
Black Durgon
Sep15, 2017. Seen in the dive site Sharon's Serenity in Bonaire.
These triggerfishes are quite shy and they were mostly at the limit of the coral drop off and rather deep, 25m o more.
interestingly in the link below is mentioned that they may feed on feces and vomits of cetaceans (..remarkable..).
http://www.fishbase.org/summary/Melichthys-niger.html

The black triggerfish or black durgon , called ''Humuhumu'ele'ele'' in Hawaiian, is a blimp-shaped triggerfish with bright white lines running along its dorsal and anal fins. From a 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.