Many shallow reef inhabitants and fish have the capabilities to detect fluorescent light and may be using biofluorescence in similar fashions to how animals use bioluminescence, such as to find mates and to camouflage

Biofluorescence occurs when an organism absorbs electromagnetic radiation at a specific wavelength and then, subsequently, transforms this energy and emits it at a longer, lower energy wavelength.

Many marine fish dwell in spectrally restricted domains of low light intensity. At great depths, the red, orange, yellow and green components of sunlight are removed. The authors explain that this leaves a very narrow band of blue light, between a wavelength of 470 and 480 nanometers, resulting in an environment that is spectrally restricted when compared to terrestrial environments. Therefore, this presents a novel opportunity for organisms to harness the powers of biofluorescence.

http://guardianlv.com/2014/01/biofluorescent-fish-widespread-according-to-study/