Freshwater Angelfish (IMAGE) University of Maryland Caption A freshwater Angelfish (Pterophyllum scalare), 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:Pterophyllum_scalare_-_%22Rio_Nanay%22_-_souche_sauvage_-_Aqua_Porte_Dor%C3%A9e_06.JPG">Loury Cedric</a> Usage Restrictions Credit required as per Wikimedia Commons license: <a target="_blank"href="https://creativecommons.org/licenses/by-sa/4.0/deed.en">Creative Commons Attribution-Share Alike 4.0 International</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.