Red Swordtail

Red Swordtails are alluring freshwater species sharing close ties with other livebearers, like guppies and mollies. Sporting a vibrant red color and a distinct tail that resembles a sword, they've gained significant popularity among aquarium hobbyists. These sociable fish are relatively low-maintenance, making them an excellent addition to community tanks.

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Care DIfficulty


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Central America

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5 inches (13 cm)

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3 to 5 years

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Table of contents

Origin, Appearance, Size, and Lifespan

The Red Swordtail, or Xiphophorus helleri, is a cherished freshwater species originating from the rivers and streams of Central America. You'll commonly find them in the water bodies flowing through Honduras, Guatemala, and Mexico.

In their natural habitat, Red Swordtails are often found in moderate to fast-flowing waters rich in vegetation. These plants provide shelter and a source of food, while the light-colored riverbeds contrast beautifully with their vivid red coloration. These gregarious fish are known to thrive in groups and are usually seen in schools of various sizes.

Their natural environment features mildly hard, slightly alkaline water. The temperature typically ranges from 72 to 78 degrees Fahrenheit (22 to 26 degrees Celsius), with a pH level of 7.0 to 8.3, and water hardness between 12 to 30 dGH. To recreate a similar environment in your aquarium, maintain a stable water temperature, use an efficient filtration system, and incorporate live plants and rocks.

By emulating the Red Swordtail's natural habitat and ensuring the correct water conditions, you're paving the way for your fish to lead a healthy and contented life in your aquarium.

Red Swordtails are lauded for their bright red bodies, topped off by a unique, sword-like tail. Their exceptional colors make them a captivating and alluring presence in aquariums. Despite being small, growing up to about 4 to 5 inches (10 to 13 cm) in size, their vibrant hues and energetic disposition make them an ideal choice for hobbyists seeking a lively and visually stunning aquatic display. These engaging fish captivate onlookers as they dart around the tank, cementing their place as a beloved favorite among aquarists of all skill levels.

With suitable care, Red Swordtails can live up to three to five years. As sociable creatures, they thrive in groups and should ideally be kept in a ratio of one male to several females to avoid aggression. To ensure their longevity and well-being in captivity, it's vital to provide a well-planted aquarium with numerous hiding spaces, as well as a varied diet comprising high-quality flakes, pellets, and live foods.

Fun Facts

Having explored the appearance and lifespan of Red Swordtails, let's move on to some intriguing tidbits about these vibrant fish that make them a star attraction in the aquarium world. With their stunning coloration to their distinct behavior, Red Swordtails are packed with features that will delight any aquarist.

  • Livebearers: Uniquely, Red Swordtails are livebearers, meaning they give birth to fully-formed young rather than laying eggs. This trait not only adds an exciting dimension to your aquarium life but also simplifies the breeding process for hobbyists.
  • Natural Swimmers: Red Swordtails are robust swimmers, thanks to their long, sword-like tails. In their natural environment, these tails help them navigate swiftly against currents, enabling them to inhabit a diverse range of water bodies.
  • Males vs. Females: One fascinating fact about Red Swordtails is that only males possess the characteristic "sword" tail. Females, on the other hand, have shorter, rounded tails. This sexual dimorphism makes it easy to distinguish between the sexes in your tank.
  • Color Changing Ability: Similar to Cardinal Tetras, Red Swordtails can also change their color intensity in response to their environment, health, or mood. When they're stressed or in poorly lit conditions, their colors might appear dull. Conversely, when they feel safe and healthy, their colors become more vibrant, adding a splash of color to any aquarium.
  • Community-Oriented Behavior: Red Swordtails are highly social and prefer to live in community setups. Their harmonious swimming patterns and stunning colors create a dynamic visual spectacle in the aquarium.

Now that you're familiar with some compelling facts about Red Swordtails, you'll be better prepared to enjoy their vibrant features and unique behaviors in your aquarium. In the next section, we'll delve into tank setup recommendations, ensuring your Red Swordtails have an ideal environment to flourish and exhibit their radiant charm.

Recommended Tank Setups

The below setups have been curated with the primary elements like tank, filter, heater, lighting, substrate, and more, enabling you to construct an ideal habitat for Red Swordtails and other companionable freshwater fish species in your aquarium. As you graduate from cost-effective to premium setups, you will also have increased flexibility for personalization, visual appeal, and high-tech features. Red Swordtails are sociable fish and should be maintained in groups of a minimum of five to reduce anxiety and promote their welfare. Typically, Red Swordtails cost between $3 and $5 per fish, although costs can fluctuate due to variables such as size, quality, and supply.

Budget-friendly setup (around $200):

  • Tank: 20-30 gallon aquarium with a hood or glass canopy ($40 - $80)
  • Filter: Hang-on-back (HOB) or sponge filter suitable for 20-30 gallons ($20 - $40)
  • Heater: 50-100 watt adaptable aquarium heater ($15 - $30)
  • Lighting: Basic LED aquarium light ($20 - $50)
  • Substrate: Affordable aquarium sand or small pebbles ($10 - $20)
  • Decor: A couple of driftwood and stone pieces, accompanied by low-cost live plants like Java Fern and Anubias ($20 - $40)
  • Fish: Minimum 5, maximum 10 Red Swordtails ($15 - $50)
  • Thermometer: $3 - $10
  • Substrate Vacuum: $10 - $25
  • Fish Net: $2 - $10
  • Algae Scraper or Magnetic Cleaner: $5 - $20
  • Siphon and Bucket: $15 - $30
  • Test Kit: $15 - $50
  • Fish Food: $5 - $20
  • Water Conditioner: $5 - $15

Mid-range setup (around $400 - $650):

  • Tank: 30-40 gallon aquarium with a hood or glass canopy ($60 - $120)
  • Filter: Canister filter or premium HOB filter rated for the tank size ($60 - $150)
  • Heater: 100-150 watt adaptable aquarium heater ($25 - $50)
  • Lighting: LED aquarium light with flexible settings for plant development and color improvement ($50 - $150)
  • Substrate: Nutrient-rich aquarium substrate designed for plant-filled tanks ($20 - $40)
  • Decor: A combination of driftwood, rocks, and live plants like Amazon Swords, Java Fern, Anubias, and Cryptocoryne species ($40 - $80)
  • Fish: Minimum 5, maximum 15 Red Swordtails ($25 - $75)
  • Thermometer: $3 - $10
  • Substrate Vacuum: $10 - $25
  • Fish Net: $2 - $10
  • Algae Scraper or Magnetic Cleaner: $5 - $20
  • Siphon and Bucket: $15 - $30
  • Test Kit: $15 - $50
  • Fish Food: $5 - $20
  • Water Conditioner: $5 - $15

High-end setup (above $800):

  • Tank: 40-50 gallon rimless aquarium with a glass canopy ($120 - $250)
  • Filter: Superior quality canister filter suitable for the tank size ($100 - $250)
  • Heater: 150-200 watt adjustable aquarium heater with an external temperature controller ($40 - $80)
  • Lighting: Sophisticated LED lighting system with customizable settings for plant growth, color enhancement, and day/night cycles ($150 - $300)
  • Substrate: Top-quality aquarium substrate for planted tanks, supplemented with root tabs for extra plant nutrition ($30 - $60)
  • Decor: A mix of driftwood, rocks, and live plants to form a natural aquascape, featuring plant species such as Amazon Swords, Java Fern, Anubias, Cryptocoryne species, and carpeting plants like Dwarf Hairgrass or Monte Carlo ($60 - $150)
  • Fish: Minimum 5, maximum 20 Red Swordtails ($25 - $100)
  • Thermometer: $3 - $10
  • Substrate Vacuum: $10 - $25
  • Fish Net: $2 - $10
  • Algae Scraper or Magnetic Cleaner: $5 - $20
  • Siphon and Bucket: $15 - $30
  • Test Kit: $15 - $50
  • Fish Food: $5 - $20
  • Water Conditioner: $5 - $15

Do bear in mind that these figures are just guidelines, and you should take into account other elements like tank companions and individual fish behaviors when deciding the number of Red Swordtails to house in your aquarium. Prices may vary based on location, brand, and availability.

Set Up Your Tank

In our previous discussion, we highlighted the suggested aquarium setups for your Red Swordtails and other companion fish. With this knowledge in mind, we can now delve into the specifics of establishing your aquarium. This process involves selecting the ideal location, preparing and cleaning the tank, installing vital equipment, and preparing the water to ensure a healthy habitat for your fish. We will also touch on the correct method of acclimating your Red Swordtails and other fish to their new environment. Adhering to these guidelines will pave the way for a vibrant aquatic ecosystem for your fish to thrive in.

  • Step #1: The first thing you need to do is find the perfect spot for your aquarium. This spot should be away from direct sunlight, sources of heat, and drafts. Ensure the chosen surface is level and sturdy enough to support the weight of your filled tank. If a stand is needed for your aquarium, assemble it following the manufacturer's guidance and position the empty tank on top.
  • Step #2: After choosing the right spot, it's time to clean your tank. Rinse it with clean water (avoid using soap or other cleaning agents) to get rid of any dust or debris. Dry the inside with a clean cloth or paper towel. Rinse your chosen substrate (either sand or gravel) in a bucket until the water runs clear. Spread the rinsed substrate evenly at the bottom of the tank, sloping it slightly towards the back for an illusion of depth.
  • Step #3: Before adding water to your tank, map out the layout of your aquarium, considering the placement of equipment such as heaters and filters. This forethought will simplify the setup and future maintenance of your aquarium. Install your heater and filter according to the instructions provided by the manufacturer. If you've opted for a sponge or under-gravel filter, position it under the substrate before adding water.
  • Step #4: Now, it's time to decorate your tank. Arrange driftwood, rocks, and plants in a manner that creates hiding spots for your fish and is visually pleasing. Ensure that you also provide open swimming spaces for your Red Swordtails. While arranging these decorations, be mindful not to damage or obstruct any equipment. You might also want to anchor plants to driftwood or rocks to keep them in place.
  • Step #5: Begin filling your tank with water treated with a water conditioner, especially if your tap water contains chlorine or chloramines. While filling the tank, place a clean plate or plastic bag on the substrate to prevent it from being disturbed. Fill the tank until it's about 2/3 full. Attach the aquarium light to the hood or canopy as per the manufacturer's guidelines. To maintain a consistent day and night cycle for your fish and plants, consider using a timer for your aquarium light. Connect your heater, filter, and any additional equipment such as an air pump or CO2 system to power sources. Place the thermometer in a location that's easily visible.
  • Step #6: Top up the water, leaving some space between the water surface and the top of the tank for oxygen exchange. Turn on the filter, heater, and other equipment. Monitor the water temperature, adjusting the heater as necessary. Allow the tank to cycle for 4-6 weeks to foster the growth of beneficial bacteria and stabilize the water parameters. You can also use a bacterial starter culture during this process to expedite the growth of beneficial bacteria. Regularly monitor ammonia, nitrite, and nitrate levels using an aquarium test kit.
  • Step #7: After your tank has successfully cycled and the water parameters are stable, you can slowly acclimate your Red Swordtails and other fish to the tank conditions. Start by floating the unopened fish bag in the tank for about 15-20 minutes to equalize the temperature. Then, open the bag and gradually add small amounts of tank water to it every 5-10 minutes for at least 30-60 minutes, thus letting the fish adjust to the new water chemistry. Use a net to gently move the fish from the bag to the tank to minimize stress and prevent exposure to the water from the bag.
  • Step #8: Once all your fish have been added, establish a regular feeding schedule, providing high-quality food that's suitable for your specific fish species. Regular water changes (about 20-30% every 1-2 weeks) are crucial, as is monitoring water parameters using a test kit. Closely observe your fish for any signs of stress or sickness, especially during the initial weeks after introduction. If necessary, be ready to take corrective actions, such as adjusting water parameters or seeking advice from an expert aquarist.

By adhering to this step-by-step guide and applying the aforementioned setup advice, you'll be able to create a thriving aquatic habitat that caters to the needs of your Red Swordtails and other fish.

Recommended Water Parameters

For your Red Swordtails to thrive, it's important to maintain the ideal water parameters in your aquarium. Here's what you should aim for:

  • Temperature: The water should be kept between 64°F and 82°F (18°C and 28°C) for optimal comfort.
  • pH: Aim for a pH of 7.0 to 8.4, as they prefer slightly alkaline water.
  • Hardness: Moderately hard to hard water (12-30 dGH) is ideal.
  • Ammonia, Nitrite, and Nitrate: Maintain ammonia and nitrite levels at 0 ppm, and keep nitrate levels below 20 ppm.
  • Lighting: Moderate to bright lighting is fine, but provide plants or decor for shaded areas.
  • Water movement: A moderate water flow is preferable to mirror their natural habitat.

Ensure to regularly test your aquarium water and conduct necessary water changes to maintain a stable environment.

Routine Water Maintenance

Routine water changes are essential for a healthy Red Swordtail aquarium, helping to remove excess nutrients, toxins, and waste. Here's a suggested routine:

  • Weekly water changes: Swap out 25-30% of the tank water every week.
  • Test water parameters: Regularly check pH, ammonia, nitrite, nitrate, and hardness.
  • Use a gravel vacuum: Utilize this tool to clean the substrate during water changes.
  • Dechlorinate the water: Treat tap water with a water conditioner before introducing it to the aquarium.
  • Match temperature and pH: Ensure the new water is similar in temperature and pH to the tank water.
  • Acclimate the fish: Allow your fish to adjust to new conditions after water changes.

In addition to consistent water maintenance, bear in mind the following:

  • Monitor lighting duration: Ensure a consistent 10-12 hour photoperiod. Excessive light can encourage algae growth.
  • Plant maintenance: Trim live plants regularly for their health and appearance. Remove any dead leaves or plant matter to prevent water quality issues.
  • Filter maintenance: Clean or replace the filter media as per the manufacturer's recommendation, typically every 4-6 weeks. Avoid replacing all filter media at once to prevent disrupting beneficial bacteria and affecting water quality.

Diet and Feeding Schedule

Red Swordtails are omnivores, requiring a varied diet. Here are some feeding guidelines:

  • Flakes and pellets: Provide high-quality flake or pellet food suitable for livebearers.
  • Frozen and live foods: Treat your fish with brine shrimp, bloodworms, or daphnia occasionally.
  • Vegetable matter: Incorporate blanched spinach, peas, or zucchini for added nutrition.
  • Feeding frequency: Feed moderate portions once or twice a day, being cautious not to overfeed.

Stress and Diseases

Red Swordtails may become stressed due to poor water quality, aggression, or inadequate tank conditions. Recognizing and addressing these stressors is essential for their well-being:

  • Watch for stress signs: Look out for unusual behavior such as hiding, sluggishness, loss of color, or rapid breathing, which could signify stress.
  • Check water quality: Test your aquarium water to ensure it aligns with ideal parameters and perform regular water changes to foster a healthy environment.
  • Monitor tank mates: Ensure your Red Swordtails are not harassed by other fish. Remove any aggressive tank mates if necessary.
  • Create a suitable habitat: Provide abundant hiding spots, appropriate lighting, and a suitably-sized tank.

Red Swordtails can be susceptible to certain common fish diseases, such as:

  • Ich (white spot disease): A common parasitic infection causing white spots on the body and fins, lethargy, and appetite loss. Treat Ich with aquarium salt or anti-parasitic medication.
  • Fin rot: A bacterial disease causing frayed or discolored fins and tail. Treat fin rot with a partial water change, aquarium salt, and antibacterial medication.
  • Velvet disease: A parasitic infection causing a gold or rust-colored dusting on the fish's body. Treat velvet disease with anti-parasitic medication.
  • Swim bladder disease: A condition resulting in difficulty swimming upright. Treat swim bladder disease by fasting the fish and offering them blanched peas, with antibacterial medication as a secondary option.

Prevent disease by maintaining excellent water quality, providing a balanced diet, and avoiding overfeeding. New fish should be quarantined before being introduced to the main tank, and signs of illness should be promptly addressed.


Breeding Red Swordtails can be an enjoyable undertaking. Here's how to do it:

  • Step #1: Prepare a suitable breeding environment in a separate 10-20 gallon tank. Keep the pH level around 7.0-8.4, and the temperature about 75°F (24°C). Maintain hard water (12-30 dGH) and include plants for the female to hide and to provide areas for the fry.
  • Step #2: Choose a healthy, mature pair for breeding. Typically, females are larger and less colorful than males.
  • Step #3: Feed the chosen pair a high-protein diet of live or frozen foods for several weeks to stimulate breeding.
  • Step #4: Introduce the pair to the breeding tank. Females will give birth to live fry after a gestation period of around 28 days. Provide plenty of hiding spots for the fry to avoid being eaten by the adults.
  • Step #5: After the female gives birth, move her back to the main tank to prevent her from eating the fry. The fry can be fed finely crushed flake food or specially designed fry food.
  • Step #6: Monitor the growth of the fry and separate them by size if necessary to prevent cannibalism.

Breeding Red Swordtails can provide a rewarding experience and an opportunity to learn more about the life cycle of this beautiful species.

Recommended Tank Mates

These are the top 10 suitable companions for Red Swordtails:

  1. Mollies
  2. Platies
  3. Tetras
  4. Corydoras
  5. Plecos
  6. Guppies
  7. Ghost Shrimp
  8. Mystery Snails
  9. Danios
  10. Angelfish

Be sure to steer clear of large, aggressive fish such as oscars, large cichlids, or predatory species, as they may pose a threat or cause stress to the Red Swordtails. Always monitor the behavior of newly introduced fish to ensure they do not create conflict or induce aggression amongst your Red Swordtails.


In essence, Red Swordtails are a vibrant freshwater fish species recognized for their distinctive tail shape and easy upkeep. These fish require specific water parameters, a balanced diet, and an appropriate environment to prosper in captivity. With adequate conditions, they can live up to 3-5 years and serve as a brilliant addition to any aquarium. Choosing peaceful and non-aggressive species as tank mates is crucial for maintaining a harmonious community. Breeding Red Swordtails might pose a challenge, but it can be an enlightening and gratifying experience for those with enough patience and the right conditions. Overall, Red Swordtails are a beautiful and lively species that can amplify any aquarium's charm with their bright colors and energetic disposition.

Frequently Asked Questions

What is the ideal tank size for Red Swordtails?

Red Swordtails prefer spacious environments, so a 29-gallon tank is a minimum suggested size for a pair. A larger tank is even better, providing ample swimming space and facilitating a stable aquatic environment.

How many Red Swordtails should be kept together?

Red Swordtails are social fish that thrive when kept in pairs or small groups. It is important to keep a balanced male to female ratio (preferably one male to two females) to prevent aggression and stress.

What water parameters do Red Swordtails require?

Red Swordtails thrive in water temperatures between 64°F and 82°F (18°C and 28°C), a pH between 7.0 and 8.4, and moderately hard to hard water with a hardness between 12 and 30 dGH.

What do Red Swordtails eat?

Red Swordtails are omnivorous and require a diverse diet. Feed them a combination of high-quality flake or pellet food, live or frozen foods such as brine shrimp and bloodworms, and vegetable matter.

Are Red Swordtails compatible with other fish?

Yes, Red Swordtails are generally peaceful and can coexist with other non-aggressive fish of similar size. Ideal tank mates include platies, mollies, tetras, and corydoras catfish.

How can I differentiate between male and female Red Swordtails?

Male Red Swordtails are usually smaller and more colorful than females and possess the characteristic 'sword' extension on their tail. Females are larger, less colorful, and lack the 'sword.'

How long do Red Swordtails live?

With optimal tank conditions and proper care, Red Swordtails can live for about 3 to 5 years.

How do I breed Red Swordtails?

Breeding Red Swordtails involves providing a stress-free environment, a balanced diet, and an appropriate ratio of males to females. Females will give birth to live fry after a gestation period of around 28 days.

Do Red Swordtails require a planted tank?

While not strictly necessary, a planted tank can greatly benefit Red Swordtails. Live plants provide hiding spots, help to maintain water quality, and create a more natural environment that closely resembles their native habitat.

Can Red Swordtails change color?

Yes, Red Swordtails can experience color changes due to factors like stress, illness, or changes in water conditions. If your Green Swordtails show a loss of color, it's essential to check the water parameters and monitor their health closely.