Common Aquarium Livebearers
Swordtails:
This splendid fish came from East Central Mexico. They are
scientifically named as Xiphophorus helleri. Wild swordtails and their
direct descendants are green with a red stripe running from the nose to
the top edge of the long sword of male. From these wild
types a number of true breeding color varieties from cross breeding have
been derived. With these are Red Swords, Tuxedo, Gold, Red or Gold
Wagtails, Berlin and the Simpson Hi-fins in a variety of colours. The
purpose of the sword on the males appears to be of aid in his being
recognised by the female during courtship.
A less frequently seen, shorter Swordtail is X. Montezuma, also from
Mexico. This gray-green fish is not as lively or hardy as the helleri
Sword.
Platies:
This is probably the most popular aquarium fish. Its name came from its
former tongue-twisting scientific name Platypoecilus maculatus. The name
has changed in recognition of its close biological relationships to
Swordtails, to Xiphophorus maculates. Tank-raised Platies Afton had a
crescent mark near the tail and because of this are still called Moons
by old-timers. Like their relative species Swordtails, Platies have been
established in a tremendous array of true breeding colour forms. These
are essentially color forms as found in Swordtails, examples are
Wagtails, Tuxedos, Reds, Golds, etc. The Platy ranges from Mexico to
Guatemala.
Variegated Platy:
This Platy is also from Eastern Mexico, named scientifically Xiphophorus
variatus. Wild variatus males have combination of reds, yellows and
black, as the principal tail colour or may have yellow and red. They also
vary in colors and markings. There are several true breeding varieties
that have been developed; together with them are Yellow-tailed,
Marigold, Sunset, Red-tailed, Tuxedo and most recently, Hi-fin
varieties. The Hi-fin is still quite expensive, reflecting the time and
thorough work required in developing the strain.
Guppy:
This is a well-known aquarium fish that almost everyone knew it. Its
common name refers to Englishman, Lechmere Guppy, who was responsible
for bringing it to the attention of scientists. The wild Guppy male is a
short-finned very active fish attractively blotched with
green, red and black spots. It is virtually impossible to acquire wild
type of Guppies in a shop. The female is much bigger than the male and
shows his beautiful finnage and coloration. In fact they look like
female Swordtails. Few strains are developed with colour on the tail.
This lack of color is sex limited; meaning, the potentiality for colour
is present in the female but it does not show. Feeding the male sex
hormone (testosterone) to the female will make her colour up. As the use
of the hormone is discontinued, the colour fades.
Mollies:
The black molly has been bred from the wild green Molly (Mollienesia
latipinna) which arises in brackish waters of southern States south to
Venezuela. Black ones rarely happen in wild fish but from such rare
specimens Florida fish breeders developed the all black species. They
are called Black Mollies even by non-English speaking aquarist from
Europe. They do best in hard, alkaline water with two teaspoonfuls per
gallon of non-iodized salt. They need spinach or algae in their diet,
and prefer temperatures of 27 degrees Celsius. Male Mollies raised in
aquarium have smaller dorsals compared to pond-raised fish. The
scientific name for mollies is set to be changed to Poecilia, as is that
of Guppy, in acknowledgement of its close relationship to that fish.
Black Mollies generally available in shops are probably crosses between
black latipinna and velifera.
Mosquito fish:
There are two types of livebearers called Mosquito fish. From Sothern
New Jersey to Florida and Texas, the Gambusia affinis is called Mosquito
fish because it has been distributed widely throughout the globe as a
mosquito eater. It is an outstanding hardy fish but has few to recommend
it as an introduction to fish-keeping. It is aggressive and bites at
other species, tearing up their fins. It doesn't have pretty colours.
Both sexes are colored like wild kind of female Guppy. Occasionally,
they are partially black spots in nature. A marbled
black Gambusia was readily available before the black Mollies were
recognised in the hobby.
Heterandria Formosa is another Mosquito fish originated from North
Carolina to Florida. Its popular name was got from its size. It is
nearly the world's smallest livebearer and smallest vertebrae animal.
This brownish fish is a great aquarium fish. A pair in a 7.5 litres,
well-planted aquarium will produce young soon; a few of them will avoid
being eaten. A population of these little fish will become well-known
and can be maintained for years on dry food and occasional meals of baby
brine shrimp. Females produce two or three young per day over an age of
about a week.
Half-beaks:
A Dermogenys pusillus, is the only aquarium livebearer not belonging to
the family Poeciliidae. The (Hemiramphidae) Halfbeak family has various
kinds of marine, fresh- water and brackish south eastern Asiatic
Halfbeaks, of which Dermogenys is the smallest measuring about 2-3
inches (5.5 - 7.5. cm). Halfbeaks are not very colorful, it only has a steel gray body
being yellow and red on the dorsal, anal and tail fins. They have those
strangely shaped lower jaws which are extended into a beak-like affair
which became the main interest of the aquarists. Halfbeak swims almost
solely at the surface and always alert to the presence of its favorite
food, a mosquito larvae. Young Halfbeaks have no beak when born and are
less suitable to spend as much time at the surface like adults. Adult
males are lighter than females; they have a slightly notable anal fin.
Males fight each other by biting at each other's beaks. A gold kind has
been introduced, but its exact scientific identification is still in
question.
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