OP - I don't think your metae is one for two reasons. 1) it's missing the dark streak that goes down from behind the eye to the rear of the mouth and 2) it's missing the extension of the midlateral botch up towards the dorsal fin.
For those same reasons, don't think it's a diadema or sp. Jenar Herrera or patricki. That said I'm not quite sure what it might be either. Yellow acara is also the common name for Bujurquina vittata ... but the midlateral stripe doesn't curve up into the dorsal fin instead of the tail fin, so Bujuruina is out.
It might just need to grow out more. Sorry if I made it more confusing.