They are a very fragile fish but can kill fish. How big is the eel? I think a few sevrums would be nice or schooling fish, or you could even do a silver arowana
if it were me i'd get 2-3 pbass and a silver arrow, and maybe an endlichiri congicus, my dream tank though that probably wouldnt work well with a fire eel
I think the aro and 1 pbass will be fine other than that you would need a bigger tank. for the stock you talked about you could do a stock tank which can be bought for like $300 but its basicly just a pond indoors with above viewing only. tractor supply sells them. the biggest is like 8x2 i think