How big is it, was it wild caught or captive bred? All I can say is that it looks like a juvenile, so somewhere around a few months. But feedings, tankmates, cleaning routine, water parameters/temp, and many other factors can all alter growth rate, making it impossible to judge merely off of size. Only way to know for sure would be contacting its breeder (if he or she remembers/knows about this particular one’s age/when it’s parents bred). Jexnell duanes
Deadeye hit the nail right on the head. We can't say an age due to the many variables.
Size is a more important variable. At the 3 to 4in range they mature and can start breeding. Most larger CA cichlids function this way.
Age plays a bigger role in some fish such as Oscars that don't mature till 1.5 years old.
Here is an example of how hard it would be to determine age based on size.
The two midas in the pictures are siblings from the same batch but the two toned one was a slow grower, not quite a runt of the batch but noticeably smaller than its brother. Both are the same age.