About Chaetodon ocellatus Bloch, 1787
The spotfin butterflyfish (Chaetodon ocellatus) is a species of marine ray-finned butterflyfish belonging to the family Chaetodontidae. This species occurs in the western Atlantic Ocean, including the Gulf of Mexico, and is most common in the Caribbean Sea. Its common name comes from the dark spot located on its dorsal fin. This spot, along with a vertical black bar that runs through the fish's eye, is an adaptation that confuses predators. The vertical black bar fades and disappears as the fish ages, while other black lines on the fish become more noticeable. From July through late October, juvenile spotfin butterflyfish, along with other reef-dwelling tropical fish from the Caribbean Sea, are often carried by the Gulf Stream into Long Island bays. Spotfin butterflyfish are very common in their range, but they are very difficult to keep successfully in home aquariums. Fully grown spotfin butterflyfish reach a length of 6 to 8 inches.