In the video, a man is seen holding a small device in front of a large fish tank. The man appears to be using the device to clean the glass of the tank. The fish tank is filled with various types of fish and aquatic plants, creating a vibrant underwater scene. The man's movements are deliberate and careful, ensuring that he cleans the entire surface of the glass without disturbing the fish. The lighting in the room is dim, allowing the colors of the fish and plants to stand out against the dark background. Overall, the video provides a glimpse into the maintenance of a large fish tank, showcasing the importance of cleanliness and care in creating a healthy environment for the fish.