This fish is the plainfin midshipman (Porichthys notatus). If you were looking at the top of the fish, you would see a plain grayish fish with a rather large mouth. One of the midshipman's interesting features actually lie underneath the fish. These interesting dots on the underside of the fish are photophores, which can produce a bright light pattern. Its still not clear what the light is for, but some speculate that the midshipman uses them to lure prey closer when hunting. The midshipman will hang in the water column and flash its light to attract prey items.
Interesting thing number 2 is how midshipman reproduce. Like most fish, males are responsible for maintaining the nest and attracting the females to lay their eggs. Male midshipman will hum for hours on end to attract females to their nest. The hum is produced by the fish vibrating their swim bladder, and can be so loud that people walking on a beach can hear it (and people living on boats often find it hard to sleep). Female midshipman who are producing eggs (more estrogen) are more sensitive to the humming noise and more likely to seek out its source .
Here's a nice news article on the midshipman's love life, with some sound bytes attached (for Quicktime viewers only).