Latin Name: Gonostomatidae
Geographic Location: Worldwide
Depth: 200-2000 meter
Size: Up to 30 cm

Their name is derived from their bristle-like teeth. The shallowest bristlemouths are often small and transparent species, whereas the deeper dwellers are larger and very dark-colored species. Bristlemouths have a number of green or red light-producing (bioluminescent) photophores aligned along the undersides of their heads or bodies to provide counter-illumination (camouflage) against ambient down-welling light. One remarkable characteristic of Bristlemouths is their numerical dominance over other mid-water fishes by comprising approximately 50-70% of the mid-water fish catches across various parts of the world's oceans. They are even thought to be the most abundant vertebrate on Earth. Daily vertical migration occurs in the shallower species but not the deeper species. Bristlemouth reproduction is though to be seasonal and many species only release eggs at the end of its life (semelparous). Some species are also known to undergo sex-reversal while others have distinct variations between males and females (dimorphism) The stomach contents of some bristlemouths suggest that they chase and feed, then rest and digest. They typically remain imobile in the water while passively awaiting prey.