I feed my eels a combination of uncooked shrimp and a seafood combo that I buy from the local supermarket. The seafood combo is an uncooked combination of squid, shrimp, cuttlefish, and a few other items and is sold in 1 pound packages. I have been feeding my eels this for many years. You may have to look around for it since I have only found it at select supermarkets.
Some of the other fish enjoy this as well, particularly the larger carnivores like triigers, lions, and rabbit fish..