An aquarium pump is a device used to circulate water in an aquarium, ensuring that it remains clean and oxygenated. It helps maintain a healthy environment for fish and other aquatic life by moving water through filters, which remove debris and toxins. There are different types of aquarium pumps, including submersible pumps and external pumps. Submersible pumps are placed underwater, while external pumps are located outside the tank. Both types play a crucial role in maintaining water quality and supporting the overall ecosystem within the aquarium.