My three fire eels have NO interest in fish. They get hand fed, so I'm guessing a big reason is they are lazy bums. But, I've had feeders in there before, and the eels seem more irritated by them than anything. If you can keep them off feeders its probably better. My guys used to get blood worms, but then graduated to red wrigglers and then night crawlers (both earthworms). They also get krill, chunks of market shrimp, and tilapia. My biggest guy, Norbert, won't even eat off the ground. Unless I hand it to him, he won't eat it. But, no complaints. I love that fat, lazy, princess of an eel.