You can also feed your fish small live insects found around the house and garden. Aphids are commonly found on roses and are relished by most fish. Small flies and mosquitoes make good food but must be free of pesticide. If you accidentally leave a bucket of water sitting outside in the shade, and some leaves drop into the bucket of water, chances are mozzie larvae will appear in it and they can be scooped out with a fine mesh net, rinsed and fed to any fish.
Wingless fruit flies are available from most universities and lab supply companies and can be easily cultured and fed to the fish.
If you find live daphnia, you can grow that outdoors in a tub of green water. It makes a great food for any fish less than 5 inches long. And if you get a surplus of daphnia, mozzie larvae or aphids, you can freeze them for use later on.