I kept a fire eel for about 8 years, got him at @ 7inches never had him eat anything other than earth worms he would however taste and spit out live foods, but when he would see the earthworm container come out of the fridge he would dance at the surface making slurping sounds and when given the worms would slurp them up like a child with spaghetti, a 55 gallon was fine for years and the eventual upgrade to a 90 was not necessary but didn't hurt. when these eels get used to you( and it doesn't take long) they'll do things like wrap themselves around your wrist while you rearange the tank, in every way a wonderful aquatic friend definitely more than just a fish