If you live near the sea (like I do) you can collect as many bait fish as you like. Some like minnows will live well in a small tank, others like baby bluefish, which are very common will only live a few minutes in a bucket. I feed these animals including sandworms, crabs, shrimp, seaweed, snails, sponge, mussels, and amphipods every day in the summer. I even strain the mud under rocks for copepods and dump that in. Since I am lucky to have access to this stuff I would never buy frozen food in the summer. I always believed live is better. When I used to keep frogfish and ran out of food I would inject guppies with cod liver oil to feed the frogfish, of course, live saltwater fish is much better.
Paul
Paul