The video shows a group of fish swimming in a tank. The fish are of different colors and sizes, and they are all swimming around a red ball that is hanging from a string. The fish seem to be playing with the ball, as they swim around it and try to bite it. The tank is well-lit, and the water is clear, allowing for a good view of the fish and the ball. The fish are moving quickly, and their fins and tails are visible as they swim. The red ball is the only object in the tank, and it stands out against the blue background of the water.