15 Interesting Fun Trivias About Swordtail Fishes

Swordtails fishes or scientifically called Xiphophorus hellerii is one of the popular tropical freshwater fishes that is commonly kept as pets in home aquariums or outdoor ponds. It is one of the prettiest aquarium fish and very hardy. It is also one of the top 10 most commonly kept freshwater fishes in the country. They are reasonably priced and they can reproduce fast.


Origins : In the wild, it has an olive green body with red and yellow along the sides and sometimes colorful speckles on its fins. With this coloration, it is most commonly called the Green Swordtail or the Red Swordtail. However, in captivity, it has been bred into the fabulous colors that make it so highly prized today.

15 Interesting Fun Trivias

1.) Xiphophorous means “bearing a sword” and hellerii named for Carl Heller. The species was described by Heckel in 1848. They are found in North and Central America, where they range from the Atlantic slopes of southern Mexico (Rio Nantla, Veracruz) to northwestern Honduras and Belize.

2.) There are about  dozen known species of sword tail fishes. These include the Montezuma Swordtail (Spotted Swordtail) Xiphophorus montezumae, Delicate Swordtail Xiphophorus cortezi, and Mountain Swordtail Xiphophorus nezahualcoyotl. A couple of dwarf species, the Pygmy Swordtail Xiphophorus pygmaeus and Panuco Swordtail Xiphophorus nigrensis.

3.) Originally found It is native to southeastern Mexico, central Guatemala, southern Belize, and northwestern Honduras.

4.) Xiphophorus montezumae was introduced into the aquarium hobby as early as 1864, while the popular Green Swordtail was first introduced in 1909. The Swordtails do well in the water temperatures ranging from 65 to 82 F (18 to 28 C).

5.) Hybrids comes in all form of colors and sizes, but some are not available locally. They are results of meticulous breeding . The colors includes Red, Red Wag, Red Tux, Painted, Neon Green, Marigold (and wag), Black, Red Twin bar, Sunset, Gold Tuxedo. Red Wag, Red Velvet, Marigold, Black Nubian, Pineapple,Red Simpson, Spotted and Gold tux Swordtail

6.) They are almost naturalized in many parts of the world and have established themselves with large feral populations in southern Africa, including Natal, Hawaii, Madagascar and eastern Transvaal in South Africa and Otjikoto Lake in Namibia. Significant populations have also established themselves along the east coast and western part of Australia and New Zealand.

Freshwaterfishgroup.com also have a listing on fish species which are considered invasive.  There is also a study on the University of Western Australia in feral population of green swordtails .

There are also large feral population of these freshwater fishes in southern parts of the United States. USGS listed some of the states which have the feral population.  Mostly from captive fishes which had escaped domestication or discarding unwanted specimens into waterways or escapees from ponds reaching waterways through flooding events.

swordtail fish
double swordtail fish

7.) Males has a bulkier body than either of those two, though, and also has a “sword” extending from the bottom of the male’s tail fin. It is often thought to be named for the “sword” shaped extension of its tail fin, but the swordtail was actually named for the sword-like appearance of the male’s anal fin. This specialized anal fin develops as the male fish matures. The middle rays of the anal fin are modified into a narrow copulatory organ called a gonopodium. There are also double swordtails.

8.) Swordtail is a live-bearer and can give birth to as many as 20 to 200 fry at one time. A spawning box is recommended, or if one is not available, dense floating cover should be provided to protect the fry from the adults. Once sex is determined, the males should be separated because swordtails can begin breeding at as young as three months of age especially in tropical climate.

9.) They produce 2 types of males – a quick maturing long sworded, short lived male that is ready to go at 4-5 months, and a second wave ‘sleeper male” form that looks like a female until it matures at 9 months to a year. The second type of male is not as good looking, but it lives a lot longer.

10.) Number of Fish: Ideal ratio is between 5 to 6 females to 1 male swordtail to balance the harassment from male fish towards the females for breeding. They like moving water with a high mineral content.

11.) It is an omnivore that will eat commercially prepared flaked foods, algae, as well as freeze-dried blood worms, tubifex,  brine shrimps, daphnia, mosquito larvae or vinegar worms as long as it can fit in their mouth.

female swordtail fish
female swordtail fish

12.) If there are no male there are the ability of the females can change their sex. Female is larger with robust body which reaches up to 16 cm in length while the male is somewhat smaller and can grow up to 14 cm in length. Female produces between 15 to 200 fries after a gestation period of 24 to 30 days. This species has a tendency to undergo sex reversal under certain environmental conditions. It can live up to 5 years or more with proper care.

13.) Ideal tank mates include: Guppies, Platies, Mollies, Tetras, Rasboras, Gouramis, Rainbowfish, Danios, Angelfish, Plecos and Scavenger Catfish.

14.) Bureau of Fisheries and Aquatic Resources ( BFAR) encourages backyard tropical fish farming to augment income for small scale and medium growers.

15.) There are no formal association in the country which specializes in swordtail fishes, normally they are group together with livebrearer fishes like guppies, mollies and platty. There is Philippine Arawana Lou Han Society( PALHS) which had an active forum .

Bibliographies and References:

Scott, Peter. R. Interpet 2000, An Interpret Guide to Livebearing Fishes

  • McDowall, R. M., 1996. Livebearers. In Freshwater Fishes of south-eastern Australia, (Ed. R. M. DcDowall), Reed Books, NSW. pp. 116-122.
  • Wischnath, Lothar, 1993 , Atlas of Levebearers of the World.
  • Axelrod, Herbert R, Wischnath, Lothar .1991 Swordtails and Platies.
Rence Chan

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