How to Care for a Swordtail Fish Complete Care Guide: Size, Food, Tank Setup & More!

If you are looking for a fun, but low-maintenance fish, then the swordtail fish is a fantastic option.

These fish are well-known as great options for beginner fish keepers, and they can be kept alongside quite a few other fish species quite happily.

The swordtail fish is a popular freshwater tank fish that takes its name from the sword-like fin the male fish display. Swordtails are hardy and quite adaptable, making them easy to care for. They are active fish and will provide their owners ample entertainment and joy. 

Before you run out to get your swordtails, let’s first look at everything you need about these fish. From tank size to diet to environment, behavior, and which fish you can house them with, we will provide you with all the facts and much more. So read on for the ultimate swordtail fish guide.

Swordtail fish "red and white" male with the long pointy tail that gives this fish its name
Male “Red and White” Swordtail Fish

Species Overview

Swordtails are freshwater fish initially from the Americas, naturally found in the rivers and streams of Central and Northern South America.

Swordtails share the same family, Poeciliidae, as guppies and platies.

  • Scientific Name: Xiphophorus helleri
  • Common Name: Swordtail Fish
  • Lifespan: 3 to 5 years
  • Size: 5 to 6.5 inches in length – this will depend on the sex of the fish
  • Diet: Omnivorous 

After many years of selective breeding, several different varieties have come about to produce swordtails of different colors.

The more commonly found swordtails are the Red swordtail, Kohaku swordtail, Pineapple swordtail, Red Lyretail Swordtail, Sanshoku Koi swordtail, Twinbar Solar Flare swordtail.

Female "Red and White" Swordtail Fish with a shorter round tail
Female “Red and White” Swordtail Fish

Appearance – Common “look-a-likes.”

Swordtails are on the smaller size fish and come in a wide variety of punchy colors. The most common color is deep orange red, with the males’ caudal fin often another color, commonly black or black and white. Other colors that can be encountered are orange, red, and olive. Therefore they are a common go-to choice for smaller tanks with a single species school. 

Female swordtails are often confused for a Platy or Molly fish as they are similarly shaped and size. What trips the beginner-eye is all three have flowing, fan-like tails and can be variegated in bright color and patterns. Male swordtails are more recognizable thanks to their sword-like caudal fin derived from the common name. The sword-like tail is a helpful indicator for determining the sex of swordtails. However, females are not as easy to distinguish. Once in awhile a half-moon koi betta can be confused for a female swordtail fish.

Some breeders will cross-breed swordtails with platies to create different color options – which then makes it really confusing!

Difference between platty, molly, swordtails and betta



As these are small fish, their life expectancy is short, but you will get to enjoy the company of your swordtail for about three to five years, which is not all that bad a lifespan for a small fish.

Even though these are known to be hardy fish, the longevity of your swordtail will depend on its environment. If you offer it a stress-free tank with healthy stimulation, your fish will likely live to the maximum of a good five years of age. 

Average Size

Swordtails are on the smaller side of tank fish but are also not too small. As there are different varieties of swordtails, sizes may differ. The females are larger than the males growing to a size of a maximum of 6.5 inches in length.

Male swordtails will grow to a maximum of 5.5 inches.

Behavior And Temperament

As mentioned, swordtails are considered easy fish and are often recommended as good beginner fish. Swordtails are easygoing and enjoy swimming a lot, particularly in the mid to upper parts of the tank. This is as much for their easygoing nature as for their general adaptability.

Swordtails are group fish, they do enjoy having tank mates and should have at least two companions, but they don’t specifically school like tetras do, meaning that while they will assemble together, they do not swim in union. The swordtail is a peaceful fish that will thrive in a community tank of similar fish, particularly those like their cousins, the guppies, and platies.

They are not aggressive fish, although we recommend keeping only a few males together, particularly if you have fewer females. Males can harass females, and become territorial with other males, so always keep more females to keep your fish happy and healthy.

swordtail fish male "red and black"
Male Swordtail Fish “Black and Red”

As with all fish keeping, do not keep big and small fish together, as smaller fish can end up as food. So when it comes to tank mates, opt for similarly sized fish. Remove the fry as soon as possible if any other fish are breeding, as swordtails will eat these.

Mexican tetra are not suitable tank mates because they are known to be predators of swordtails. 

Care 101

Caring for your swordtails is vital in ensuring that your fish have a long and happy life. The more contentment the fish has, the more likely it will live a long life. The first thing you will need to look at is the environment you will put your swordtails into.

Tank Size And Decoration

The general rule for tanks is the more fish, the bigger the tank will need to be. This is to ensure that each fish has sufficient space to swim. As swordtails are active fish, they will need lots of open water space, but they should also have some plants and rocks to hide in. 

We recommend tanks ranging from 20 gallons and up, mainly if you keep a group of swordtails or add other fish species. Crowded tanks will lead to disease and unhappy fish, so err on the larger side when choosing your tank.

Swordtails are middle to top swimmers meaning they will spend a lot of their time in the middle and top areas of the tank; because of this, the gravel you use at the bottom of the tank isn’t all that important, but the darker color will be more naturally realistic.

A good pump is a good idea so that there is a slow current to mimic the natural river habitat of swordtails. 

Habitat Care

Fish require healthy water conditions depending on their species. Water temperatures can vary between 64°F and 82°F, a considerable temperature range. Swordtails are adaptable, so their care requirements are much more lenient than other species.

The overall pH of the water should fall between a neutral 7pH and a slightly alkaline 8.5pH. Water hardness should sit between 12dgH and 30 dgH, which provides a significant range. 

To maintain your water health, a water filter and pump are a must-have; this will help keep the water clean and aerated, increasing the health of the swordtails. 

We recommend doing a temperature check once a day. The filter should be checked once a week and changed once a month to minimize algae growth. The hardness and pH of the water should be tested weekly.

Lighting can also be a good idea, mainly if your tank is kept in a room that does not get much sunlight. 

Swordtail Health and Disease

Like all animals, fish can get sick, and aquarium fish are also subject to disease. One problem with aquarium fish is that as aquaria are small spaces, the likelihood of the disease spreading is significant. If you notice a fish displaying unusual behavior, quarantine it immediately to reduce the risk of the disease spreading. But how do you recognize the signs of disease?

What Does A Healthy Swordtail Look Like?

A healthy swordtail will have optimal coloration, it will be bright, and the color will be even. Healthy swordtails have clear eyes and will enjoy their food, and they will also appear clean and have visible signs of disease.

What Does A Diseased Swordtail Look Like?

As swordtails are active fish, as soon as you notice a reduction in activity, it’s a good sign that something may be wrong. Conversely, if your fish start to swim strangely, busy but all over the place, they may be unwell.

Like many other pets, a loss of appetite is a definite sign of illness, as is weight loss and a loss of color. Other signs of infection are cloudy eyes, bloating and bugged-out eyes where it looks like the eyes are popping out.

Frayed fins, fungus, and spots on the body will also be a sign of distress and disease; fungus on the body may come across as the fish having a mottled appearance.

But what should you do if your fish displays any of these warning signs? Firstly quarantine your fish. We recommend keeping a small tank for emergency purposes like these. This will also make it easier to transport the ill fish to an aquatic specialist for intervention and treatment.

Another step you can take is to check your water quality; sometimes, this can be the underlying factor behind the disease. 

Always follow through with special instructions and finish anti-bacterial remedies as advised. Aquatic specialists and vets will know how to treat your fish best and may also instruct you to make changes to your tank. 

Food And Diet

Swordtails are omnivorous, so that they can eat plants and animal-based foods. Flake and pellet foods are popular and enjoyed by swordtails. Good pet stores will have an ample variety of fish foods and will be able to advise on which is best for your swordtail. 

Swordtails enjoy insects, worms, algae, and other plant materials. To keep your swordtail happy, you should ensure their diet is balanced. Frozen foods should be thawed before you feed them to your fish.

Overfeeding can be a problem, so ensure that you only feed small portions and feed what your swordtails can eat within two minutes. They can be fed up to three times a day. 

The Best Companion Fish – Do They Need To Be In Pairs?

Swordtails are gregarious fish and enjoy companionship, so they should be kept in groups to have a community. Swordtails should not be kept in pairs. Keeping just a male and female will lead to the male harassing the female, and two males may become aggressive and territorial.

The best options are to keep one male with at least three to four females; too many males with females will lead to the females being constantly harassed. Alternatively, you can keep only males but ensure at least five of them to reduce aggression. 

Can Swordtails Live With Other Species?

As swordtails are social fish, they do well with other species in the same tank. The best tank mates for swordtails are:

  • Guppies
  • Platies
  • Mollies
  • Tetras
  • Rasboras
  • Danios
  • Gouramis
  • Cory Catfish
  • Rainbowfish 


These fish have similar environmental requirements and are also social and peaceful.

When introducing new fish, do so slowly to keep your fish manageable. You should also ensure that your fish have enough room and that your tank is large enough to accommodate all species. 


Swordtails are prolific breeders and one of the easiest fish to keep for breeding. They can breed from 3 months of age, so if you do not want to produce them, stock only females or males.

As livebearers, swordtails give birth to live fry and can bear new fry almost every four to six weeks, although it can take longer, even up to a year, between spawns. 

Interestingly female swordtails can keep sperm from males in a pouch for use later on, allowing them to fertilize themselves, so even if you remove the males, don’t be surprised if your female falls pregnant again.

When females are pregnant, they will isolate themselves to one area and exhibit a larger belly. If your female shows signs of pregnancy, ensure your fish are well-fed to reduce their snacking on the fry once they are spawned. 

Once you see the fry, scoop them into a separate tank. This is for their own safety until they are bigger and less likely to be seen as food by other fish.

Optimal Conditions For Breeding

If you want to breed your swordtails, providing optimal conditions is crucial. Keep your tanks at 78°F, and keep the water quality at its best levels; this reduces stress and keeps your fish happy.

Ensuring that ammonia, pH, nitrite, and nitrate levels are safe will also help your fish. The best way to keep these levels safe is to keep your filter and tank clean.

Swordtail And Platies Breeding

Female swordfish do look remarkably like platies. As swordtails and platies are from the same family, they are often interbred. Female swordtails and male platies will interbreed, and you can expect to cross-breed if you keep both species in one tank. 

Because interbreeding is so easy if you’re looking for purebred swordtails, be sure to mention this to the pet shop when buying your fish. A good indicator is that your male swordtail should have a distinct sword-like caudal fin that a cross-bred fish is less likely to exhibit.

What Do Swordtail Fish Cost?

As swordtails are so prolific when it comes to breeding, their cost when it comes to the price of the individual fish is relatively low. Prices may rise if you opt for rarer varieties, but the average cost you can expect will range from $3 to $10

One will also need to factor in the cost of a tank, equipment like a filter, pump, light, food, plants, and other supplies. When adding this all up, if starting from scratch, you could be looking at a minimum of around $175, although prices do vary.

Wrap Up

Swordtails are fantastic beginner fish that will give their owner much joy and entertainment. They are hardy fish and easy to care for, and thanks to their social nature, they can be kept with various other fish. If you are looking to breed fish, this is a suitable species.