I actually keep my brine shrimp alive as long as I can, I then can normally then feed them to my Mollies/Swordtails/Guppies. So I give them a little water change, add salt and feed them very fine powdered food. Got one **** of a fright after leaving it a few weeks and then seeing this fully grown brine shrimp swimming about lol. Made good snacks for the fish in the community tank though!
Saw a guy on youtube who actually just leaves the leftover in a bucket outside and fishes out brine shrimp whenever he needs to feed his fish.