The video shows a large fish swimming in a tank of water. The fish is seen swimming around and then suddenly opens its mouth wide and begins to gulp water. The fish continues to gulp water until it is full, and then it swims away. The water in the tank is clear, and the fish is the only visible creature in the tank. The fish appears to be healthy and is of a significant size. The tank seems to be well-maintained, with no visible debris or algae. The fish's movements are smooth and effortless, indicating that it is comfortable in its environment.