''Poecilia velifera'', known as the Yucatan molly and also as the giant sailfin molly amongst aquarists, is a very large

Livebearer Livebearers are aquarium fish that retain the eggs inside the body and give birth to live, free-swimming young. Among aquarium fish, livebearers are nearly all members of the family Poeciliidae and include guppies, mollies, platies and swordtails ...

that lives in coastal waters of the Yucatan peninsula. These live-bearer (

Poeciliidae The Poeciliidae are a family of freshwater fishes of the order Cyprinodontiformes, the tooth-carps, and include well-known live-bearing aquarium fish, such as the guppy, molly, platy, and swordtail. The original distribution of the family was t ...

)

fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of li ...

are particularly well known for both the extreme size variation among males, and the sexual dimorphism between males and females in both body shape and behavior. It is outwardly similar to the

sailfin molly The sailfin molly (''Poecilia latipinna'') is a species of fish of the genus ''Poecilia''. They inhabit fresh, brackish, salt, and coastal waters from North Carolina to Texas and the Yucatán Peninsula of Mexico. Taxonomy The sailfin molly was o ...

, ''P. latipinna'', though larger overall and with a higher and longer

dorsal fin A dorsal fin is a fin located on the back of most marine and freshwater vertebrates within various taxa of the animal kingdom. Many species of animals possessing dorsal fins are not particularly closely related to each other, though through conv ...

in males. Full-grown fish are usually larger than 10 cm (4 in) and large females can reach almost twice this length, though especially captive-bred individuals grow only to the size of sailfin mollies. The dorsal fins are the most distinctive character for telling the

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

apart: Those of the Yucatan molly have nearly 20

fin ray Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as see ...

s, counting where the fin meets the back, whereas the sailfin molly has less than 15 (intermediate numbers may indicate hybrids). If the males spread their dorsal fins in display, these have a distinct fan or

trapezoid A quadrilateral with at least one pair of parallel sides is called a trapezoid () in American and Canadian English. In British and other forms of English, it is called a trapezium (). A trapezoid is necessarily a Convex polygon, convex quadri ...

shape, with the upper edge being distinctly longer than the lower. The height of the dorsal fin, measured at the posterior edge, is a bit larger than the height of the tail.

Common names

Some names of the Yucatan molly - such as ''Segelkärpfling'' or the specific name ''velifera'' - contain an element signifying "sail", aggravating the confusion with the sailfin molly. The French terms are used for both species indiscriminately, as is the Japanese name (which is simply the Japanized form of "sailfin molly"). *

Dutch Dutch commonly refers to: * Something of, from, or related to the Netherlands * Dutch people () * Dutch language () Dutch may also refer to: Places * Dutch, West Virginia, a community in the United States * Pennsylvania Dutch Country People E ...

: ''Hoogvinkarper'' *English: Yucatan molly, sailfin molly (though this name is often used for ''

Poecilia latipinna ''Poecilia'' is a genus of fishes in the family Poeciliidae of the order Cyprinodontiformes. These livebearers are native to fresh, brackish water, brackish and salt water in the Americas, and some species in the genus are euryhaline. A few have ...

'' as well as the commercially produced hybrids kept by fishkeepers) *French: ''Molliénésie á voilure'' or simply "molly voile" *German: ''Segelkärpfling'' *Japanese: セイルフィンモーリー (''seirufuin mōrī'') *Polish: ''Molinezja żaglopłetwa'' *Portuguese: ''Molinésia velífera'' *Russian: Моллинезия Велифера, Широкоплавничная моллинезия *Dansk: Sejlfinnemolly *Thai: plā sel fi nyạks̄ʹ̒ (ปลาเซลฟินยักษ์; literally: "giant sailfin") *"Korean": 자이언트 세일핀 몰리 ("Giant sailfim molly) *Indonesian : Cere Laut

In the aquarium

Especially small strains are suitable for keeping in an

aquarium An aquarium (plural: ''aquariums'' or ''aquaria'') is a vivarium of any size having at least one transparent side in which aquatic plants or animals are kept and displayed. Fishkeepers use aquaria to keep fish, invertebrates, amphibians, aq ...

. However, this fish is not as easy to keep as the sailfin molly, let alone the ''P. sphenops'' (

black molly ''Poecilia sphenops'' is a species of fish, of the genus ''Poecilia'', known under the common name molly; to distinguish it from its congeners, it is sometimes called short-finned molly or common molly. They inhabit fresh water streams and coas ...

). They need spacious tanks with well-aerated, slightly

brackish Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estuari ...

teaspoon A teaspoon (tsp.) is an item of cutlery. It is a small spoon that can be used to stir a cup of tea or coffee, or as a tool for Cooking measures, measuring volume. The size of teaspoons ranges from about . For cooking purposes and dosing of med ...

to 1

tablespoon A tablespoon (tbsp. , Tbsp. , Tb. , or T.) is a large spoon. In many English-speaking regions, the term now refers to a large spoon used for serving; however, in some regions, it is the largest type of spoon used for eating. By extension, the ter ...

sea salt Sea salt is salt that is produced by the evaporation of seawater. It is used as a seasoning in foods, cooking, cosmetics and for preserving food. It is also called bay salt, solar salt, or simply salt. Like mined rock salt, production of sea sa ...

per 10

liter The litre (international spelling) or liter (American English spelling) (SI symbols L and l, other symbol used: ℓ) is a metric unit of volume. It is equal to 1 cubic decimetre (dm3), 1000 cubic centimetres (cm3) or 0.001 cubic metre (m3). ...

s with the higher amount being suitable for wild strains, the lower for color variants. Note that many popular freshwater fish - such as

tetra Terrestrial Trunked Radio (TETRA; formerly known as Trans-European Trunked Radio), a European standard for a trunked radio system, is a professional mobile radio and two-way transceiver specification. TETRA was specifically designed for use by go ...

s and

danionin The danionins are a group of small, minnow-type fish belonging to the family Cyprinidae. Members of this group are mostly in the genera ''Danio'', ''Devario'', and ''Rasbora''._They_are_primarily_native_to_the_s_...''._They_are_primarily_native_t ...

s - will become sick and may die in brackish water. water to thrive. They are able to withstand higher temperatures than most pet fish. Although they can survive over 30 °C for prolonged periods of time if other conditions are good, temperatures should be kept between 25 and 30 °C. Direct sunlight and an ample supply of plant food, such as lettuce, peas, or certain

algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mic ...

, are necessary for optimal health; in

subtropical The subtropical zones or subtropics are geographical zone, geographical and Köppen climate classification, climate zones to the Northern Hemisphere, north and Southern Hemisphere, south of the tropics. Geographically part of the Geographical z ...

areas, they can be kept outside in unheated tanks in the summer; in temperate zones, backup heating may be necessary.They are

euryhaline Euryhaline organisms are able to adapt to a wide range of salinities. An example of a euryhaline fish is the molly (''Poecilia sphenops'') which can live in fresh water, brackish water, or salt water. The green crab (''Carcinus maenas'') is an e ...

species. This strain of molly can also be kept in saltwater reef tanks, and provide clean-up duties for the tank. To transition a molly to saltwater, adjustment time is needed; increase the salt content to match the reef tank over a period of three hours. They are bred like other mollies; in line with their general requirements, this is somewhat more difficult than in related species. It is especially hard to get males to grow their spectacular fins. Professional breeders often separate males and females in winter, so that they are eager to breed in spring. Young can then, climate permitting, grow in spacious outdoor basins during summer. Like other ''

Poecilia ''Poecilia'' is a genus of fishes in the family Poeciliidae of the order Cyprinodontiformes. These livebearers are native to fresh, brackish and salt water in the Americas, and some species in the genus are euryhaline. A few have adapted to livin ...

'', they are prone to

hybridization Hybridization (or hybridisation) may refer to: *Hybridization (biology), the process of combining different varieties of organisms to create a hybrid *Orbital hybridization, in chemistry, the mixing of atomic orbitals into new hybrid orbitals *Nu ...

with their relatives. Not infrequently, crosses are attempted with the sailfin molly to breed a hardier fish. This is generally not very successful, and should not be attempted, as purebred Yucatan mollies are often quite hard to find, and hybrids will not have as massive dorsal fins as these. Several color variants are also available; these usually do not attain the large size of wild-type fish and may have been crossbred with ''P. latipinna''.

Reminder

External links

{{Taxonbar, from=Q923248 velifera Fish described in 1914 Freshwater fish of Mexico Live-bearing fish Ovoviviparous fish Taxa named by Charles Tate Regan