Geophagus will do good but are more bottom dwellers like the Lima's, so I'd go for something else like Metynnis or Myleus species (middle swimmers). Another option could be some peacefull cichlids like Acarichtys and Uaru.
lol yea thats why i said middle and top swimmers, but geos are still nice fish even if they are on the bottom. i like a lot of the ray and geo mixes ive seen in the past
i have uaru amps and fernandies with my ray and no problems.
you could also ad a dat, my geos swim all over the place and occupy the same level as my uarus
i agree arauna and dats are nice , cichlids might pick at the ray. cause stress. Ive kept large cichlids and it sucks when a 4 dollar jack dempsey kills something expensive like synspellum or a black belt cichid. or something more valuable.