I tried it with a lungfish and it worked - but the poor lungfish would get shocked, so I ended that after a week. Other than that, didn't try anything else.
I keep mine with tilapia. I had hundreds from an unwanted spawning so chucked most of them in with my puddles, he ate alot but there's still 10 or so with him there reaching 7" now and puddles the eel is 32"