Next to the guppy, the most popular aquarium fish for breeders and hobbyists is the swordtail (Xiphophorus helleri). Baby swordtails, known as fry, aren't hatched from eggs, but are born alive and already swimming. These freshwater fish, which are part of the group of livebearers, resemble platties and guppies, which also give birth to live babies. Other livebearing fish include mollies and four-eyed fish. Although they're easy to breed and maintain, new breeders and hobbyists should learn some basic tips about their care.
The male swordtail has a "sword" extending from the bottom of its tail, giving the fish its name. Colors aren't linked with gender, so you can't distinguish male from female babies. A few color variations include black swordtail, gold tuxedo, black velvet and red velvet. Their colors may range from orange, red, green and yellow to black (which is generally a mixture from another color). Sometimes, the fry will have a slight change in color as they mature. The fry's base color can usually give hints of its adult coloring, suggesting whether their baby colors will turn into grayish or reddish shades.
Although swordfish make good community fish, they can also show different behavioral patterns and temperaments. Personalities may range from peaceful and harmonious to bullish, but baby swordfish are mostly easy-going. It's the older males that are particularly more aggressive with one another.
As with any livebearing fish, it takes a male and female to produce babies. However, it's best to have at least two to three females per male. Because male livebearers are known to pester females, include plants in your aquarium to provide hiding spaces. A pregnant female is distinguishable by a baby bump that appears about a week or two following mating. The female will generally give birth to the fry around 30 days after mating. It's wise to separate your pregnant female by placing some live plants in the aquarium.
Typically peaceful fish, baby swordtails can easily live in a community tank or aquarium. Unfortunately, parents often eat their young, so the newborns need to be protected from adults until they grow larger. Provide many floating plants, as sometimes plants can camouflage fry. However, it's still safer to keep fry in separate tanks. These fish thrive in a tank with plenty of room for swimming. As with any livebearing fish, swordtails enjoy a pinch of salt in their water, but it isn't essential. Baby swordtails prefer water that's neutral to slightly alkaline, with a pH of around 7.0 to 7.3. The water needs to be about 72 to 79 degrees F (22 to 26 degrees C).
Feeding Baby Swordtails
Hatched baby brine shrimp or newly hatched daphnia are excellent foods for baby swordtails. They can also can be fed with either dried or liquid fry foods made for livebearers. These foods can be found at pet stores or through websites. Although baby swordtails can live on dried fry food, they do better if you include live food in their diet. Feed babies about three times daily.
In addition to separating babies from adults, do not feed large fish food flakes to baby swordtails. However, you can feed them ground up flake food. Because the flakes are sometimes large, fry aren't able to fit a whole piece into their small mouths.