In the video, there is a large fish swimming in a tank. The fish has a long body and is brown in color. It is swimming near the bottom of the tank, where there are two other fish. One of the fish is lying on its side, and the other is swimming near the surface of the water. The tank appears to be well-lit, and the water is clear. The fish are moving slowly and gracefully, and there is no visible aggression or interaction between them. The tank seems to be a controlled environment, possibly a home or a public aquarium.