You got the answer. Females are blue. Males are blue till they start to mature. Keep him in a tank with quite a number of other fish and with plenty of rocks. Can be quite an aggressive fish.
I am only having one problem with this ID of this fish..when i got it ..it was only an inch and a half and it was yellow just like it is now..should it have been blue at that age?Or is it not all of them that have this color variation.. did yours have it Red kid?