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

Directory of Freshwater Fish

Livebearers

These popular fish are characterized by their breeding habits. The eggs are fertilized internally; in most species, sperm are transferred to the female via the male’s gonopodium—a tubelike projection of the anal fin—and the eggs subsequently develop in the relative safety of the female’s body. Some livebearers, including limias, have a restricted distribution in the wild and are not widely kept. Others, including guppies, platies, and swordtails, are popular worldwide. The ease with which they can be bred has led to the development of these fish into a host of exhibition varieties.

Four-Eyes (Anableps anableps)

• ORIGINS: Ranges from southern Mexico southward into northern parts of South America.
• SIZE: 10 1⁄2 in (27 cm).
• DIET: Live foods preferred.
• WATER: Temperature 72–86°F (22–30°C); hard (100–150 mg/l) and alkaline (pH 7.5).
• TEMPERAMENT: Alert by nature.

Although dullish brown in color, these livebearers are fascinating to keep, particularly because they breed so readily. Males are much smaller than females and rarely exceed 6 in (15 cm) in length. The female can produce a batch of 6–13 offspring, each measuring up to 11 ⁄2 in (4 cm) long, twice a year. An aquarium for Four-Eyes should not be filled to the top and must be covered to prevent them from leaping out. This species sometimes prefers brackish water.

Tropical Mosquitofish (Gambusia sexradiata)

• ORIGINS: Central America, occurring in parts of Mexico, northern Guatemala, and northern Belize.
• SIZE: 2 1⁄2 in (6.5 cm).
• DIET: Flake and small live foods.
• WATER: Temperature 61–77°F (16–25°C); hard (100–150 mg/l) and alkaline (pH 7.5).
• TEMPERAMENT: Social and nonaggressive.

Silver and blue feature strongly on the body of this fish, while the fins are marked with red and blue. Unlike other mosquitofish, this species does not tolerate brackish water. Include floating plants in its tank. Females are twice as large as males and have broader bodies. Some 10–35 young are born about a month after mating, and further broods follow at one-month intervals.

Mosquitofish (Gambusia affinis)

• ORIGINS: North America, occurring in the San Antonio River and the Rio Medina in Texas.
• SIZE: 2 1⁄2 in (6.5 cm).
• DIET: Prepared foods and small live foods.
• WATER: Temperature 61–77°F (16–25°C); hard (100–150 mg/l) and neutral (pH 7.0).
• TEMPERAMENT: Peaceful and social.

Both sexes are brownish with silvery underparts, but females are significantly larger than males. In the wild, these fish feed on mosquito larvae, and they have been widely introduced in tropical areas to control mosquito numbers. Up to 60 young are born after a gestation of 24 days. The tank should be well planted to provide hiding places for the fry, or they will be eaten. The fry will take small live foods and are best reared in their own tank.

Least Killifish (Heterandria formosa)

• ORIGINS: North America, where it is restricted to the state of South Carolina.
• SIZE: 1 3⁄4 in (4.5 cm).
• DIET: Prepared foods and small live foods.
• WATER: Temperature 61–77°F (16–25°C); hard (100–150 mg/l) and alkaline (pH 7.5).
• TEMPERAMENT: Social and nonaggressive.

A broad but uneven black stripe running down the sides of the body, and an obvious black blotch on the dorsal fin, help to identify this tiny fish. The males, which are just 3 ⁄4 in (2 cm) long, rank among the smallest of all vertebrates. Breeding is straightforward, but instead of giving birth to her brood of up to 20 fry all at once, the female produces offspring over an extended period of two weeks. A tank for Least Killifish needs to be densely planted.

Two-Spot Livebearer (Pseudoxiphophorus bimaculatus)

• ORIGINS: Central America, from Mexico southward to parts of Guatemala, Belize, and Honduras.
• SIZE: 6 in (15 cm).
• DIET: Prepared foods and small live foods.
• WATER: Temperature 72–77°F (22–25°C); hard (100–150 mg/l) and neutral (pH 7.0).
• TEMPERAMENT: Aggressive.

These fish are often brownish-yellow, and many of the scales have darker borders. A dark spot is evident on the caudal fin. The male is smaller and can be identified by his gonopodium. Females may produce more than 100 fry every two months. After giving birth, the females must be removed, or they will eat their offspring.

Blackbelly Limia (Poecilia melanogaster)

• ORIGINS: The Caribbean, where it is restricted to the island of Jamaica.
• SIZE: 2 1⁄2 in (6 cm).
• DIET: Prepared foods, plant matter, and small live foods.
• WATER: Temperature 72–82°F (22–28°C); hard (150–200 mg/l) and alkaline (pH 7.5).
• TEMPERAMENT: Males often harass partners.

Bluish body color is characteristic of these livebearers. They can be kept in groups, ideally containing more females than males (to prevent individual females from being chased constantly by would-be partners). Algal growth in the tank is beneficial because it supplements the diet. Blackbelly Limias are not prolific breeders; the females produce no more than 25 fry every six weeks or so after reaching maturity.

Black-Barred Limia (Poecilia nigrofasciata)

• ORIGINS: The Caribbean, where it is restricted to the Haitian part of Hispaniola.
• SIZE: 2 1⁄2 in (6 cm).
• DIET: Prepared foods, plant matter, and small live foods.
• WATER: Temperature 72–79°F (22–26°C); hard (100–150 mg/l) and alkaline (pH 7.1).
• TEMPERAMENT: Peaceful by nature.

The distinctive black barring on the body of this livebearer shows best under bright light. The body coloration itself is variable, although it tends to be yellowish, especially around the head. Mature males, which are slightly smaller than females, develop a hump on their heads as they grow older. They also have a narrow keel, which extends back on the underside of the body between the anal and caudal fins. Like related species, BlackBarred Limias will take a wide variety of foods and benefit from vegetable matter in their diet. Females have relatively large broods, producing as many as 50 fry at a time; broods are born every six weeks or so. The percentage of male offspring apparently increases when females are kept at higher temperatures.

ALL-SEEING EYES

The surface-dwelling Four-Eyes (see opposite) is so called because each pupil is divided into two parts. This adaptation enables the Four-Eyes to see simultaneously both above and below the waterline, alerting it to feeding opportunities and predators in either environment. The eyes are positioned high on the head, so the fish can lie in the water with the rest of its body submerged, rather like a crocodilian. In the wild it occasionally clambers out of the water to rest on rocks, and it should be given the opportunity to do this in the aquarium, too.

Girardinus (Girardinus metallicus)

• ORIGINS: The Caribbean, where it is widely distributed in Cuba, except in the extreme east.
• SIZE: 3 1⁄2 in (9 cm).
• DIET: Prepared foods, plant matter, and small live foods.
• WATER: Temperature 72–77°F (22–25°C); hard (100–150 mg/l) and alkaline (pH 7.1).
• TEMPERAMENT: Placid.

Both sexes have a metallic sheen, but the female (foreground of picture) is much larger than the male, which averages just 2 in (5 cm). A mature male can also be distinguished by his black gonopodium. Females can give birth every three weeks, with the average brood comprising around 50 fry. A densely planted tank will help to prevent the young from being cannibalized.

Malayan Halfbeak (Dermogenys pusilla)

• ORIGINS: Southeast Asia, ranging from Thailand and the Malay Peninsula down to parts of Indonesia.
• SIZE: 3 in (7.5 cm).
• DIET: Mainly small live foods.
• WATER: Temperature 77–86°F (25–30°C); hard (100–150 mg/l) and neutral (pH 7.0).
• TEMPERAMENT: Males are quarrelsome

Known as Halfbeaks because the upper jaw is much shorter than the lower, these livebearers often occur in brackish water. Insects, such as wingless fruit flies (Drosophila sp.) and mosquito larvae, can be bred as food for them. These fish can jump well, so cover their tank. Raising the water temperature encourages breeding, but stillbirths are not uncommon. The broods, consisting of about 30 young each, are produced at eight-week intervals.

Pike-Top Minnow (Belonesox belizanus)

• ORIGINS: Central America, ranging from southeastern Mexico down to Honduras.
• SIZE: 8 in (20 cm).
• DIET: Smaller live foods and fish.
• WATER: Temperature 79–90°F (26–32°C); hard (200–300 mg/l) and alkaline (pH 7.5).
• TEMPERAMENT: Aggressive.

This fish not only has a body shaped like a pike but also has similar predatory habits and hunts by ambushing its prey. Females are the larger sex and display yellowish or even orange coloration at the base of their anal fin. Pike-Top Minnows hide away in vegetation and may prefer brackish water. Their young are about 1 in (2.5 cm) long at birth and are rarely eaten by the female.

Merry Widow (Phallichthys amates)

• ORIGINS: Central America, found in Guatemala and from Honduras to Panama.
• SIZE: 2 in (5 cm).
• DIET: Prepared foods, plant matter, and small live foods.
• WATER: Temperature 72–82°F (22–28°C); hard (150–200 mg/l) and neutral (pH 7.0).
• TEMPERAMENT: Placid.

A black stripe through the eye, a black spot near the vent, and black edging on the dorsal fin typify this fish; males are significantly smaller in size. The Orange Dorsal Livebearer (P. a. pittieri) is a related but slightly larger form, with differentcolored edging on the dorsal fin. Females give birth every month, producing around 50 fry on each occasion—or sometimes as many as 150.

Spotted Skiffia (Skiffia multipunctata)

• ORIGINS: Central America, restricted to the Mexican states of Jalisco and Michoacán.
• SIZE: 2 1⁄2 in (6 cm).
• DIET: Prepared foods, plant matter, and small live foods.
• WATER: Temperature 68–77°F (20–25°C); hard (100–150 mg/l) and alkaline (pH 7.1).
• TEMPERAMENT: Placid.

A random pattern of black spots and blotches is evident on the body of the Spotted Skiffia. The difference in size between the sexes is much less apparent in this species than in some livebearers, but males can be distinguished easily by their notched anal fin and the yellow edging on the dorsal fin. This fin is also irregularly notched, which explains why these fish are also referred to as Sawfins. It is important not to allow the water in their aquarium to become too warm, because this may reduce the likelihood of successful breeding. The period between mating and birth can extend for up to 60 days, and there are often fewer than 20 fry in a brood. The young, which measure just under 1 ⁄2 in (about 1 cm) at birth, attain maturity at the age of about two months.

BEAK WRESTLING

Trials of strength are common between male Malayan Halfbeaks (see opposite). The fish lock their mouthparts together and remain in this position for 20 minutes or more, until the weaker individual releases his grip and backs off. This can cause injury to the beak, so it is not to be encouraged, and male Halfbeaks should generally be kept apart from one another. The protruding lower jaw can also be injured if these fish become alarmed and swim wildly at the sides of the tank. This is most likely to occur when they are first transferred to new surroundings.

Butterfly Splitfin (Ameca splendens)

• ORIGINS: Central America, in the Rio Ameca and the Rio Teuchitlán in Jalisco State, Mexico.
• SIZE: 4 1⁄2 in (12 cm).
• DIET: Prepared foods, plant matter, and small live foods.
• WATER: Temperature 68–84°F (20–29°C); hard (100–150 mg/l) and neutral (pH 7.0).
• TEMPERAMENT: Males are territorial and aggressive.

These livebearers can be sexed not only by their size but also by their coloration. The larger female has an irregular pattern of black spots over her body. In the more plainly colored male, shown below, the caudal fin is edged with black and then yellow, and the dorsal fin is more prominent. Females give birth to offspring that have an attachment resembling an umbilical cord; this disappears soon after birth. A typical brood consists of about 30 young, born about two months after mating. Young females giving birth for the first time have only a small number of offspring, which may vary noticeably in size. These goodeids require a well-lit tank with plenty of retreats, and they will browse readily on algae growing in their quarters.

Golden Bumblebee Goodeid (Allotoca dugesii)

• ORIGINS: Central America, occurring in the Mexican states of Jalisco, Guanajuato, and Michoacán.
• SIZE: 3 in (7.5 cm).
• DIET: Prepared foods, plant matter, and small live foods.
• WATER: Temperature 72–77°F (22–25°C); hard (100–150 mg/l) and alkaline (pH 7.1).
• TEMPERAMENT: Can be a fin-nipper.

The body of the male Golden Bumblebee is black and yellowish-gold; the larger female has bluish lower parts. House a male with two females, because he will bully a solitary female. The female gives birth to up to 70 fry every two months or so. Although goodeids are easy to keep, they are not as widely available as most other livebearers, such as the more colorful guppies and swordtails.

Rainbow Goodeid (Characodon lateralis)

• ORIGINS: Central America, found mainly in the upper Rio Mezquital in Durango State, Mexico.
• SIZE: 2 1⁄4 in (5.5 cm).
• DIET: Prepared foods, plant matter, and small live foods.
• WATER: Temperature 68–75°F (20–24°C); hard (100–150 mg/l) and alkaline (pH 7.1).
• TEMPERAMENT: Relatively shy

As the name suggests, this is a colorful goodeid; the adult male, shown below, displays areas of gold and red. The female Rainbow Goodeid produces fewer than 25 offspring per brood, with the brood interval being about eight weeks. Again, it is best to keep these goodeids in trios, but do not mix them with related species because of the risk of hybridization. Their aquarium should have plenty of vegetation.

Knife-Edge Livebearer (Alfaro cultratus)

• ORIGINS: Central America, found in parts of Nicaragua, Costa Rica, and western Panama.
• SIZE: 4 in (10 cm).
• DIET: Prepared foods, plant matter, and small live foods.
• WATER: Temperature 75–82°F (24–28°C); soft (50–100 mg/l) and neutral (pH 7.0).
• TEMPERAMENT: Shy, but may be aggressive.

A row of scales projecting beyond the lower edge of the body gives these fish their distinctive knifelike appearance. Both sexes are pale yellowishbrown in color. Clear, clean water is very important for the well-being of Knife-Edge Livebearers; regular partial water changes are essential, since the fry in particular are prone to bacterial ailments. These fish can sometimes be kept in slightly brackish surroundings. Provide the fry with brine shrimp as a rearing food.