Discus (IMAGE) University of Maryland Caption A Discus (Symphysodon discus), one of three Amazonian cichlid fish species found to be visually adapted to the red-shifted light conditions of the Amazon basin. Credit Wikimedia Commons/<a target="_blank"href="https://commons.wikimedia.org/wiki/File:Symphysodon_discus_04.jpg">Doronenko</a> Usage Restrictions Credit required per Wikimedia Commons license: <a target="_blank"href="https://creativecommons.org/licenses/by/3.0/deed.en">Creative Commons Attribution 3.0 Unported</a> License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.