The black triggerfish or black durgon (Melichthys niger), called Humuhumu'ele'ele in Hawaiian, is a blimp-shaped triggerfish with bright white lines running along its dorsal and anal fins. From distance, it appears to be completely black. However, upon closer inspection with good lighting, one can see that it is actually mottled dark-blue/green coloration often with orange toward the front of the head. Black durgons are capable of changing color based on their surroundings. These are not to be confused with their cousins, the Indian triggerfish or black-finned triggerfish (Melichthys indicus), which are often mistaken as being black triggerfish within the aquarium trade. The Indian triggerfish has never been found near Hawaii, but bears a striking resemblance to the black triggerfish because of the similar shape and coloration.
Melichthys niger. Retrieved May, 08 2021, from en.wikipedia.org/wiki/Black_triggerfish.