Black durgon by Gérard Cachon Via Flickr: In some dive sites black durgons are relatively common. They tend to school and they propel themselves like other triggerfish, moving their dorsal and anal fins. Very fun to watch. They have no trouble being a bit distant from you, but they are annoyingly hard to get into close range. Even if you approach carefully, and don't blow bubbles, they move quickly to just a bit too far for an image. Although they usually just look black underwater, if you are lucky to get close and with the right light, you can see that they have an array of colors. Hit them with strobe light and the magic of their pattern really emerges. To me, the most interesting thing about the pattern is that it is not the same throughout the fish - there are several regions with the pattern blending at the boundaries. Not sure if that gives them an evolutionary advantage - if you know why the pattern shifts, please let us know in the comments.
