theres a brand, Formula 1, i believe aquamart sells it, but some other places do. its frozen cubed food... but the best part is that it sinks to the bottom and just sits. nothing needed. i got a copper band that my roommate bought to eat that within a week of being in the tank (little 1.5-2inch max guy)... just let it thaw about 5 minutes, stick it in the tank and shake it around to get what has thawed off and for others to eat. then let it go and it'll sink down for the CBB