Murky Amazon waters cloud fish vision

African cichlid fish evolved in calm, clearwater lakes saturated with sunlight, and are known for their incredible visual system, which relies on a diverse array of visual pigment proteins called opsins. A new analysis is the first to examine related cichlids from the murky, silty water of South America’s Amazon Basin. The researchers found that, in three select Amazonian species, several opsin genes had been switched off or lost entirely.