Freshwater Fish

Swordtail Fish – Xiphophorus helleri: Care Guide

Swordtails are a delightful and popular freshwater species in the aquarium community. Due to their beauty and low-maintenance nature, these fish are great choices for beginners (or experts who don’t want any trouble).

This guide will teach you the basics of swordfish care. You’ll learn about their diet, lifespan, size, tank mates, habitat setup, and more!

Species Summary

The swordtail fish (Xiphophorus helleri) is an ever-popular freshwater species that hails from North and Central America. They belong to the Poeciliidae family and are closely related to other common fish such as the platy and guppy. Like others in the family Poeciliidae, these fish are prolific carriers of life that are more than willing to spawn in captivity (more on that later).

In the aquarium trade, swordtails are some of the best sellers. They are available at most pet stores and are a favorite among breeders.

Thanks to their penchant for crossbreeding and ease of care, there are many different colors and variations. Combine that with its already iconic look, and you have a display-ready species!


The most defining characteristic of the swordfish is the caudal fin of the male. The lower lobe elongates, creating a sword-shaped bulge that can be as long as the rest of the body.

Author’s note: Females do not have the longest lobe, so it is easy to differentiate the sexes for reproduction.

Beyond that characteristic trait, swordtails have a very «standard» body type. They look strikingly similar to the southern platy. Swordtails sport the same streamlined body, wide tail fin, pointed snout, and upturned mouth. The fish are widest where the dorsal and pelvic fins appear in the midsection.

When it comes to color, there is a lot of variety! Wild specimens usually have an olive green base and a brown lateral stripe across the sword. However, crossbreeding has provided aquarists with all sorts of unique aesthetic options.

Some of the most widespread morphs are red, orange and black. However, there are also multicolored swordtails and exotic varieties with different patterns.

Life expectancy

The average life expectancy of swordtail fish is around three to five years. Fish that are kept in the best and most stable living conditions tend to live the longest.

There is no way to predict this with any certainty, as luck and genetic predispositions can affect a swordfish’s lifespan. That said, the level of care you provide will have a huge impact on this.

Average size

These are medium-sized freshwater fish. The average size of a swordtail fish is around 5.5 inches long when fully grown.

Author’s note: Males are the smallest of the group despite the elongated tail. They rarely exceed the length indicated above. On the other hand, females often grow about an inch longer.

Swordtail Fish Care

Swordtail fish care is quite simple as these fish are adaptable and not very demanding. In other words, they are easy to keep healthy! They thrive in a wide range of environments and are very forgiving of common beginner mistakes.

Of course, these fish still have their preferences. For best results, follow the care guidelines set forth below.

tank size

The first thing to consider is the size of the aquarium. Some aquarists have had success keeping swordtails in freshwater tanks that hold as little as 10 gallons.

However, most recommend starting with a minimum of 15 gallons. These fish are quite active and the extra space will do them good.

Now keep in mind that a 15 gallon tank is best for a single Swordtail. You will most likely keep a small group! Larger groups are better for their social development (more on this later).

If that’s the case, aim for a 30 gallon or larger aquarium. Larger tanks are always better for groups or if you plan to keep a group of community fish together.

water parameters

The natural distribution of the swordtail in the wild is surprisingly wide. Generally, these freshwater fish live in warm streams and rivers with tons of vegetation. While they come from many places in North and Central America, they are most prevalent in Belize, Guatemala, and Mexico.

Interestingly, swordtail fish can live in virtually any freshwater environment. Whether it’s a shallow mountain stream or a deep river, they will adapt. Swordtails can even thrive in brackish estuaries near the coast!

This adaptive lifestyle is part of the reason swordfish care is such an easy task. It has a wide range of conditions with plenty of wiggle room to get things right!

  • Water temperature: 65°F to 82°F (75 to 79 degrees seems to be the sweet spot)
  • pH levels: 7.0 to 8.4 (slightly alkaline)
  • Water hardness: 12 to 35 dGH (very hard)

how to decorate your tank

The best course of action for any fish is to provide a natural biotope setting that mimics its natural environment. Again, the versatility of the sword tail makes this a pretty easy job.

The most important thing swordfish need is space and some plants to hide in.

This species is active and likes to swim across the tank for exercise and play. They tend to stick to the middle and upper parts of the water column. As a result, being picky about the substrate material is not something you need to think about when it comes to your swordfish. Instead, choose one that is suitable for any bottom feeders you may have in the community.

You can use larger rock caves or driftwood to create some additional forms of shelter. However, there is no guarantee that your swordtail fish will use it. This is especially true if the decoration is near the bottom of the tank.

It is better to concentrate on the plants. You can use live or artificial silk plants. Live plants will do more to enhance the underwater environment.

You can use any plant that is safe and provides adequate cover. Some of the more popular cultivars are java fern, Anubias, and dwarf grass. Just make sure you leave an open space for swimming.

Author’s Note: Other than a few plants and hiding places, the only other crucial accessory is a sturdy tank top. Swordtails are powerful jumpers, so it is not uncommon to see these fish leap out of the water to their death below. A secure lid will prevent those mishaps!

Possible common diseases

Like other life-bearing species, swordfish are very hardy. They tend to have an easier time staying healthy than other fish that lay eggs.

But of course, no fish is immune to disease! Swordtail fish can suffer from all the common ailments.

Ich is one of the most widespread health problems in the fishing world. It is an ectoparasite that wreaks havoc on the immune system of fish. It usually manifests as whiteheads all over the body, so it’s important to address it as soon as possible.

This disease is highly contagious and can quickly wipe out an entire community. Fortunately, it is relatively easy to treat with over-the-counter medications and quarantine.

The same goes for another common health problem, fungus. Swordtails can suffer from a fungal infection that many refer to as cottonmouth. It causes fluffy growth around the fins and mouth. In most cases, antibiotics will take care of the fungus.

The best way to avoid disease is to be aware of tank conditions. Monitor parameters closely (invest in an aquarium test kit) and do water changes about every two weeks.

Author’s Note: Swordtail fish seem to fall prey to disease after large fluctuations in temperature. High levels of ammonia and nitrates can cause undue stress, which also increases your risks. Keeping the environment in optimal conditions will prevent outbreaks.

Food and Diet

Swordtail fish are natural omnivores that will eat almost anything in the wild. Insect larvae, plant detritus, and tiny microorganisms are often the name of the game.

Swordtails do best on a varied diet of commercial foods and occasional high-protein snacks in an aquarium. Stick to nutrient-rich flakes or granules. To offer some plant-based cooking, offer seaweed wafers from time to time.

These fish also appreciate live, frozen and freeze-dried foods. Brine shrimp, daphnia, bloodworms, and all the usual high-protein snacks work.

The juveniles should have a little more protein than usual. They require a lot of protein-based foods to grow.

For both adults and young people, the ideal is two or three small meals a day. Provide enough food for the fish to eat within two minutes during each feeding. If there are any leftovers, sieve them to avoid ruining the water conditions.

behavior and temperament

This species is fantastic for communities. One of the reasons swordtail care is so manageable is that they are naturally peaceful and quite friendly. During the day, they will interact with other fish as they explore the upper parts of the water column.

While not a schooling species, swordfish prefer to stay in the company of others. These fish like to form groups periodically before going off and doing their thing.

That said, there is the possibility of some aggression. The only time swordtails seem to display aggressive behavior is when there are multiple males in the same tank. Males can be territorial, so keeping a higher proportion of females is important to keep the peace.

tank mates

Swordtails get along with most like-minded species. They are peaceful and passive.

When planning a community tank, start by adding other swordtails. You should never leave these fish alone. A small group socialization can do a lot of good!

As mentioned above, you must have more women than men. The recommended ratio is four females to one male.

Beyond other swordtail fish, you have many options when it comes to tank mates. Stick to fish of a similar size with the same calm temperament.

Avoid aggressive or boisterous fish. Swordtail fish cannot defend themselves against attackers. In the presence of more active fish, they also become timid and timid.

The best course of action is to house them with common social fish. Here are some excellent species worth considering for swordtail tank mates:

  • Platy Fish
  • molly fish
  • Angelfish
  • cory catfish
  • pink quills
  • dwarf gouramis
  • neon tetras
  • Celestial Pearl Danios
  • kuhli loaches
  • otocinclus


Swordtail breeding is a simple process. Like other life carriers, they reproduce rapidly in captivity. Under the right conditions, females can give birth once every 28 days!

While they will easily breed in your main tank without any intervention, it is best to provide a separate breeding environment. A rearing tank increases the chances of survival of the fry.

Raise the temperature of the breeding tank gradually to about 80 degrees. Place several fine-leaved plants throughout the tank to give the fry some places to hide.

Keep tank conditions in good condition and condition your breeding pair with high-protein foods. When they are ready, the fish will spawn. The females will begin to fill with eggs as a visible spot of gestation develops.

Usually pregnant females go to one corner of the tank and stay there as the time to give birth approaches. Eventually, fully formed swordtail fry will emerge!

Author’s Note: Be sure to remove adults after the female gives birth. These fish do not exhibit parental instincts and will immediately attempt to eat their young.

Fish fingerlings are too small to eat standard flakes or pellets. Therefore, you should provide powdered fish feed, infusoria, or newborn brine shrimp. Continue feeding the fish until they are big enough to eat traditional foods.


As you can probably see, swordtail care is nothing to be afraid of. These freshwater fish are a joy to keep and should not cause any problems.

As long as you are familiar with their basic care requirements and give them the attention they deserve, your swordtails will thrive.

We hope you found this guide helpful and encouraged you to give this amazing species a try!

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