I would never put an eel in with a pair of cichlids I was trying to breed, espicially cubans...
Fire eel can go with BGK, dats,bichirs, rays, geophagus....just wondering now if what kind of eel would you put in a 125 with something not cichlid
best kind of eel for a 125 would be in saltwater...nice display tank for a dragon moray or one of the other horned morays...wouldn't bother with dull, reclusive, passive freshwater eels
A 125 would not be big enough for a fire eel. The largest eel you could get for a tank that size would probably be a Mastacembelis dayi, or possibly an M. favus. And I also disagree with the dat and ray suggestions. Dats eventually need about 240 gallons minimum (although they are slow growers), and rays need a footprint of at least 6' x 3' (or larger, depending on the species).