These shy fish live back in dark holes and caves on the seaward reef. They are not especially rare, but usually it requires use of a flashlght to see one, and once you do, the fish tends to ease back out of sight before you have a chance to aim the camera. The upper photo was taken by Jay Lord at Kwajalein. These are reported to grow to about 200mm in length, which would be quite a lot larger then the biggest we have seen..
The photo below was taken at Bayu in Bali and shows the long pelvic fins that give this family the common name of "longfins."
Created 11 July 2018