Why do some rotting fish glow in the dark

In some parts of the world, one of the simplest tests of whether meat or fish has gone rotten is to look for the emission of light. The test for healthy flesh is to ask the question, Does it glow If the flesh does display a ghostly glow then it is luminescent, and contains biochemical organisms that are hazardous to health. 

Bioluminescence results from a chemical reaction, so it is more strictly termed chemiluminescence. Biochemical energy is converted directly to radiant energy. The process is virtually 100 per cent efficient, so remarkably little heat is generated during emission. For this reason the emission is often called cold light , or luminescence. 

This form of luminescence occurs sporadically in a wide range of natural organisms, such as protists (bacteria, fungi), animals, marine invertebrates and fish. It even exists naturally, albeit rarely, in plants or in amphibians, reptiles, birds, or mammals. 

One of the names of the devil in the Hebrew Bible is Lucifer, and comes from a Hebrew word meaning light bearer.  

Luciferin is one of the simplest examples of chemiluminescence, and it is remarkably efficient. The overall yield is one photon per molecule of luciferin. 

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