According to nerds at Oregon State University Sea Grant Extension, this strange phenomenon is the natural byproduct of bacteria that makes certain marine life act like an incandescent light bulb. But take that with a grain of salt, because salt added to the seafood during processing will make a non-lethal dose of bacteria grow quickly at normal refrigerator temperatures.
One ray of light in that revelation: If you're in the middle of a blackout, your flashlight isn't working and you have no candles, pull a tiger shrimp out of the fridge, stick it on a skewer and use it like a tiki torch until power is restored.
Can Godzilla be far behind?