An aquarium system includes a tank, a motion sensor, and a light source. The motion sensor is adapted to sense motion within a predetermined distance from the tank. The light source has a controllable intensity projecting light into the tank. The intensity varies responsive to motion sensed by the motion sensor. When the motion sensor senses movement, the light is on at 100% intensity. After some period of no-motion, such as about 60 seconds, the lighting slowly dims to around 20% of full brightness. When it senses movement again, the lighting slowly ramps up to 100% intensity.