When I go into my LFS I see a huge array of frozen foods for fish. Among them are:
Beefheart, Bloodworms, Daphnia, Krill, Mussel, Mysis Shrimp, Plankton, Reef Plankton, Sand Eels, Silversides, Squid, White Mosquito Larvae.
Along with several kinds of Brine Shrimp:
Baby Brine Shrimp, Brine...