Not trying to be mean here but kind of hard to guestimate an age when we don't even know how big the fish is. The lab looks pretty small but it could also just be a big tank. Got a rough size estimate? Btw even with a size estimate it's still just going to be a guess on the age.
Ik I have 2 female FH's and both are the same age from the same parents but do to different Gene's the one is at 8in while the other is at 5in. So even with both being the same age, same gender and from the same parents they still vary quite a bit in size just do to different genetics they got from each parent.
Try to get a better pictures showing more of the fish, looks young so it will be hard to tell, when it gets bigger it would get easier to tell the gender.