Poecilia velifera
Encyclopedia
Poecilia velifera, the Yucatan molly, lives in coastal waters of the Yucatan peninsula
. These live-bearer (Poeciliidae
) fish
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
, P. latipinna, though larger overall and with a higher and longer dorsal fin
in males. Full-grown fish are usually larger than 10 cm (4 in), 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
apart: Those of the Yucatan molly have nearly 20 fin rays, 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
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.
. However, this fish is not as easy to keep as the sailfin molly, let alone the P. sphenops (black molly). They need spacious tanks with well-aerated, slightly brackish
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
, are necessary for optimal health; in subtropical areas, they can be kept outside in unheated tanks in the summer; in temperate zones, backup heating may be necessary. 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
, they are prone to hybridization 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.
Yucatán Peninsula
The Yucatán Peninsula, in southeastern Mexico, separates the Caribbean Sea from the Gulf of Mexico, with the northern coastline on the Yucatán Channel...
. These live-bearer (Poeciliidae
Poeciliidae
Poeciliidae is a family of fresh-water fish which are live-bearing aquarium fish . They belong to the order Cyprinodontiformes, tooth-carps, and include well-known aquarium fish such as the guppy, molly, platy, and swordtail...
) fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate 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...
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
Sailfin molly
The sailfin molly, Poecilia latipinna, is a species of fish, of the genus Poecilia. They inhabit fresh, brackish, and coastal waters from North Carolina to Texas and the Yucatán Peninsula of Mexico.- Taxonomy :...
, P. latipinna, though larger overall and with a higher and longer dorsal fin
Dorsal fin
A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...
in males. Full-grown fish are usually larger than 10 cm (4 in), 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
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
apart: Those of the Yucatan molly have nearly 20 fin rays, 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
Trapezoid
In Euclidean geometry, a convex quadrilateral with one pair of parallel sides is referred to as a trapezoid in American English and as a trapezium in English outside North America. A trapezoid with vertices ABCD is denoted...
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").- DutchDutch languageDutch is a West Germanic language and the native language of the majority of the population of the Netherlands, Belgium, and Suriname, the three member states of the Dutch Language Union. Most speakers live in the European Union, where it is a first language for about 23 million and a second...
: Hoogvinkarper - English: Yucatan molly, sailfin molly (though this name is often used for Poecilia latipinna as well as the commercially produced hybrids kept by fishkeepersFishkeepingFishkeeping is a popular hobby concerned with keeping fish in a home aquarium or garden pond. There is also a fishkeeping industry, as a branch of agriculture.-Types of fishkeeping systems:...
) - 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
In the aquarium
Especially small strains are suitable for keeping in an aquariumAquarium
An aquarium is a vivarium consisting of at least one transparent side in which water-dwelling plants or animals are kept. Fishkeepers use aquaria to keep fish, invertebrates, amphibians, marine mammals, turtles, and aquatic plants...
. However, this fish is not as easy to keep as the sailfin molly, let alone the P. sphenops (black molly). They need spacious tanks with well-aerated, slightly brackish
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
Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...
, are necessary for optimal health; in subtropical areas, they can be kept outside in unheated tanks in the summer; in temperate zones, backup heating may be necessary. 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
Poecilia is a genus of euryhaline brackish water fish in family Poeciliidae of order Cyprinodontiformes. The type species is P. vivipara. Live-bearers, the Poecilia species are collectively known as mollies, with the exception of Endler's livebearer and the famous guppy...
, they are prone to hybridization 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.