In the ocean, you’re either red - or dead

Red fish are less easily seen in deep water

source: New Scientist February 9 2002 p23

Fish at levels of below 20 metres under the surface of the ocean are less visible to predators when they are red, while fish close to the surface are less visible if they are blue. Researcher, Sonke Jonsen, from North Carolina’s Duke University, has developed a mathematical model to show the passage of light in tropical oceans, and his findings are backed by observations that blue fish do indeed tend to be found closer to the surface, while red fish and other red animals are found in deeper ocean water.