Interpet Blue Moonlight 24W T5 aquarium bulb simulates moonlight lighting conditions for your fish and plant life. This bulb is UVA and Actinic meaning it is excellent for fluorescing corals and plant life. This bulb measures 22 inches (560mm). For use in marine aquariums (Use with Tropical Daylight and Reef Daylight Lights) Wattage: 24 Fitting: T5 Length: 22 inches (560mm) Use: Marine Aquariums in tandem with tropical daylight bulbs.