In the video, a person is seen using a blue toothbrush to clean a fish tank. The person is scrubbing the sides of the tank with the toothbrush, moving it back and forth to remove any dirt or algae. The tank appears to be made of glass and has a wooden stick inside it. The person's hand is visible as they hold the toothbrush, and the water in the tank is clear, indicating that the cleaning process is effective. The video provides a close-up view of the cleaning process, allowing viewers to see the details of the tank and the cleaning action.