Answer: A Discus Fish
The aptly named discus fish has a compressed, circular body and is native to tributaries of the Amazon River in South America. Despite their shy demeanor and extreme sensitivity to water quality, discus fish are a popular choice for aquariums because of their mesmerizing, brightly colored markings. Discus fish feed their young through a strange form of nursing; the larvae nibble at a protein-packed mucus secretion on their parents’ skin. This 20x-magnification image of the fish’s scales captured sixth place in Nikon’s 2009 Small World competition.