My daughter has two aquariums - do you know much about them?
I know some.  The obvious is a place to keep aquatic plants and animals.
She has freshwater fish - guppies, angelfish, and even a cichlid.
I used to work at an office that had a large tank with cichlids.  There are about 1650 species of them!
They are so pretty  - but also pretty aggressive - her's is in a small tank by itself.
described, making it one of the largest vertebrate families. New species are discovered annually, and many species remain undescribed. The actual number of species is therefore unknown, with estimates varying between 2,000 and 3,000.
Many cichlids, particularly tilapia, are important food fishes, while others, such as the "Cichla" species, are valued game fish. The family also includes many popular freshwater aquarium fish kept by hobbyists, including the angelfish, oscars, and discus. Cichlids have the largest number of endangered species among vertebrate
water-filled tank in which fish swim about. Small aquariums are kept in the home by hobbyists. There are larger public aquariums in many cities. This kind of aquarium is a building with fish and other aquatic animals in large tanks. A large aquarium may have otters, turtles, dolphins, and other sea animals. Most aquarium tanks also have plants.
An aquarist owns fish or maintains an aquarium, typically constructed of glass or high-strength acrylic. Cuboid aquaria are also known as fish tanks or simply tanks