Fresh Water Aquariums
Fresh water fish come in a large variety of species, from several different geographical regions. Most aquarium fish originated in Central America, South America, Africa, or Asia. Fish can be kept in different combinations of species and in different kinds of aquatic environments. Four common themes include the community aquarium, the goldfish aquarium, the African cichlid aquarium, and the planted aquarium.
A community aquarium refers to the mixing of fish and plants from different geographical areas with an emphasisis on the color and hardiness of the specimens. An example would be the combination of gouramis, tetras, and rasboras with a selection of hardy plants such as Hygrophila difformis, Hygrophila polysperma, and Vallisneria spiralis. Choosing fish that are peaceful and compatible with each other is important in a community tank.
A goldfish aquarium can be set up as an unfurnished and bare-bottom tank to emphasize the bright coloration of the fish. A combination of different varieties of goldfish and decorations that contrast with the vivid colors of the fish would make an attractive display. Live plants are not usually grown with goldfish, except for hardy, oxygenating plants like Egeria, because goldfish regularly disturb the substrate. They may also feed on softer-leaved plants. Plastic plants can be used instead.
An African cichlid aquarium commonly consists of Lake Tanganyika or Lake Malawi cichlid varieties, and generally requires a large number of rocks combined with a substrate of fine gravel or sand. The rocky environment should provide numerous caves and hiding places. Because cichlids, like goldfish, disturb the substrate by digging, plastic plants should be used as a substitute for live plants. However, real plants like Vallisneria or Anubias can be tried in a cichlid tank.
A planted aquarium emphasizes living plants as much as, or even more than fish. Large groupings of plant species such as Hygrophila, Limnophila, Rotala, Vallisneria, Echinodorus, and Cryptocorynes with a limited number of fish is a good example of a planted tank. It is important to select fish that will not damage the plants, such as small tetras, dwarf gouramis, cherry barbs, zebra danios, and White Clouds. Planted tanks may include CO2 injection and a substrate fortified with laterite or, in the case of a low tech aquarium, a layer of potting soil under the gravel to provide nutrients for the plants.
A biotope aquarium is an aquarium that is designed to simulate a natural habitat, with the fish, plants, and furnishings all representative of a particular place in nature. Because only species that are found together in nature are allowed in a true biotope aquarium, these tanks are more challenging and less common than the other themes. The most common biotope aquariums are the Amazon biotope and the Lake Malawi biotope, but occasionally aquarists will recreate the South East Asia river biotope.