I would think they'd like brine shrimp (frozen, or you could set up a hatchery yourself) and frozen bloodworms. Actually... I haven't owned a fish yet that didn't love frozen bloodworms, haha.
They will all love bloodworm frozen (thawed) or live and daphinia too. feed as a treat once or twice a week. [EDIT: That darned mandi beat me to it and yes as mandi said brine shrimp ]