I am sure you have never heard of this fish. If you can imagine such a thing this fish known as the bristlemouth is a bit smaller than the average human finger. The fish has a mouth full of fangs and it can glow in the dark. To me, it sounds like a fish from outer space. This fish also has the most common vertebrate in the world. Bristlemouths have the ability to increase in number up to the hundreds of trillions.