Maybe some cats and plecos. parrots might add some color if the arrow will leave them alone. Salvini could hold his own in there too. Just throwing out some ideas
Definately the Prochilotis as a cleaner. i have 2 and theyre the best. passive but resiliant and clean clean clean all day long. If you have access to Oxydoras Niger that would be an awesome bottom feeder.
Get a Tigrinus or a Juruense. Nice beautiful cats, not too big and not too aggresive. I have kept them with Aro and cichlids. No problems at all. Can be trained to take most foods with ease!