Cichlid (Green Terror) behavior

Question
I have a Green Terror (alone) in a 20 gallon tank... the fish is about 5" long, and has rather "showy" fins and markings... the tips of the dorsal fin extends well beyond the tip of the tail, ending in a long, slender / tapered point, the tips fo the fins are briliant orange... so I made the assumption I had a male Green Terror. The question is regarding "his" behavior.. He arranges the aquarium the way he likes it... and he does this continuously. He picks up rocks, oyster shells, large barnacles, etc. (in his mouth) and moves them to the side or wherever he wants them... He also appears to be clearing out what appears to be a nest (or bed as we used to call them when I was a kid fishing for Bream in Georgia).

Along with this landscaping - he seems to go through what could be called "aggressive spasms", in which he shakes his head back and forth, darting about the aquarium as if "he's not alone"... and he'll suddenly stop to move a rock or shell into the "right spot". He appears to either be threatening his own reflection in the aquarium glass, or perhaps exhibiting spawning behavior with his reflection?

He seems quite healthy, appetite and appearance are just fine... Any insight is very much appreciated!

THANK YOU!!!

Answer
Hi Tom,
  In the world of a male cichlid, hope springs eternal.  While you and I know that no female is going to appear in that tank, he thinks that it just might happen and if she does appear, he is ready!   

-- Ron
  rcoleman@cichlidresearch.com
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