So many cichlids come to mind-I wish I was in your situation. Availability of a 4"-5" cichlid may be a problem unless you have a specialty shop close by.
Blackbelts get huge (my male was around 16") but other Veijas like bifascatus, hartwegi, zonatus and argentea may work. You might be able to find a nice Geo surinamsis. Maybe a friedrichstahl, motageuse, or losseli
Check out jeff Rapps site hes got the best of the best NW cichlids