Dave spotted this eel swimming along the surface around the boat hulls. It was a deep, shiny black, with a fan-like tail and two fore fins behind the head. It spent a couple of hours circling one hull but it may have been there longer before we noticed it that morning. After an internet search, we believe this is an American Eel- there is nothing similar in our reef identification guides.
American Eels have a slender, snake-like body covered with mucous (explains why it looked shiny), though it does have small scales. Can be olive, brown or greenish yellow, and those from clear water are generally lighter in colour. American Eels are a freshwater species. Those found in saltwater are migrating to the Sargasso Sea to spawn. Eggs hatch into larvae, then metamorphosise into glass eels, reach freshwater and become yellow eels, and then mature. They are usually nocturnal, feeding mainly on crustaceans and insects. In the past, American Eels were common in many areas between Atlantic Canada and the Gulf of Mexico, but dams and other such structures have affected their migration patterns. This area of the Dominican Republic appear to be on the edge of their range.