Its a Satanoperca of some kind, one of the eartheater types I would guess its Satanoperca Leucostica. Very nice fish but quite delicate, he will also need a sand substrate as he gets bigger as they will sift the sand through their gills all day long and if the gravel is too big it can damage their mouths but if its not quite small enough it gets stuck in their gills which causes quite a lot of issues.
Whats your set up like at the moment, tank size, tank mates, how long has it been up and running?
Wills