Swordtail Fish

Swordtail Fish

Wild Swordtails are found from southern Mexico and down to Guatemala in Central America. The name Swordtail is derived from the body of the male Swordtail. The bottom ray of his caudal fin is extended, and points out from the body like a sword. The female Swordtail is without sword, and she can also be distinguished from the male by her more rounded body shape. Today you choose between red, black, green, albino and even neon coloured Swordtails since Swordtails have been extensively bred in captivity during many years. You can also choose between a lot of different Swordtail types, such as the Red Simpson, the Spotted Swordtail, the Gold tux Swordtail and the fanciful Lyretail.

You can keep one Swordtail in a 10 gallon aquarium or larger. Since the Swordtail is an active swimmer it will do best in an aquarium larger than 10 gallons, since this will give the Swordtail room to swim around a lot more. Swordtails are quite tolerant when it comes to water temperatures, and can live in temperatures from 18 to 27 degrees C. In the wild, the Swordtail live in brackish waters and your Swordtail will therefore appreciate a brackish aquarium. Swordtails are often kept in freshwater community aquariums, but brackish water is always better. Keep the pH in the 6.8-7.8 range.

The Swordtail fish is a livebearer, so unlike many other fish species a female Swordtail will give birth to fry instead of depositing eggs. The male Swordtail fertilizes the eggs inside the female, and the eggs develop into fry inside her belly. Just like with many other Livebearers, it is easy to get Swordtails into spawning condition. It is even possible for a female Swordtail reproduce in an aquarium without any male Swordtail present, since she can store enough sperm to fertilize six batches inside her body. If your female Swordtail unexpectedly gives birth without a partner, she has been kept with male Swordtails earlier and saved sperm since then.

swordtail fish
Male swordtail. Copyright www.jjphoto.dk

A common way of making the Swordtails breed in aquariums is to turn the water temperature up and keep it between 25 and 27 degrees C. The levels of solvable waste should be as low as possible, and you should also monitor the pH and make sure it stays in the ideal 6.8-7.8 range. When dark spots show around the anus of the female Swordtail and she looks as if her belly will explode any minute, you know that she will soon give birth. The dark spots that you can se around her anus are the dark eyes of the fry showing through her scales. You can let her give birth in the large aquarium, or set up a special fry aquarium to ensure a higher survival rate. Regardless of what you choose, the aquarium where she gives birth should be decorated with bushy plants. Swordtails want to give birth in a place where there is a lot of hiding places for the fry. This is a fine habit, since most adult fish, as well as other aquatic residents, like to eat fry. It is common for female Swordtails to give birth sitting at the bottom of the aquarium. If you decide to let the female Swordtail give birth in the large aquarium, densely planted areas with bushy species are absolutely imperative if you want any fry to survive.

When the fry is born they will happily eat liquid fry food, newly hatched brine shrimp or flake food that you have crushed into a fine powder. Their diet should also ideally include Spirulina algae. The combination of Spirulina and Brine shrimp is known to make the fry grow very rapidly, and this diet will usually make them show their true colours earlier.

Picture of female swordtail fish
Female swordtail. Copyright www.jjphoto.dk

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