The term CORAL REEF DWELLER can be summarized as an EEL, which is a three-letter word. Eels are elongated fish that inhabit marine and freshwater environments. They are found in tropical and temperate waters around the world, and many species live in coral reefs. Eels have a slimy skin and can range in size from a few inches to several feet long. They feed on small fish, crustaceans, and other invertebrates.