The video shows a fish tank with a blue shark and a crab. The shark is swimming around the tank while the crab is sitting on a rock. The tank is filled with black gravel and there is a piece of wood with green moss on it. The shark is the main focus of the video, and it moves around the tank, occasionally coming close to the crab. The crab remains stationary throughout the video. The lighting in the tank is dim, creating a calm and serene atmosphere.