Swordtail: Species Profile

Category: Livebearer

Common Names: Swordtail

Scientific Name: Xiphophorus helleri

Family: Poeciliidae

Minimum Tank Size: 20 Gallons

Care Level: Easy

Temperament: Peaceful

Max Size: 4 Inches

Temperature: 72-82 F

pH: 7.0-8.0

Tank Level: All

Colors: Black, Orange, Yellow, White

Diet: Omnivore

Breeding: Extremely Easy

Red Wagtail Swordtail

Swordtail Fish Overview

Swordtail fish (Xiphophorus helleri) is a popular freshwater species for beginners and experts alike. They’re low-maintenance and colorful fish that are exciting to watch swimming around your tank. These hardy and peaceful fish make an excellent choice for beginners.

Distinguishing Features of the Swordtail Fish

Swordtail fish are a colorful species that come in various colors. As the name suggests, the male swordtail fish have a sword-like extension, called the caudal fin, that can be as long as its body.

Aside from the unique sword-like shape of their tale, they have common fish features. They resemble the Southern platy with their long body, pointy nose, and upturned mouth.

Whether male or female, these fish are widest near their midsection, though male fish have a slimmer body. Females will also have more of a rounded snout than their male counterparts.

Although they are vibrantly colored, their color fades when the fish are sick or stressed. When happy and healthy, there are plenty of colors to choose from.

The most common swordtail fish colors are orange, red, and black. There are various color morphs, including:

  • Neon Swordtail: The neon swordtail fish is irridescent but with a tinge of red, blue, and orange. They have bright neon stripes across their body.
  • Kohaku Swordtail: Kohaku swordtail fish has deep red eyes, a translucent body, and patches of white and orange.
  • Black Swordtail: Although it is black in color, its iridescent body can appear blue or green. Male fish will typically have a yellow tail extension.
  • Pineapple Swordtail: They have pale yellow bodies with orangish-red lines across them. They may be wholly yellow or have a patch of orange with fins matching their stripes.
  • Marigold Swordtail: Marigold swordtail fish have a similar color to a goldfish. They have a vibrant yellowish-orange body with intense orange fins and tails.
  • Red Wag Swordtail: Wag swordtail fish is one of the most popular varieties. They have a bright orange body and a dark tail.
  • Tuxedo Swordfish: As the name implies, the tuxedo swordtail fish has a black area with a tux-like appearance. There are various color combinations with this tuxedo look.
  • Twinbar Solar Flare Swordtail: The solar flare twin bar swordtail fish’s body has colors that fade from reddish-orange on the outside to pale yellow towards the center of its side.The top and bottom of the tail contain black stripes. The colors blend together, looking like a bright flash of light.
  • Hi Fin Swordtail: The hi fin swordtail fish has a similar elegance to that of betta. This variety has long, flowy fins and comes in various colors to choose from.
  • Lyretail Swordfish: The lyretail swordtail fish looks similar to the hi fin swordtail fish, though it has two of the sword-shaped protrusions on its tail.

Origin of the Swordtail Fish

The swordtail fish is native to parts of Mexico, Belize, Guatemala, Honduras, and other parts of North and Central America.

As part of the Poeciliidae family, they are relatives of the platy and guppy species. Like other members in this family, swordtail fish are livebearers, meaning they inseminate internally. Thus, this is one of the easiest species of fish to breed.

You can find these fish in varying bodies of water, from fast-flowing streams and rivers to quiet ponds or springs. These fish are olive green with red streaks along their sides in the wild.

Now, you can find swordtail fish in just about any pet shop that sells fish. They are famous for their unique appearance and easy-to-care-for nature, thus lots of people love to have them as pets.

Orange Swordtail

Average Swordtail Fish Sizes

When you purchase a swordtail fish in a pet shop or from a breeder, they will usually only be around three inches. Some people who are new to owning this species may be shocked when they reach half a foot in length.

Female swordtail fish can reach just over six inches, while males will grow up to five and a half inches in length. Males typically have more of a streamlined body, while females will have a slightly larger midsection.

Lifespan of the Swordtail Fish

On average, the swordtail fish will live three to five years. Although it’s impossible to predict how long you’ll have your pet, the better care they receive, the more likely they will live a long life.

Male vs Female Swordtail Fish

If you want to purchase a swordtail fish for its famous sword-like tail fin extension, then you will want to look at male fish; females do not have them.

In addition to having a long caudal fin, males will have slimmer bodies. Females will have a round tummy that will reach about half of an inch at maturity.

Keep in mind that females can easily reproduce as early as only three months old. If you do not want to breed your fish, keep the females and males separate.

If you’d like to breed your fish in the future, consider having a few females per male. Male swordtail fish will chase females in an attempt to mate. With too many males, the female fish will get a bit tired out from all the chasing.

Temperament of Swordtail Fish

One reason fish owners love the swordtail fish is because of its peaceful and social nature. They enjoy spending time with other fish, often forming loose groups.

These fish are active swimmers who will spend most of the day swimming in the middle or top of their tank. They need plenty of space to swim, explore, and engage with the other fish.

Males can become territorial and aggressive if too many other males are in the tank. As long as there are more females than males, your fish will be social and happy.

Swordtails are peaceful and social fish that enjoy the company of their own kind. These fish spend most of their time in the middle and upper parts of the tank and often form loose groups. They are active swimmers.

Red Swordtail Male

Swordtail Fish Tank Parameters

In the wild, swordtail fish live in various water conditions. However, this species does best in moderately hard water and plenty of vegetation.

Minimum Tank Size

A swordtail fish needs at least 15 gallons to thrive. They’re very active fish who need plenty of room to swim around and explore their enclosure.

Because these fish thrive in a community fish tank, you probably want more than one fish in the tank. If so, you’ll need more space for them all.

30-gallon aquariums are ideal for those who want a few different fish living together in the same space. You may also increase the tank size by 5 gallons per fish, starting from 15. So, for two fish, you would purchase a 20-gallon tank.

Swordtail fish are social and prefer to have other fish friends to engage with. Having two to three other fish is a great start, but you can add more so long as the tank is large enough.

Because they enjoy exploring, an elongated tape will suit them best. This allows your fish to journey back and forth to get their exercise actively.

Water Parameters

Swordtail fish like moderately hard water that is somewhere between 12 and 30 dGH. Since you’ll likely add a lot of plants for your fish, you’ll need to clean out their tank and change water from weekly to biweekly.

Regular water changes help prevent illness and stress for this species. Certain varieties, such as the Lyretail swordtails, are especially sensitive to unstable water.

To keep their water clean and stable, check the ammonia and nitrate levels daily to ensure everything looks good. You can purchase a test kit to better keep an eye on the pH of the water.


Swordtail fish can withstand temperatures between 64–82°F, though 75 to 79 degrees is ideal.


This species prefers slightly alkaline water with a pH level between 7.0 and 8.4.


As freshwater fish, there should be 0 ppt.

Tank Setup

The best way to keep your fish happy is to replicate their natural environment to the best of your abilities. Since they are used to dense vegetation, there should be plenty of plants for hiding and exploring.

On the other hand, these fish need plenty of space to swim around, so you want to ensure that there is enough room for them to swim freely.

Swordtail fish are expert jumpers and may attempt to leap out of the water. Investing in a tank with a secure lid will help keep them safely enclosed.


Swordtails don’t spend much time at the bottom of their aquarium, so you don’t have to worry too much about choosing a specific substrate.

You can pick a substrate that looks best for your tank and preferences without any fuss from your fish. A dark and sandy substrate will contrast beautifully with their bright bodies, so you may consider that option.

If you plan on owning bottom feeders, choose a substrate that they require.

Group of Swordtails on Gravel


Unlike substrate, decoration is going to be an important part of your tank. This active species enjoys having decor to swim around, explore, and hide behind.

Keep in mind that your swordtail fish will spend most of their time in the middle and upper areas of their tank. So, smaller pieces of decor are likely to go unnoticed by this type of fish.

Instead, choose more extensive caves or objects that they are more likely to come across. You don’t want too many items in their way, but they may enjoy having something near their chosen area.

You’re free to decorate the bottom of your tank with aesthetic preferences, just don’t expect them to spend much time around it.


Plants are especially important to swordtail fish since they’re plentiful in their native environment. Depending on your preference, you can choose live aquatic plants or use artificial plants.

We suggest choosing at least one or two live plants, but it isn’t a necessity. The most important thing is that your fish have plenty of vegetation (real or fake) to swim around.

Like with decor, you don’t need to crowd out your fish completely, and you shouldn’t. As you’re arranging your plants and decor, make sure is open space for them to swim.

Some popular underwater plants for swordtail fish include:

  • Java fern
  • Anubias
  • Dwarf hair grass
  • Scarlet temple


Like humans, swordtail fish are active during the day and then get rest at night. You don’t need to have lighting for your swordtail fish as long as they get other sources of light for at least 12 hours each day.

It can cause swordtail fish stress if they have any light during nighttime. So, if you do use tank lights, keep them off during the night so they can get sound sleep.

Keep in mind that swordtail fish don’t like harsh, direct lighting. If you do want a tank light, try to find something that isn’t too intense for them.


Filters are optional for a tank of swordtail fish. While some fish prefer filters to replicate their native environment better, swordtail fish are native to both still and fast-moving waters.

Like with lighting, if you do use a filter, keep it off at night. Sometimes the noise of the filter or the movement in the water can wake them up.


Swordtail fish prefer water environments that are on the warmer side. Consider investing in a heater that allows you to choose the correct temperature for them.

Although they can withstand more fluctuation than some other fish, it’s best to keep the water consistent as much as possible.

Red Swordtail Female


As omnivores, swordtail fish aren’t too picky when it comes to their food. In the wild, they feed on crustaceans, worms, and insects, along with plant matter and algae.

Even though they’ll eat just about anything you feed them, it’s best to give them a varied diet. Choose a variety of nutrient-rich foods, including pellets, flakes, vegetables, and live or frozen food.

For a plant-based treat, give them algae wafers every now and again. Algae and vegetables will help with their digestion, so make sure they don’t miss out on those.

To ensure they get enough protein in their diet, you can give them foods, including:

  • Brine shrimp
  • Daphnia
  • Bloodworms

Juvenile swordtails will need more protein than they do at maturity.

You’ll need to feed your swordtail fish 2-3 times each day. Only give them the amount of food they’re able to eat within a couple of minutes, and quickly remove any leftovers.

If any food floats to the bottom, they won’t eat it, and it can quickly dirty their tank.


Swordtails are one of the easiest fish to breed. As livebearers, the females are able to birth fry every 28 days.

Unlike many aquarium fish, swordtail fish will readily breed without any intervention. However, it’s best to have a separate breeding tank to have the best luck at breeding.

In your breeding tank, raise the temperature to 80 degrees. You’ll want to do so gradually to avoid shocking your fish.

Add lots of fine-leaf plants to the tank so that the young have areas to hide.

As you do with your regular tanks, make sure that the water conditions are clean. Add 2-3 female fish per male fish to this tan, so he has a few options.

When the male wants to breed, he’ll swim along with the chosen female and nip at her.

You’ll know your female is pregnant when her body swells, and she develops a visible black area near her anal fin. Usually, the pregnant swordtail fish will spend her time in one of the tank’s corners as she gets closer to giving birth.

Caring for Swordtail Fry

Females produce of 50-100 fry on average. Once she gives birth, move the female back to the original tank. This species will immediately attempt to eat their young if not removed.

Fry will need feedings three times per day. Their mouths will be too small for standard fish flakes or pellets, so give them powdered fish food or baby brine shrimp. After the fry are roughly 6 weeks old, they should be ready to live in the main tank.

As previously mentioned, make sure that the tank is large enough to house all of the new fish. Once in their new tank, they will be able to eat the same food as the other fish.

Common Diseases

Ich, fin rot, swim bladder disease, and cottonmouth is some of the diseases common to swordtails.

Signs of a healthy fish include:

  • Brightly colored
  • Actively swimming around their tank
  • Eating their regular portions of food
  • Have erect fins and tail
  • Have a plump abdomen

Ich, also referred to as white spot disease, is caused by protozoan parasites that affect freshwater fish.

You can easily spot a fish with Ich because it will have white spots on its body, fins, and gills. Fish with Ich will rub themselves against decoration in the tank and may lose their appetite or have reduced activity.

Luckily, Ich is a treatable condition. You’ll need to give your fish medication and raise the water temperature a few degrees until they’re better.


As livebearing fish, swordtails are susceptible to getting cottonmouth, also called cotton wool disease. It’s a highly contagious disease that will show up as white patches around their mouth, fins, or gills.

Fish with cottonmouth has ragged-looking fins, breathe more rapidly, and lose some of their colors.

Because an infected fish can easily give cottonmouth to other members of the tank, they’ll need to be quarantined until they’re better.

Treat the sick fish with antibiotics by adding some salt to their water. They don’t need a lot of salt, just one tablespoon for every five gallons. So, a 15-gallon tank would get three tablespoons of salt.

Fin Rot

As the name suggests, fin rot is a disease that will cause a fish’s fins to fray and eventually rot away if untreated.

Fish may get fin rot if their environment has poor water conditions or if they recently experienced a great deal of stress.

Varieties such as the hi fin or lyretail are more susceptible to this disease because of their long fins. In addition to tattered fins, fish with fin rot may experience inflammation and duller colors.

To treat fin rot, you’ll need to give infected fish antibiotics. You’ll also need to frequently change their water and continue to keep it as clean as possible.

Swim Bladder Disease

Swim bladder disease affects how a swordtail’s bladder functions. Fish get swim bladder disease from constipation, overfeeding, infection, or poor water quality.

FIsh with this ailment will exhibit unusual swimming behavior and may not be able to stay upright. Some fish will float to the top of their tank or sink to the bottom.

To treat fish with this disease, gradually raise the water temperature to 80 degrees and allow affected fish to fast for a few days.

Once they’re finished fasting, feed them a small pea to help with digestion. If there is an underlying cause, your swordtail may need further medical treatment.

Potential Tank Mates

Swordtail fish are social and peaceful fish that get along with many other species. To create a community tank, start with a few other swordtails.

You don’t have to limit yourself to a swordtail fish-only tank; there are plenty of options for potential tank mates. The best fish will be similarly sized and have a similar calm temperament.

Avoid adding any aggressive fish to a tank with swordtail fish as they cannot defend themselves. If a fish is more active than them, swordtails will become timid.

Here are some examples of potential tank mates:

  • Platy Fish
  • Mollies
  • Angelfish
  • Corydoras
  • Rosy Barbs
  • Guppies
  • Dwarf Gouramis
  • Neon Tetras
  • Celestial Pearl Danios
  • Kuhli Loaches
  • Otocinclus Catfish