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The cyprinid family contains around 1,300 species, widely distributed on most continents of the world. They inhabit all types of waters and adapt readily to various water conditions.

The body shape is conventional, with symmetrical contours, but it may be slender or quite deep, depending on habitat. Cyprinids have seven fins: two sets of paired fins and three single ones. Pharyngeal teeth in the throat grind food before it reaches the intestine. The arrangement of these teeth provides positive identification between similar species.

Coldwater cyprinids include the most popular aquarium fishes of all, the Goldfishes and Koi. Tropical cyprinids are divided into three main groups: barbs, which are like miniature carp, inhabit the middle and lower water levels; danios are faster swimming and prefer the upper levels; and rasboras use all water levels. All cyprinids spawn using egg scattering methods and do not usually exercise parental care.

Tropical cyprinids

Barbs, danios, and rasboras are the most common tropical cyprinids. These attractive smaller cyprinids from both tropical and subtropical waters are undemanding in the aquarium and easy to feed. </noinclude>


African and Asian barbs have been sold in the aquarium trade for many years. Wild stocks of some species such as Barbus titteua (cherry barb) from Sri Lanka are very low, but the species is still widely available in the hobby, due to captive breeding. The majority of the small barbs are bred by the thousand in fish farms in the Far East, South Africa, eastern Europe, and Florida. Captive-bred fishes are easier to transport and not as sensitive to changes in water conditions as wild fishes, and so are easier to acclimatize.

Barbs are found in all bodies of water, from streams and rivers to lakes, and are shoaling fishes. Applying this to the aquarium, when purchasing fishes you should get a group of six to ten, more if you have room. A sparsely planted aquarium is ideal as this allows plenty of swimming space in the mid to lower levels. With the exception of Barbus tetrazona (tiger barb), most small barbs are compatible with equal sized fishes in the community aquarium. Tiger barbs are noted for their quarrelsome nature, but even this can be overcome provided they are kept as a shoal of eight or more in a large aquarium, when, as they are so busy chasing each other, they leave the other fishes alone. Only if kept in smaller numbers do they really cause any trouble.

With some of the medium sized species, keep the aquarium well covered as they may jump, especially if chasing around at feeding time. </noinclude>


Danios are fish native to the fresh water rivers and streams of southeast Asia. Many species are brightly colored, and are available as aquarium fish worldwide. Danios are very similar to barbs but are much slimmer-bodied. They are found in large shoals in fast flowing waters. In the aquarium they prefer the upper layers of water and may be seen cruising around all day. They are peaceful, ideal community fishes.

They are insectivores and their upturned mouth is ideally suited to taking insects from the water surface. They are not fussy about food and will take flakes and frozen fish foods without any hesitation. Bred by the thousand in commercial fish farms, albino and long-finned strains of Brachydanio rerio (Zebra Danio) and Brachydanio albolineatus (Pearl Danio) have been developed. These strains are not quite as hardy as the wild type and require slightly higher temperatures. </noinclude>


This group of fishes is one that is, by and large, overlooked by most aquarists, and yet there are a fair number of them in the trade. Inhabiting both still and running water, large shoals can be seen near the surface. They are found in southeast Asia and the Indo-Australian archipelago. In the main they are insectivores, but will take flake foods. Give them a varied diet, especially if you are going to attempt to breed them, and include small live foods or frozen Daphnia and similar-sized items.

Rasboras can be divided into two groups by body shape; those which are long and slim, almost torpedo-shaped, and those which are deeper-bodied. </noinclude>

Other cyprinids

Barbs, Danios, and Rasboras form the largest groups of tropical cyprinids, but are not the only ones. This section deals with the smaller groups, including the sharks and flying foxes. These fish are from a variety of climes, and each requires special water conditions. </noinclude>

Coldwater cyprinids

Single-tailed Goldfish

Goldfishes have been kept in captivity longer than any other fishes, and many varieties developed from the one original species, Carassius auratis, remain popular. This section is devoted to single-tailed varieties - hardy fishes that can over-winter outdoors. Their cultivation is generally limited to developing exaggerated fins and various color strains.

Twin-tailed Goldfish

These goldfishes are termed "twintails" because their causal and anal fins hang in double folds. Their aquarium-bred bodies become truncated and egg-shaped, and the ability to swim is gradually impaired as the form changes from the natural streamlined shape. These restrictions mean that twintails are not suited to outdoor ponds. They could not compete in a race for food, nor flee from predators. Their delicate fins may also become congested in inferior water conditions. The maximum size of a twin-tailed goldfish attains depends on the size of the tank in which it is kept.

Koi are ornamental domesticated varieties of the common carp. Despite their long term unsuitability for the indoor aquarium, there are many aquarium-bred strains of the ornamental Koi (Cyprinus carpio) and a selection is shown here. It is customary to view and judge these dish from above, and their colors and patterns have been developed accordingly. Koi originated in east Asia, but strains are now cultivated worldwide.

Despite being titled "Monotypic", this article is about any Coldwater cyprinid that does not fall neatly into another group </noinclude>

Other coldwater cyprinids

Many fish-keepers' coldwater interests center around Goldfish and Koi, but there are other attractions in this field of the hobby. In spite of their relative obscurity, it is easy to keep different North American fishes, such as shiners and sunfish, as well as bitterlings and some species from Asia.


  • Rogers, Geoff, 1994- Focus on freshwater aquarium fish
  • Bailey, Mary, 1999- The ultimate encyclopedia of aquarium fish & fish care

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