According to scientists with the National Marine Fisheries Service, gray snapper grow about four inches per year their first two years, three inches per year at age 3-4, and about two inches per year at age 5-6. Most are capable of spawning late in their second year at lengths of about 7.5 inches. Spawning is in late summer, well offshore. Surviving young drift inshore with the tides and settle into grassflat and mangrove habitat. Adult gray snapper look almost exactly like juvenile cubera snappers, except that the cubera has lower canines as large as the uppers, and grows much, much larger.in general, anything over 10 pounds is likely to be a cubera. The color is a gray-green or sometimes bronzish overall, with rusty red edging on the scales. Thereâ€™s a brownish bar over the eyes in young fish. Like all snappers, the mangrove has a tooth patch on the roof of the mouth in addition to the canines; any fish that heads down the gullet is not going to get away.