Improper or insufficient aquarium lighting causes fish stress, lessened activity and coloration, and poor growth and health in fish and invertebrates. The goal of fish tank lights is to replicate the natural conditions of light in natural habitats. Most aquarium fishes need up to 12 hours a day of the appropriate level of daylight, and it's up to you to give them normal days and nights as they don't have any other way to normalize behavioral cycles (like spawning or even feeding).
At AquariumGuys.com, we have reliable aquarium lighting fixtures for every type of habitat, a full range of bulb choices, hoods and canopies to mount your lighting fixtures, and any lighting accessory needed to complete your setup.
For more information to help you plan your aquarium lighting, check out our full length article!