[Ebook] Encyclopedia of Aquarium & Pond Fish – Directory of Freshwater Fish – Livebearers – Guppies

Directory of Freshwater Fish

Livebearers

Guppies

Guppy (Poecilia reticulata)

• ORIGINS: South America, occurring in the Caribbean and in South America north of the Amazon.
• SIZE: 2 in (5 cm).
• DIET: Prepared foods and small live foods.
• WATER: Temperature 70–77°F (21–25°C); hard (100–150 mg/l) and alkaline (pH 7.5).
• TEMPERAMENT: Placid and social.

One of the best known of all tropical fish, the Guppy is named after Rev. Thomas Guppy, who identified it on the Caribbean island of Trinidad. The several thousand varieties available to aquarists today are far removed from their wild ancestors and can be found in a wide range of colors and with many different body patterns and fin types. The different color variations are displayed most impressively in male fish, which are naturally more colorful as well as smaller than females. (All the fish illustrated here are male.) Guppies show well as a group in a single-species tank, but they can also be kept with other nonaggressive fish as part of a community aquarium. The female Guppy gives birth to live offspring, but unfortunately these are likely to be cannibalized soon after birth, even in a breeding tank setup, unless the young can escape out of reach. Various breeding traps are available for this purpose (see p.66). When buying these fish, it is worth remembering that the largest females give birth to correspondingly bigger broods.

One of the most significant factors to consider when breeding guppies is that a female needs to mate only once in order to continue producing young throughout her life—potentially giving birth to seven or more broods using sperm stored in her body. This is why even if you choose a well-marked male and female from the same tank in a pet store, the likelihood will be that at least some of the young will not be the offspring of that particular male (although the majority of offspring are likely to be the result of the most recent mating). This also explains how females kept on their own can give birth to young.

The only way to be sure of the parentage of guppies is to separate the sexes as early as possible. As soon as the young males can be recognized by their gonopodium—usually when they are about three weeks old—they should be transferred to a separate tank. The females will be noticeably larger than the males from three months onward, by which time some of the males will already be sexually mature. A female guppy will have her first brood approximately a month after mating. The number of offspring produced is likely to be small at first, sometimes no more than 10, but it increases to between 50 and 100 per brood as the female grows bigger. Some strains are more prolific breeders than others.

Selective breeding of guppies began during the 1950s, but unfortunately, a number of strains—even some that are carefully maintained—are not stable. This means that many of the resulting offspring may not display the most desirable characteristics of their parents. Cobra patterning is one of the most stable characteristics in terms of markings. This is a dominant genetic characteristic, so well-marked individuals are always likely to pass their cobra patterning on to the next generation. However, recessive characteristics, such as tuxedo patterning, may disappear for several generations of a particular bloodline and then reemerge unexpectedly at a later stage.

• Wild Guppy These fish may be found in brackish water, and the addition of salt to their aquarium is recommended. Wild Guppies are not readily available today, and domestic strains will prove far more adaptable.
• German Yellow Guppy Named after its country of origin, this is a particularly striking variety in which the enlarged caudal fin and the dorsal fin are both yellow. Fin shape, as well as color, is important in fancy guppies.
• Blonde Guppy The red caudal fin and rear part of the body contrast with the lighter blonde coloration seen on the underparts near the head. The use of color food is often recommended for red strains of guppies.
• Red Tail Half-Black Guppy As with other strains created by selective breeding, fertility may be impaired if these fish are heavily inbred. Not all such strains are commercial products; some are bred by enthusiasts only.
• Silver-Backed Tuxedo Guppy The distinctive black area on the flank varies in size and density between individuals.
• Rainbow Cobweb Delta Guppy This is another “composite variety,” so called because of its varied coloration, cobweblike pattern, and the delta shape of its caudal fin.
• Golden Snakeskin Delta Guppy This is one of a number of guppy varieties that have become very popular in Russia. It is thought that the famous Moscow Blue strain may have evolved from the Snakeskin line.
• Cornflower Blue Delta Guppy (below) The exact patterning on the broad tail varies between individuals, allowing them to be distinguished quite easily, but the body coloration should be a consistent feature.
• Red Varitail Guppy (above) Broad-tailed guppies like the Red Varitail tend to be more popular than those with narrow tails, because the wide caudal fin allows for some striking tail patterns to be developed.
• Gold Cobra Delta Guppy Of American origin, Cobra Guppies are now popular internationally. The male (seen above) is always more colorful than the female, although she may display a patterned caudal fin in some strains.
• Golden Lyretail Guppy The upper and lower rays of this guppy’s caudal fin are greatly extended, creating a sleek appearance. It is important in the lyre-tailed forms that these two areas are symmetrical and even in size.
• Tuxedo Rainbow Delta Guppy When selecting these and other delta-tailed guppies, be sure to check that there is no significant damage to the broad caudal fin, which could lead to a life-threatening infection.
• Tuxedo Multicolored Delta Guppy The tuxedo characteristic (the black area toward the rear of the body) can be combined with different colors to striking effect. This variety also has the broad delta-tail.
• Flamingo Guppy The breeding trend with this strain has been to improve the depth of the red coloration. Early examples were considerably paler than those being bred today. Flamingo Guppies are also called Golden Redtails.
• Blue Tuxedo Guppy This particular variety is also described as the Blue Delta-Tail Half Black, based on its body coloration. The broad caudal fin is predominantly blue, with variable black markings.
• Green Variegated Delta Guppy Like other guppies with a delta-shaped caudal fin, the Green Variegated Delta Guppy is a slower swimmer than sleeker-tailed forms. This variety should be housed in a single-species tank.

Endler’s Livebearer (Poecilia reticulata)

• ORIGINS: South America, where this attractive wild form of the Guppy is found in parts of Venezuela.
• SIZE: 2 in (5 cm).
• DIET: Prepared foods and small live foods.
• WATER: Temperature 70–77°F (21–25°C); hard (100–150 mg/l) and alkaline (pH 7.5).
• TEMPERAMENT: Peaceful and social.

These spectacularly colored fish are a wild form of the guppy. Despite this, Endler’s Livebearers must not be housed with guppies, because they hybridize readily with them and soon lose their distinctive characteristics. The body colors of Endler’s Livebearers range from blues and greens through to oranges and reds. These fish are prolific breeders, but they have a relatively short life span of no more than a year.

THE GRAVID SPOT

Breeders of popular livebearers have relied on the appearance of the dark gravid spot to indicate that a female is about to give birth. This spot is formed by the dark lining of the abdomen, known as the peritoneum, which bulges against the sides of the female’s body just before she gives birth, pushed out by the increasing size of her brood. The gravid spot is less apparent in swordtails, simply because the female’s abdominal wall is more muscular. Once the gravid spot has appeared, the female should not be moved; otherwise, she is likely to abort her brood.