How long can i keep a red devil cichlid in a 50 gallon?

For those who have a iPhone you can see the picture I uploaded but my red devil is and 2 inches and he or she is in a 50 gallon how long do I have before I have to upgrade or do i even need to upgrade and to what size… And can by looking at the picture can anyone tell me the sex and age of my fish…

Kisss