Hawaii and Colorado all the time. He is a bit of a fish enthusiast.)
Part of me wants to think ‘why is my dad dragging me out to wallow in the shallows trying to catch minnows’ but most of me is like ‘I’M GONNA CATCH THE MOST MINNOWS OF ANYONE EVER.’
Edit: HE BOUGHT FOUR BUCKETS. Hahahaha how many minnows am I supposed to be catching here?