The video shows a group of koi fish swimming in a dark pond or tank. The fish are of various colors, including white, red, orange, and yellow. They are densely packed together and seem to be near the surface of the water, with their mouths occasionally opening as if they are feeding or seeking food. The water is slightly turbulent, causing ripples and bubbles. The fish move around each other in a crowded fashion. There are no people visible in the video, and the focus is solely on the fish and their interaction in the water.