Fish cannot see ultraviolet B rays, but still change their behavior when they grow up under increased UVB intensity. According to studies by biologists at the University of Bonn on three-spined sticklebacks (Gasterosteus aculeatus), increased UVB leads to a smaller body size and more risk-seeking behavior when faced with predators. Climate change is likely to increase UVB intensity, possibly with consequences for ecosystems and fish farming. The results are now being published in Biology Letters.