I have a 135 gal. with a flowerhorn an a RT in it what eel would be a good tankmate and just a bad ass addition for my tank.
an aba aba is a horrible idea. as the owner of an aba I would NEVER put it with a FH... or a RT... imo your tank is not going to co-habitat much else if anything and if the RT and FH don't pair off you will have aggression issues eventually. and Cichlids and spiney eels are a huge NO NO... true eels (which are fairly uncommon) don't seem to do well with territorial tank-mates, just slightly aggressive ones.. and there is a big difference in aggression vs territorial.