Whatever the size tank, I would always go Channa, but yeah, U.S. don't like my plans.
I can think of a few Crenicicla species that would work, those are pretty fun fishes with a lot of character that you don't see everywhere.
It's hard to find fishes for a volume I'm not used to, I would say an Erythrinus Erythrinus as you mentioned wolves, that one would definitely fit the tank size, though I can't vouch for your Eel's well being long term. My Ery Ery tried to chew up on a Gymnothorax, killed it, and decided he didn't want to eat it. So he got exiled to his species tank until I free up the 180g where I'll attempt comming him again.
You could also go the Exodon Paradoxus route, but be prepared to rehouse the eel. Watching a big shoal of Exodons is pretty amazing, and if the shoal size is good enough (might take a few months with a student's budget), you shouldn't have too much losses.