What are the three basic types of aquarium?

* The three basic types of aquarium are freshwater, saltwater fish-only and marine live coral reef. Freshwater aquariums may be further divided into those with artificial plants and those with live plants. Saltwater aquariums are divided into fish-only tanks where only fish (and possibly hermit crabs) are kept and live coral reefs which house living corals and invertebrates in addition to fish species which do not prey on corals or invertebrates. Saltwater reef aquariums and freshwater live plant aquariums are sometimes called "balanced ecology" aquaria, as their ecosystems are more complete and typically have fewer problems.