But why do lantern fish light up? According to Maxime Geoffroy, a fisheries researcher scientist at the Marine Institute in St. John's, the reasons are not fully understood. The fish might be communicating with each other to signal danger lurking in the depths, he said. "We know they produce light when they are stressed. So that's one hint that it's probably a reaction to predation or to fear.… The bioluminescence is being used to camouflage so their predators have trouble seeing them," said Geoffroy.