Green Swordtail fish (Xiphophorus Hellerii) are often recommended to new aquarists because they are considered hardy fish that can survive well even in less than optimum conditions. They are easy to feed and handle, and therefore easier to breed as well. They give birth to live fry, the baby Swordtails are robust at birth and very easy to raise unless they are eaten by larger fish.

General information of Swordtail fish

  • Swordtail-fish
  • Male Swordtail. Image from Wikipedia.org.
  • Scientific name: Xiphophorus Hellerii
  • Family: Poeciliidae
  • Common name: Green Swordtail, Swordtail fish
  • Length: 5.5-6.3 in (14.0 – 16.0 cm)
  • Activity: top level of the aquarium
  • Care level: very easy
  • Lifespan: 3-5 years, live longer when kept in good environment.

Swordtail fish originally came from Central America. Wild Swordtail fish is actually olive green in color with red or brown lateral stripes along its dorsal. However, the Swordtail fish has been widely bred for its unique tail and this has produced many color varieties, such as black, red, or sliver. The color variations and patterns are especially pronounced on its tail.

Since only the male Swordtail fish bears a significant tail, most of the colorful species you see in aquariums are male. However, the Swordtail fish is also well-known for another aspect among aquarists – they are live bearers! Swordtail fish gives birth to live fish fry instead of laying eggs. This is act of giving birth to live fry is a wonder to watch and amazes both aquarists and the layman observer alike. Besides their sword-like tail, Swordtail fish are also popular aquarium fish for this reason.


Female Swordtail

Because Swordtail fish are hardy, they become a nuisance species in many of its non-native countries. Their populations have been established in regions of South Africa as well as along the east coast of Australia. It is not known where these feral populations came from, but they are likely to have been a result of aquarium Swordtails being released into the wild after their owners have gotten tired of keeping fish.

For better or worse, the Swordtail fish remains as one of the most popular tropical aquarium fish. Numerous inbreeding for color perfection have reduced the vigor of Swordtail fish, but more recently, the wild type Swordtail has seen a resurgence in aquarium tanks for their ability to survive well in community tanks.

How to keep Swordtail fish?

Aquarium conditions:

  • Tank size: at least a 30 gallon tank
  • Stocking ratio: 1 male x 3 females
  • Temperature: 70 -78 °F (21.1-25.6 °C)
  • Optimal pH: light alkaline (pH 7.0-8.3)
  • Water hardness: (dH) 10-15
  • Lighting: Medium
  • Filtration: Medium
  • Aeration: Medium.

Fish tank setup and stocking

Being strong swimmers, Swordtails need a fairly large aquarium tank relative to their size (5-6 in length when maturing). On the average, it is recommended that you have approximately 10 gallons of tank capacity for every Swordtail.

There is no limit on how many Swordtail fish you can keep in the same tank as long as you can afford a large enough tank size to house all your Swordtail fish comfortably. But male Swordtail fish can be territorial and will fight other males in the tank. Therefore you shouldn’t keep a tank full of male Swordtail fish, no matter how beautiful they might look.

Swordtails in community tank

In fact, you should keep males to female Swordtail fish in a ratio of 1 is to 3. Males are known to harass the female fish, so you should have more females than males to keep them from being stressed out. You should set up your aquarium with plants and other covers available for females to hide from males and also for males to hide from each other. But be careful not to use too many drift wood in your tank as they can cause your water to turn acidic. Swordtail fish prefer brackish water conditions at between pH 7 to 8. The tank should acquire a hood to prevent the fish from jumping out and death.

Feeding and fish foods for Swordtail

Like most small tropical freshwater fish, Swordtail fish will take well to a diet solely consisting of tropical flakes or pellets, and unfortunately, that is what most Swordtail fish are fed in homes. Simple logic will suggest to you that a varied diet will do wonders for your Swordtail fish development.

TetraMin Tropical FlakesTetraMin Tropical Flakes TetraColor Tropical GranulesTetraColor Tropical Granules Tetra blood worms freeze dried treatTetra blood worms freeze dried treat

A favorite supplement for Swordtails is blood worms, they are very rich in protein and contain healthy fatty acids like omega 6. But most importantly, blood worms can enhance the color of fish with their pigments and are a staple of any tropical fish diet, including Swordtail fish. There is another fish food known as freeze dried blood worms which are also commonly used as a form of inexpensive substitute to blood worms.

A little vegetarian diet is also a good idea for your Swordtail fish. You can feed it frozen spinach, zucchini or even bananas. Brine shrimp is another good supplement that you should consider adding to the diet of your Swordtail fish.

In general, you should feed your Swordtail fish twice a day with small pinches of food that sink slowly. Continue to feed your fish in small pinches until they start to feed slowly.

See more about fish foods and feeding: https://lovefishtank.com/best-freshwater-fish-food/

How to breed Swordtail fish?

Like most other fish, the Swordtail fish breed only under the right water conditions. No fish will risk wasting precious resources by having young in suboptimal conditions for the fry to survive. Suitable aquarium breeding conditions is when the environment is best suited for your Swordtail fish to live in.


Female Swordtail

Typically, swordtail fish survive well in brackish water with pH ranging from 6.8 to 7.8. While the adults can survive in a range of pH, fish fry are much more vulnerable and survive in more stringent conditions. That is why swordtail fish must be provided with the best possible environment before they will start to breed.

Breeding can be encouraged by raising water temperature up by one or two degree to between 25 and 27 degree Celsius. Warmer water suggests a more plentiful environment therefore making it the right opportunity to breed.

Male swordtail fish are of course, required to mate with female swordtail fish for breeding. Male swordtail fish are known to pester females even when they are pregnant, this can cause stress for the pregnant. It is important to set up your aquarium with lots of cover and hiding places using plants. This allows the females to hide away from the males and also provides hiding places for the new born fry when the female swordtail fish gives birth.

Marina Hang-On Breeding BoxMarina Hang-On Breeding Box

When a female swordtail fish becomes pregnant, dark spots will begin to appear around her anus region. These spots are actually the eyes of fish fry showing through her scales. Her belly will start to bloat and eventually when it appears as if her belly will explode; it means she is ready to give birth anytime.

You can either choose to isolate her into a nursing tank for her to give birth, or you can let her give birth in the common tank with other swordtail fish or even other species of fish around.

If you do put her in a nursing tank, make sure that the water in the nursing is well cycled and does not contain high levels of ammonia content. Swordtail fish fry are very vulnerable at birth and can quickly die from poor water conditions.

Some owners prefer to let the fish fry try and survive on their own in the larger tank. In a sense, this is a selection process where only the fittest swordtail fish fry will survive. But of course, you must also provide adequate cover and protection in the tank for the fish fry to stand a chance. If your fish tank is open and without any cover, no fish fry will survive no matter how fit they are.

A problem with not placing swordtail fish fry into a nursing tank is feeding them. They need to be fed and they will have to contend with other adult fish for any food that you are placing into the tank. Swordtail fish fry thrive on spirulina algae and newly hatched brine shrimp. The spirulina is very nutritious and will make the fry grow quickly while brine shrimp will help the near transparent fish fry gain their colors sooner.

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