Aquarium Definition – What is an Aquarium?

An aquarium is a terrarium or water-filled tank in which fish and other aquatic plants or animals may be kept and displayed. Aquariums may be either freshwater or saltwater and they are popular as a home hobby, with many enthusiasts having collections of varying sizes. In some cases, large public aquariums are maintained for viewing or educational purposes.

The term “aquarium” is also applied to virtual aquariums, which are computer programs that use 3D graphics technology to display a virtual underwater world on the screen of a desktop or laptop computer. These are typically used as screen savers, though some also serve as software applications that allow users to interact with the animated world on their screens in real-time.

Aquariums are often constructed from glass or high-strength acrylic and range in size from a small bowl, several liters in volume, to massive public aquariums containing thousands of gallons. Regardless of size, aquariums require special equipment to maintain appropriate water quality and other characteristics suitable for their inhabitants. Typical aquarium equipment includes filters that remove waste and other pollutants, water heaters to regulate temperature, oxygenators to increase oxygen levels in the water, and heaters or coolers to control water and air temperature.

In addition to the aforementioned equipment, an aquarium requires specialized care to maintain its inhabitants. A key challenge is managing the nitrogen cycle. Animal and plant waste releases ammonia, which if not metabolized by the inhabitants can be toxic to them. To prevent this, the aquarium is filled with organisms able to break down these waste products. These organisms are called bacteria, and they ingest the ammonia through the process of nitrification.

Other nutrient cycles also play an important role in the health of the aquarium. Dissolved oxygen enters the system from air or via an aquarium aeration device, carbon dioxide exits the system to the atmosphere, and nutrients such as iron, phosphate, and sulfur cycle through the system, entering as food and leaving as waste. Appropriate handling of the nitrogen cycle and careful consideration of biological loading, which is the rate at which organisms excrete waste, can be sufficient to maintain these other nutrient cycles in approximate equilibrium.

A fundamental aspect of aquarium design is the interrelationship between the different parts of the ecosystem. For example, the green plants in an aquarium remove nitrogen from the water and release oxygen, and the animal life in the tank uses oxygen and expels carbon dioxide. In an ideal aquarium, these processes are well balanced, resulting in the creation of an environment in which the inhabitants are both happy and healthy.