A fishing light attractor is an underwater light that can be used to attract fish of many species, including baitfish, and larger fish. It really depends on the type of water (fresh or saline) to determine the species. These lights produce a lot of heat, which is why they do so well as fish attractors.
It is also known as a Green Light, or Green Fishing Light. It is called that because of the hue that it gives off, and the color of light that reaches the surface of the water.
Use of such lights for catching fish is unlawful in some jurisdictions, but is perfectly legal in others. It is not only used for catching fish, but can also be an aesthetic way to have a natural aquarium in your backyard waterway.