Generally you can easily distinguish between male and female especially at that size, but there are exceptions to every rule especially when it comes to Festae. If your fish is a male, he is exhibiting typical female coloration minus the spangling. I have seen males this color, but it's typically when they are paired up with a female. I have yet to see an unpaired male exhibiting female dress. As for spangling, from a batch of 8 juvies, I grew 2 females out to 11.5 and 12". They both retained their spangling until they were successfully paired up with males and then the spangling vanished. They also exhibited the same finnage as yours. Until that time I swore I had 2 males. Different strains are able to produce males that can mimic females. And on rare occasions females that can mimic the spangling associated in males. Out of curiosity, who'd you get him from?
Been raising/breeding FESTAE since 1978. My best guess on your festae is male, but based on past experience, can't be 100% certain. I am certain of this, yours ain't no Uro(false festae). LOL!