Tuesday, 4 September 2012

Live bearers- Beauty of aquarium

Live-bearing fish, often simply called live bearers, are fish that retain the eggs inside the body and give birth to live, free-swimming young.Species of interest to aquarists are almost always members of the family Poecilidae most commonly guppies, mollies, platies, swordtails, and limias. Live-bearing aquarium fish, often simply called livebearers, are fish that retain the eggs inside the body and give birth to live, free-swimming young. Because the newborn fish are large compared to the fry of oviparous fish, they are easier to feed than the fry of egg-laying species such as characins and cichlids. This makes them much easier to raise, and for this reason, aquarists often recommend them for beginners to fish breeding. In addition, being much larger makes them far less vulnerable to predation, and with sufficient cover, they can sometimes mature in a community tank.Most of the Poeciliidae are ovoviviparous, that is, while the eggs are retained inside the body of the female for protection, the eggs are essentially independent of the mother and she does not provide them with any nutrients. The benefit to an animal that reproduces by giving live birth instead of laying eggs is so obvious. Because the offspring is already well-developed and self-sufficient in ability to feed and move away from any danger or threats. The new generation's survival is somewhat less unsafe that it is for an egg or vulnerable larvae. Keeping the eggs in the female body until the young are well developed and able to swim directly after they are born reduces the number of eggs necessary to replace the parent generation. 

The guppy (Poecilia reticulata) is one of the most popular freshwater aquarium fish species in the world. It is a small member of the Poeciliidae family [females 4–6 centimetres (1.6–2.4 in) long, males 2.5–3.5 centimetres (1.0–1.4 in) long). Robert John Lechmere Guppy discovered this tiny fish in Trinidad in 1866, and the fish was named Girardinus guppii in his honour by Albert Günther later that year. However, the fish had previously been described in Germany. Although Girardinus guppii is now considered a junior synonym of Poecilia reticulata, the common name "guppy" still remains. Guppies are native to Antigua and Barbuda, Barbados, Brazil, Guyana, the Netherlands Antilles, Trinidad and Tobago, the U.S. Virgin Islands and Venezuela.

 Guppies are highly prolific livebearers. The gestation period of a guppy is 21–30 days, with an average of 28 days, varying according to water temperature. Males possess a modified tubular anal fin, the gonopodium, located directly behind the ventral fin, which is flexed forward and used as a delivery mechanism for one or more balls of spermatozoa. The male will approach a female and will flex his gonopodium forward before thrusting it into her and ejecting these balls. After the female guppy is inseminated, dark areas near the anus, known as the gravid spot, will enlarge and darken. Just before birth, the eyes of fry may be seen through the translucent skin in this area of the female's body. When birth occurs, individual offspring are dropped in sequence over the course of an hour or so.
Guppies prefer water temperatures of about 26 °C (79 °F) for reproduction. The female guppy has drops of between 2 and 50 fry at a time, typically ranging between 5 and 30. After giving birth, the female is ready for conception again within only a few hours. Guppies have the ability to store sperm up to a year, so the females can give birth many times without depending on the presence of a male. From the moment of birth, each fry is fully capable of swimming, eating, and avoiding danger. If not kept separate, the older, mature guppies will eat the fry, so the use of a breeder box, net breeder, or a separate 20–40 litres (4–9 imp gal; 5–11 US gal) tank is recommended. Live plants may be used as hiding places for the fry. Young fry take roughly three or four months to reach maturity. In the aquarium, they are usually fed finely ground flake foods, baby brine shrimp or, unless they are put in a separate tank, uneaten food from the adults. In addition, they nibble on algae.

Guppies have been selectively bred to produce a variety of colors and patterns. In the wild, male guppies are dull black or brown in colour, with some coloured spots, while females are fully dull grey. The wild guppies that showed the most colours in each generation were bred to produce the "fancy guppies" seen in pet stores and guppy shows today. The guppy has been successfully hybridised with various species of molly (Poecilia latipinna or velifera), e.g., male guppy and female molly. However, the hybrids are always males and appear to be infertile.[9] The guppy has also been hybridised with the Endler's livebearer (Poecilia wingei) to produce fertile offspring.

 It is essential for the serious aquarists to keep different varieties in separate tanks, since the majority colour varieties of the Swordtail, Guppy and the common Platy freely mate with other colours of their kind. Young Platies delivered by a female that has been in a community tank with color varieties other than her own will be accumulation of colours representing different feathers. None are expected to be especially attractive. The result of a haphazard breeding is, as it is with dogs, more likely to be unpredictable and unwanted than otherwise.

If you purchase breeding stock, fish should be selected from aquaria where only one variety of species desire is housed. Sexes should be separated as soon as possible. All baby livebearers look like females when born. Daily close inspection of each individual anal fin will soon reveal that in some fish it is beginning to thicken at its leading edge a fold backward. When these developing males are spotted they must be removed to continue their growth separate from the females. The development of gonopodium begins long before any other indications of the sex of male are in evidence, for example, colour in the guppy or the sword in the Swordtail. Once the fishes became adults, each must be carefully examined and those with the very best colour and desired markings must be selected as parents of the next generation. It is essential that selection must be thorough.


Wagtails: Yellow-gold with black fins or red with black fins.

Tuxedo: Gold or red backs with black sides and bottom. Belly is usually white.

Golden: Body pale yellow, some species with a black crescent on base of tail. Sometimes males have red patch below and extending into dorsal fin.

Reds: Two types. One blood-red, the other is brick-red. Males are totally darker.

Blue: Shiny, mirror-blue bodies, occasionally with some red in fins, black on base of tail.

Black-Blue: Black body with glitters of yellow or red. Shiny, not faded like Mollies.

Salt & Pepper or Spotted or Berlins: Red or yellow body covered with small black spots. Some species with black fins.
 Red-tailed: Males with more or less black dotting on gray-green background. Tail and dorsal glowed with red. Females are plain.

Yellow tailed: Same as above but with yellow instead of red.

Sunset: Like as mention above, color more yellow than gold. Scales may have pale black edges. Dorsal usually red.

Marigold: A rich golden-red in both sexes, with dorsal and tail reddish.

Nubain: Nearly all black. Some red or yellow part in front part of the body. Fins clear.

Hi-Fins: Available in various colors. Dorsal, especially of male, very big and long-rayed, carried like a flag.

Tuxedo-coloured: As usual Tuxedo Platy.

If you want to ensure a high survival rate for the Platy fry you should set up a separate fry raising aquarium. Some breeders chose to move the female Platy to the fry aquarium and let her give birth there. Others place a breeding net inside the large aquarium and put the female inside the net, where she and her offspring will be separated from the other fish. The female is not dangerous for her fry during the first 12 hours after the birth, since hormones will prevent her from feeling hungry. A Platy that is moved to a new aquarium or caught inside a net will always find the experience stressful. Stress can cause the female Platy to give birth prematurely, and you should therefore not move her until she looks like she is ready to burst. If you do not want her to experience stress, you can always let her give birth in the large aquarium without being netted. If you provide the fry with a lot of hiding places, they will try to stay away from hungry adults just like they would in the wild. Large gravel, large marbles and densely planted areas with bushy plants are good hiding places for fry. A lot of fry will probably be eaten, but at least a few fry from each batch will usually make it.

It is important to ensure that there are considerably more females than males in the colony; we would suggest a ratio 3-5 females to a male. This will ensure that the females will not get stressed by the male who will be constantly chasing them to spawn. The males are easily distinguished from the females. Swordtails have an elongated ray at the lower end of their caudal fin (sword); all male platies are smaller and less plump than the females and have a gonopodium at the ventral area. They use this to fertilise the females. Female platies can store unencapsulated sperm aggregates, called spermatozeugmata; these are used to fertilize eggs for a long time after spawning. As a result females are able to release up to six broods following a single mating.  Removing the males from the tank for a period of time is a strategy used by a number of hobbyists to ensure birth control.

Sword tail :

The male green swordtail grows to a maximum overall length of 14 cm (5.5 in) and the female to 16 cm (6.3 in). The name "swordtail" is derived from the elongated lower lobe of the male's caudal fin (tailfin). Sexual dimorphism is moderate, with the female being larger than the male, but lacking the "sword". The wild form is olive green in color, with a red or brown lateral stripe and speckles on the dorsal and, sometimes, caudal fins. The male's "sword" is yellow, edged in black below. Captive breeding has produced many color varieties, including black, red, and many patterns thereof, for the aquarium hobby. The Swordtail is perhaps the quintessential community aquarium fish. The time-tested popularity of the Swordtail can be attributed to its ease of care, peaceful temperament, and wonderfully diverse fin and color varieties. The most common Swordtail varieties include: Red Wag, Red Velvet, Marigold, Black Nubian, Pineapple, and Neon Swordtail. The male Swordtail is especially prized for its namesake feature, the showy extension on the lower part of its tail resembling a sword.The Swordtail requires an aquarium of at least 20 gallons that is well planted with plenty of room for swimming. Because of its peaceful nature, the Swordtail is well suited for the community aquarium. However, the male Swordtail can demonstrate territorial aggression towards other male Swordtails so care should be taken when housing more than one male. Also, the Swordtail is an accomplished jumper, so be sure to provide a secure cover for the aquarium. The Swordtail is a live-bearing fish related to freshwater aquarium favorites including guppies, mollies, and platys. As such, a female Swordtail can give birth to as many as 80 fry at one time. A spawning box is recommended, or if one is not available, provide dense floating cover to protect the Swordtail fry from potential predation by the adults. Unless it is your intention to breed Swordtails, the male Swordtail fry should be separated once the sex of the fry is determined. The Swordtail can begin breeding as young as three months of age and can quickly overpopulate an aquarium.

Types of Swordtail
  • Wag Swordtails - Available in red and gold varieties, these friendly fish have contrasting black fins which bring out their colours. They will only eat from the surface, so be sure to clean up the leftovers if you keep them on their own.
  • Black Swordtails - These handsome little fish will fit in well in almost any tank and are among the calmer varieties of swordtail to keep. Some strains have striking metallic blue spots.
  • Red Velvet Swordtails - A cross between green swordtails and red platies, these attractive fish have a rich velvety sheen. Males may sometimes be aggressive towards platy tankmates during courtship.
  • Painted Swordtails - With red, gold or green basic coloration, these fish feature curious black markings on the rear half of the body, as if they have been splashed with paint.
  • High-Fin Swordtails - With strikingly elongated dorsal, pectoral and anal fins as well as those impressive tails, these are among the most beautiful swordtails available. However, those long fins can sometimes get in the way during mating, making them difficult to breed.
  • Lyretails - These remarkable fish have one sword instead of two on their tails, sometimes almost half as long as their bodies. They are peaceful by nature and sometimes suffer from bullying by more aggressive fish.
Breeding Swordtails
Most swordtails are easy to breed, but it's quite a bit harder to preserve the offspring. Breeding swordtails requires careful attention. If you're to do it successfully you'll need to be able to drop all other commitments and be there when your fish gives birth.
Swordtails are livebearers who will breed quite happily within a community tank. When pregnant, the females start to swell up and develop a spot on the belly in a contrasting colour. It's difficult to know when they'll give birth as swordtail fry and quite often born prematurely - premature fry can still survive and grow, but are more likely to suffer defects. For this reason you may need to get to know an individual female in order to be properly prepared. Females who have been impregnated once will use stored sperm to produce more fry approximately once a month.
The easiest way to preserve the fry is to place the pregnant mother in a separate spawning tank with lots of weed or netting for the newly released fry to hide under. Be ready to remove the mother as soon as she's finished giving birth, or she will eat her own offspring.Swordfish are hardy and adaptable fish easy for beginners to keep, but with their bright colours and fascinating behaviours they also have lots to offer to the experienced aquarist.


 The natural lifespan of sailfin mollies is short, particularly in the case of the males, which may live less than a year after achieving sexual maturity. Depending upon environmental conditions, sailfin mollies may become reproductive in less than a year. Sailfin mollies are small fish. At one year of age, males typically range in size from 0.5-3 inch SL, while mature females are likely to be 0.5 - 2.5 inch SL. The size of adult males is directly correlated with population density. The greater the population, the smaller the average size of males. The maximum recorded size for this species is 150 mm TL. Fertilisation is internal, and is accomplished by means of highly modified fin elements within the anal fin of males that form a structure known as the gonopodium. Sailfin mollies produce broods of 10-140 live young, depending upon maturity and size, and females may store sperm long after the demise of their relatively short-lived mates. The gestation period for this species is about three to four weeks, depending upon temperature, and a single female may give birth on multiple occasions throughout the year. Although sex ratios of the broods are balanced, adult populations tend to be largely female, as males appear to suffer higher rates of mortality due to a greater susceptibility to predators and disease as a consequence of their brighter colours and a life devoted to frenzied breeding. There is no parental care exhibited by this species. A ratio of three females to one male is preferred, as with all live bearers, because the females are harassed by males to the point of exhaustion, and having more females gives the others a rest.


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