The video shows an aquarium with a blue shark and a crab. The shark is swimming around the tank, while the crab is hiding in a cave. The tank is decorated with rocks and plants, creating a natural underwater environment. The shark appears to be a model, as it moves smoothly and without any signs of struggle. The crab is mostly stationary, with its claws tucked under its body. The water in the tank is clear, and there are no other visible creatures or objects.