A mangrove snapper is another common name for the gray snapper (Lutjanus griseus), a western Atlantic reef fish also called mango or black snapper. According to the Florida Fish and Wildlife Conservation Commission (FWC), adults are typically dark brown or gray with red-orange spots in bars along the sides, and the species commonly reaches about 24 inches and 10 pounds.
Juveniles often use mangroves, seagrass beds, and other nearshore structure (and may enter fresh water); adults favor coastal reefs and similar structure and feed on crustaceans and small fish. Spawning in Florida waters is generally June through August. Source: Florida Fish and Wildlife Conservation Commission — Gray Snapper profile.