The video shows a large group of fish swimming in a tank. The fish are mostly dark in color, with some lighter colored ones mixed in. They are swimming around in different directions, creating a lively and dynamic scene. The tank appears to be well-maintained, with clear water and no visible debris. The fish seem to be of varying sizes, and some are swimming near the surface while others are deeper in the water. The tank is well-lit, allowing for a clear view of the fish and their movements.