Mummichog or common name Mumper

Any one use Mummichog or common name Mumper for fishing.
My son would like to keep them alive a little longer but we just don't know what they eat, water temp, freshwater or add a little salt to the bait bucket? I've seen them been sold in boxes with damp sea weed .
Would like to put them in a 10gal tank an use them when we go out again when he needs them.

they dont need food! if your using as bait. dont feed em. but maybe regular fish food. brine shrimp(since they are wild) stuff along the lines of natural food instead of flakes

Since they eat insects...how about ants.

My son likes to get a pint of mumpers an will last him a couple of weeks if we can keep them alive that long ,they are more hardy than a shiners.