The video shows a fish tank with a light shining through it. The light changes colors and patterns, creating a mesmerizing effect. The fish in the tank swim around, occasionally coming into view. The colors of the light shift from blue to green to red, and the patterns change from solid colors to stripes. The fish tank appears to be well-maintained, with clear water and no visible debris. The fish are of various sizes and colors, and they move around the tank in different directions. The light source seems to be positioned in such a way that it illuminates the entire tank, highlighting the fish and the decorations within.