United States

Rare in the hobby, the bowfin is a stunning specimen fish for the aquarist with the means to house it properly. It is the sole remaining species in the family Amiidae, an ancient and primitive group that is related to the garfish. It possesses the ability to breathe atmospheric air, via an enormous, highly vascularised accessory breathing organ that extends throughout the entire body cavity. The gills are stiffened in order to prevent them collapsing outside the water and, provided it's kep...

While the surface-dwelling form of this species is fairly unremarkable and rarely-seen in the hobby, the blind form is very popular indeed. The two may have diverged as recently as within the last 10,000 years, with the blind form losing its eyes and much of its pigment. This probably happened because the fish needed better development in other sensory areas. Losing unnecessary and energy-consuming aspects of its physiology allowed it to devote more energy to developments such as increased numbers of taste receptors on the head.

Contrary to many reports, including a number of scientific papers, this species breeds in the same way as other cyprinodontids and does not dig pits or exhibit extended parental care. It's a fractional spawner with females depositing eggs on a more-or-less continuous basis when a warm temperature is maintained though ideally it should be permitted to breed on a seasonal basis in spring and late summer as it would in nature.

This species has been a popular aquarium fish for a considerable period and virtually all fish traded are now raised commercially for the purpose. It is easily identified by the characteristic bright red or orange underside of the head, which is more pronounced in adults. Following Miller and Taylor (1984), the genus Thorichthys is identified...

X. cancila is often seen referred to as 'freshwater garfish', and although it does superficially resemble the true gars of the family Lepisosteidae, it's actually a member of the Belonidae, or needlefishes, the majority of which are marine or estuarine in existence. There are currently just two species in the genus although the probable existence of a third member has been noted by Roberts (1989) among oth...

Wild swordtails are a fairly basic green colur. However the vast majority of swordtails available in the hobby today are hybrids of X.helleri with X.maculatus or X.variatus. There are a huge number of selectively-bred varieties available, including wagtail, lyretail, tuxedo, albino, neon, red, green and hi-fin. Swordtails may undergo what appears to be a change in sex. In young fish this may simply be late development. However some adult females develop male characteristics which is thought ...

This is one of the largest freshwater fish species in the world, and clearly shouldn't be considered a home aquarium subject at all given its eventual size and the fact it can live for well in excess of 50 years. We include it here only because some public aquaria are able to maintain it long-term. Unfortunately, juveniles are seen for sale quite regularly in the aquari...

This species is largely unsuitable for the home aquarium given its eventual size and natural behaviour, and we know of only a handful of private aquarists with the facilities required to house it long-term. It's currently illegal to import or own the species in the United States, United Kingdom and several other countries unless in possession of an official license.

Despite being a wholly unsuitable aquarium subject, C. idella is often traded as such, with an albino form having been developed specifically for the ornamental market. Individuals which have outgrown their aquarium or pond should never be released into natural waters, either, since this species has proven capable of causing serious environmental damage under a wide range of climatic conditions.

This species is not a common aquarium species but is occasionally available from specialist retailers or breeders. It was initially named Adinia multifasciata by Girard (1859) before later being redescribed as Fundulus xenicus (mispelled 'Fundnlus') by Jordan and Gilbert (1882). Body stout and trapezoidal in adults, body depth usually 2 to 3 times in standard length; scales large, fewer than 30 scales along midlateral scale row...

Also known as the mosquito fish, least killifish or dwarf top minnow, H. formosa is the smallest known livebearing fish species, and one of the smallest overall fish species in the world. It's not often seen for sale these days, although it's quite widely available in hobbyist circles. When buying these, ensure they have been identified correctly as they're sometimes confused with the much more aggressive mosquito fish of the genus Gambusia....

Known from Great Lakes Erie and Michigan with distribution extending south through the Mississippi River basin to the Gulf of Mexico drainages where it's said to occur between the lower Apalachicola River in Florida and the Nueces River in Texas. It may also be found in the Rio Grande which forms the border between Mexico and the United States further south where records include Falcon International Reservoir, for example.

Tends to be most common in brackish to hypersaline environments such as coastal salt marshes, lagoons and estuaries. On San Salvador Island, Bahamas, it appears to be the parent of a species group occurring in sympatry and exploiting diverse but specific resources with some spectacular morphological adaptations.

This species is frequently confused with C. argus but can be distinguished by the following characters: dorsal-fin rays 38-45 (vs. 47-50 in C. argus); anal fin rays 26-29 (vs. 31-36); lateral line scales 50-56 (vs. 60-66); 2-3 rounded blotches on caudal peduncle (vs. no blotches on caudal peduncle). It is widely-distributed in Pacific coastal drainages of southeastern China (e.g. the Yangtze, Minjiang, Hangjiang River, and Pearl (Nanjiu...