My two keyholes are the bosses of the tank, including a uaru and a geophagus!
My female has much shorter fins than the male. However apparantly females can sometimes have long trailing fins too, so my 'male' may be a female.
They're not spectacular fish but very personable. Its importent they feel secure so a well planting tank and dither fish are good. A stressed keyhole will look mottled and hide.