Green Swordtail

Green Swordtails are hypnotizing freshwater fish, akin to Mollies and Guppies. Adorned with their striking green coloration and signature "sword" tail, they have become highly prized by aquarium enthusiasts. These amicable fish call for simple maintenance, establishing them as an outstanding option for community aquariums.

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Care DIfficulty


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Central America

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6 inches (15 cm)

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3 to 5 years

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Table of contents

Origin, Appearance, Size, and Lifespan

The Green Swordtail, or Xiphophorus helleri, often identified as the Swordtail, is a beloved freshwater fish originating from the rivers of Central America. Predominantly found in the waterways of Guatemala, Belize, and Honduras, they are accustomed to swift currents and vegetated surroundings.

In their natural habitat, Green Swordtails are frequently located in fast-flowing, deep waters rich with vegetation. This plant life acts not just as hiding places but also as a source of nourishment, while the dark riverbeds accentuate their radiant colors. These social creatures flourish in groups of at least five, but it's not rare to observe them in schools of 15 to 25 or more.

Their native environment showcases warm, moderately hard, and slightly alkaline water. The temperature generally ranges from 72 to 82 degrees Fahrenheit (22 to 28 degrees Celsius), with a pH level of 7.0 to 8.3, and water hardness between 12 to 30 dGH. To replicate a similar environment in your aquarium, strive to sustain a stable water temperature, utilize a high-quality filtration system, and integrate live plants and river rocks.

By replicating the Green Swordtail's natural habitat and ensuring optimal water conditions, you'll pave the way for your fish to enjoy a healthy and content life in your aquarium.

Green Swordtails are recognized for their lustrous green bodies, paired with a distinctive elongated tail fin. These radiant hues make them an irresistible and visually appealing addition to aquariums. Even though they are moderately sized, growing up to about 6 inches (15 cm) in length, their unique colors and energetic demeanor make them an excellent choice for those seeking a lively, colorful aquatic centerpiece. These enchanting fish delight spectators as they swiftly dart around the tank, making them a loved favorite among hobbyists of all experience levels.

With appropriate care, Green Swordtails can live up to three to five years. As social creatures, they prosper in groups and are ideally kept in schools of a minimum of five individuals. To foster their wellness and ensure a long lifespan in captivity, it's crucial to provide a densely planted aquarium with ample hiding spots, as well as a varied diet made up of high-quality flakes, pellets, and frozen foods.

Fun Facts

Having delved into the appearance and lifespan of Green Swordtails, let's now discover some intriguing facts about these appealing fish that make them a noteworthy addition to the aquarium hobby. With their standout coloration and social inclinations, Green Swordtails are replete with enchanting attributes bound to enthrall any aquarist.

  • Distinct sexual dimorphism: In the wild, Green Swordtails exhibit clear sexual dimorphism. This means males and females are distinctly different in appearance. Male Swordtails are recognized by the elongated "sword" like extension of the lower tail fin, whereas females lack this trait. This striking difference aids in the identification of sexes and plays a vital role in mating rituals.
  • Livebearers: Green Swordtails belong to the category of livebearers, which means they give birth to live fry instead of laying eggs. This unique reproductive process allows them to quickly populate a suitable environment, increasing their survival rate.
  • Swim Bladder Functionality: Unlike many fish, Green Swordtails possess a highly efficient swim bladder that enables them to remain stationary in water without sinking. This ability allows them to save energy and helps them in securing their territory.
  • Color morphs: Though the most common coloration is green, Swordtails are known for their variety of color morphs, ranging from red to black, and even multicolored variants. These different color morphs add diversity and vibrancy to any aquarium setting.
  • Schooling Behavior: Much like their Cardinal Tetra counterparts, Green Swordtails are schooling fish, preferring to move in groups. This not only provides a sense of security but also forms an enthralling visual spectacle in an aquarium. Their synchronized movements coupled with their radiant hues can morph a household aquarium into an enchanting underwater panorama.

Now that you've uncovered some captivating trivia about Green Swordtails, you'll be better prepared to appreciate their allure and complexities in your aquarium. In the subsequent section, we'll extend recommendations on tank setups, ensuring your Green Swordtails have an ideal environment to flourish and showcase their unique features.

Recommended Tank Setups

The following setups will include the fundamental components—tank, filter, heater, lighting, substrate, and more—to ensure that you can curate an ideal environment for Green Swordtails and other compatible freshwater fish species in your aquarium. As we transition from cost-effective to luxurious setups, there will also be more room for personalization, aesthetic refinement, and high-end features. Green Swordtails are sociable fish and thrive best in groups of at least five to reduce stress and foster their well-being. Usually, Green Swordtails are priced between $3 and $6 per fish, though prices can fluctuate based on aspects such as size, quality, and availability.

Budget-friendly setup (around $200):

  • Tank: 20-gallon aquarium with a hood or glass canopy ($40 - $70)
  • Filter: Hang-on-back (HOB) or sponge filter rated for 20 gallons ($20 - $40)
  • Heater: 50-100 watt adjustable aquarium heater ($15 - $30)
  • Lighting: Basic LED aquarium light ($20 - $50)
  • Substrate: Inexpensive aquarium sand or small gravel ($10 - $20)
  • Decor: A few pieces of driftwood and rocks, along with affordable live plants like Java Fern and Anubias ($20 - $40)
  • Fish: Minimum 5, maximum 10 Green Swordtails ($15 - $30)
  • 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 high-quality HOB filter rated for the tank size ($60 - $150)
  • Heater: 100-150 watt adjustable aquarium heater ($25 - $50)
  • Lighting: LED aquarium light with adjustable settings for plant growth and color enhancement ($50 - $150)
  • Substrate: Nutrient-rich aquarium substrate designed for planted tanks ($20 - $40)
  • Decor: A blend of driftwood, rocks, and live plants such as Amazon Swords, Java Fern, Anubias, and Cryptocoryne species ($40 - $80)
  • Fish: Minimum 5, maximum 15 Green Swordtails ($20 - $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

High-end setup (above $800):

  • Tank: 30-40 gallon rimless aquarium with a glass canopy ($120 - $250)
  • Filter: High-quality canister filter rated for the tank size ($100 - $250)
  • Heater: 150-200 watt adjustable aquarium heater with an external temperature controller ($40 - $80)
  • Lighting: Advanced LED lighting system with customizable settings for plant growth, color enhancement, and day/night cycles ($150 - $300)
  • Substrate: Premium aquarium substrate designed for planted tanks, with added root tabs for extra plant nutrition ($30 - $60)
  • Decor: A combination of driftwood, rocks, and live plants to create 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 Green Swordtails ($20 - $70)
  • 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

Please bear in mind that these guidelines are mere recommendations, and factors like tank mates and individual fish behaviors should also be considered when deciding how many Green Swordtails to house in your aquarium. Prices may vary depending on geographical location, brand, and availability.

Set Up Your Tank

In our earlier discussions, we looked at suggested tank setups for your Green Swordtails and their tank mates. Now, we will explore a step-by-step method for setting up your aquarium. This process will guide you through the selection of an ideal location for your tank, the cleaning and preparation of the tank, installation of essential hardware, and the cycling of water to foster a healthy environment for your fish. Furthermore, we will delve into the correct method of acclimating your Green Swordtails and other fish to their new home. By adhering to these guidelines, you're paving the way to establishing a prosperous aquatic ecosystem where your fish can thrive.

  • Step #1: Identify the most suitable location for your aquarium, ensuring it's not exposed to direct sunlight, heat sources, and draughts. Make sure the surface is even and sturdy enough to bear the weight of your filled tank. If a stand is needed for your aquarium, assemble it as per the manufacturer's directions and position the empty tank on it.
  • Step #2: Proceed by cleaning the tank with fresh water (refrain from using soap or chemicals) to eliminate dust or debris. Wipe the inside with a clean cloth or paper towel. Rinse the substrate (sand or gravel) thoroughly in a bucket until the water is clear, then evenly distribute it at the bottom of the tank, creating a slight slope towards the back for visual depth.
  • Step #3: Before you start filling the tank with water, design your aquarium's layout, including the placement of hardware like heaters and filters. This will simplify setting up and maintaining the tank in the long term. Install the heater and filter as per the manufacturer's guidelines. If you're using a sponge or under-gravel filter, position it beneath the substrate before adding water.
  • Step #4: Embellish the tank with driftwood, rocks, and plants to establish hiding spots and a visually captivating environment, ensuring there are open areas for your fish to swim freely. When decorating the tank, arrange driftwood, rocks, and plants in a way that won't cause damage or obstruct the equipment. You can also secure plants to driftwood or rocks to help them remain stationary.
  • Step #5: Fill the tank with water treated with a water conditioner if your tap water contains chlorine or chloramines. To prevent disturbing the substrate while filling, place a clean plate or plastic bag on it. Fill the tank until it's about 2/3 full. Attach the aquarium light to the hood or canopy, adhering to the manufacturer's instructions. Consider using a timer for your aquarium light to ensure a regular day and night cycle, which is crucial for fish and plants. Connect the heater, filter, and any extra equipment (air pump, CO2 system) to power sources, and place the thermometer in a location that's easy to see.
  • Step #6: Fill up the rest of the water, leaving some space between the water surface and the top of the tank for oxygen exchange. Activate the filter, heater, and other equipment. Monitor the water temperature and tweak the heater if necessary. Allow the tank to cycle for 4-6 weeks to cultivate beneficial bacteria and stabilize water parameters. During the cycling process, you can add a bacterial starter culture to expedite the establishment of beneficial bacteria in the tank. Use an aquarium test kit to keep track of ammonia, nitrite, and nitrate levels.
  • Step #7: Once the tank has cycled and the water parameters are stable, gently acclimate your Green Swordtails and other fish to the tank's conditions before adding them. Start by floating the unopened fish bag in the tank for 15-20 minutes to balance the temperature. Then, open the bag and introduce a small quantity of tank water into it. Continue adding small amounts of tank water to the bag every 5-10 minutes for a minimum of 30-60 minutes, letting the fish gradually adjust to the new water chemistry. Use a net to delicately move the fish from the bag to the tank, avoiding any unnecessary stress or exposure to the water from the bag.
  • Step #8: After all the fish have been added, establish a regular daily feeding routine, offering high-quality food in the right quantities for your specific fish species. Conduct regular water changes (20-30% every 1-2 weeks) and track water parameters using a test kit to uphold a healthy environment for your fish. Pay close attention to any signs of stress or illness in your fish, especially during the initial weeks after introduction. Be ready to intervene if necessary, such as modifying water parameters or consulting with an experienced aquarist.

By adhering to this comprehensive guide and integrating additional setup recommendations, you can create a thriving aquatic environment that enables your Green Swordtails and other fish to flourish in their new abode.

Recommended Water Parameters

The well-being of your Green Swordtails can be greatly influenced by the water conditions in your tank. The following are ideal ranges for these parameters:

  • Temperature: Aim for a water temperature of 72°F to 82°F (22°C to 28°C) to maintain a comfortable environment.
  • pH: Green Swordtails prefer slightly alkaline water with a pH range of 7.0 to 8.4.
  • Hardness: A hardness range of 12-30 dGH is suitable, as Green Swordtails thrive in moderately hard to hard water.
  • Ammonia, Nitrite, and Nitrate: The levels of ammonia and nitrite should be 0 ppm, with nitrate levels kept under 50 ppm.
  • Lighting: Moderate to high lighting is ideal for Green Swordtails, but make sure to include shaded areas for them to retreat.
  • Water movement: Green Swordtails can tolerate various water movement levels but prefer moderate to strong flow replicating their natural stream habitat.

Regularly test your aquarium water to ensure these parameters remain within the required ranges.

Routine Water Maintenance

Maintaining water quality is vital for the health of your Green Swordtails. Here is a suggested maintenance routine:

  • Weekly water changes: Each week, replace approximately 25-30% of the tank water.
  • Test water parameters: Frequently check the pH, ammonia, nitrite, nitrate, and hardness levels.
  • Use a gravel vacuum: During water changes, clean the substrate to remove any accumulated waste.
  • Dechlorinate the water: Treat any tap water with a dechlorinator before adding it to the aquarium.
  • Match temperature and pH: Ensure the replacement water matches the tank's temperature and pH to avoid causing stress to the fish.
  • Acclimate the fish: Allow your fish to adjust to any new water conditions gradually.

In addition to these routine tasks, consider the following:

  • Monitor lighting duration: Regulate the lighting period in your tank, maintaining a consistent day-night cycle of about 10-12 hours. Avoid excessive lighting to prevent algae proliferation.
  • Plant maintenance: Regularly trim live plants to maintain their health and aesthetics. Remove any dead or decaying plants to prevent water degradation.
  • Filter maintenance: Clean or replace the filter media as recommended by the manufacturer, typically every 2-4 weeks, to prevent a build-up of waste. Avoid changing all filter media at once, as it may disrupt the beneficial bacteria colony.

Diet and Feeding Schedule

Green Swordtails are omnivores, so they need a varied diet for proper nourishment. Here's what you can provide:

  • Flakes and pellets: High-quality tropical flake or pellet food should form the basis of their diet.
  • Frozen and live foods: Enrich their diet with treats like brine shrimp, bloodworms, or daphnia.
  • Vegetable matter: Include blanched spinach, zucchini, or peas for additional nutrients.
  • Feeding frequency: Offer small meals two to three times a day, taking care not to overfeed.

Stress and Diseases

Green Swordtails can become stressed due to various factors, such as inadequate water quality, aggression, or unsuitable tank conditions. Recognizing and addressing these stressors is crucial for your fish's health and well-being:

  • Identify signs of stress: Monitor your Green Swordtails for unusual behavior like hiding, lethargy, color loss, or fast breathing, which may point to stress.
  • Maintain water quality: Regularly test your aquarium water to ensure it meets the ideal parameters and perform consistent water changes to uphold a healthy environment.
  • Oversee tank mates: Ensure that your Green Swordtails aren't being bullied or assaulted by other fish, and exclude any aggressive tank mates if necessary.
  • Develop a suitable habitat: Provide ample hiding spots, appropriate lighting, and a suitably sized tank for your fish.

While Green Swordtails are generally robust, they can fall prey to some common fish diseases, such as:

  • Ich (white spot disease): A common parasitic infection resulting in white spots on the body and fins, lethargy, and loss of appetite. Treat Ich with aquarium salt or anti-parasitic medication and elevate the water temperature to around 82°F (28°C).
  • Fin rot: A bacterial infection that results in frayed or discolored fins and tail. Fin rot can be treated with a partial water change, aquarium salt, and antibacterial medication containing erythromycin or tetracycline.
  • Velvet disease: A parasitic infection leading to a yellow or brownish velvet-like coating on the fish's body. Treat velvet disease with anti-parasitic medication containing copper sulfate or formalin.
  • Swim bladder disease: A condition that impairs the fish's ability to swim upright. Treat swim bladder disease by fasting the fish and giving them blanched peas, and consider using an antibacterial medication if needed.

To prevent diseases in Green Swordtails, maintain excellent water quality, refrain from overfeeding, and offer a balanced diet. New fish should be quarantined before adding them to the main tank, and any signs of illness should be addressed promptly.


Breeding Green Swordtails can be a rewarding experience, but it requires the right setup and conditions. Follow these steps to breed Green Swordtails:

  • Step #1: Set up a suitable breeding environment with a separate 20-gallon or larger breeding tank, a pH level of around 7.0 to 8.4, and a temperature of about 72°F to 82°F (22°C to 28°C). Provide hard water (12-30 dGH) and include hiding spots like plants for the fry's safety.
  • Step #2: Choose healthy, mature male and female Green Swordtails for breeding. Maintain a ratio of one male to several females to minimize aggression and rivalry. You can identify the gender by noting their physical characteristics and behavior.
  • Step #3: Feed the breeding pair a high-protein diet of live or frozen foods for a few weeks to help them gain strength and vitality.
  • Step #4: Promote spawning by introducing the pair to the breeding tank, gradually adjusting the water temperature, and dimming the lighting. Simulate a natural day-night cycle by slowly increasing and decreasing the lighting duration in the breeding tank. Include live plants or breeding traps for the protection of the fry.
  • Step #5: Look after the fry by separating them from the adults after birth. The fry can be sensitive to light, so keep the breeding tank in a moderately lit area. They can eat crushed flake food or specially designed fry food.
  • Step #6: Watch the growth and development of the fry, and separate them by size if necessary to prevent larger fry from preying on the smaller ones.

Breeding Green Swordtails can provide a gratifying experience for aquarists. The right conditions and a good dose of patience are key to success.

Recommended Tank Mates

Here are the top 10 suggested companions for Green Swordtails:

  1. Platies
  2. Mollies
  3. Zebra Danios
  4. Harlequin Rasboras
  5. Neon Tetras
  6. Cherry Barbs
  7. Guppies
  8. Dwarf Gouramis
  9. Plecos
  10. Corydoras Catfish

Avoid housing Green Swordtails with larger, aggressive fish such as certain cichlids or predatory species, as they could cause harm to your Swordtails. Continually monitor the behavior of any new additions to make sure they don't introduce stress or hostility towards the Green Swordtails.


In summary, Green Swordtails are a charming species of freshwater fish recognized for their unique appearance and relative ease of care. These fish need specific water conditions, a balanced diet, and an appropriate habitat to thrive in captivity. With the right environment, they can live up to five years and make an outstanding contribution to any aquarium. When selecting companions for the tank, it's essential to choose peaceful and non-aggressive species to ensure a harmonious community. Breeding Green Swordtails can be a fulfilling task for experienced aquarium keepers, and patience, along with optimal conditions, are key to successful reproduction. Altogether, Green Swordtails are an eye-catching and dynamic species that can enrich any aquarium with their vibrant colors and lively behaviors.

Frequently Asked Questions

What is the ideal tank size for Green Swordtails?

Green Swordtails thrive best in a tank with a minimum capacity of 30 gallons. A larger aquarium is even more beneficial as it helps stabilize water conditions while providing plenty of room for these active swimmers.

How many Green Swordtails should be kept together?

As Green Swordtails are social fish, they do best in groups. It's recommended to keep them in a ratio of one male to several females, at least two or three, to reduce the males' aggressive courtship behaviors.

What water parameters do Green Swordtails require?

Green Swordtails prefer water temperatures between 72°F and 82°F (22°C and 28°C), a pH between 7.0 and 8.4, and moderately hard to hard water with a hardness range of 12-30 dGH.

What do Green Swordtails eat?

Being omnivorous, Green Swordtails need a varied diet. Offer them a combination of high-quality flake or pellet food, alongside live or frozen foods like brine shrimp, bloodworms, or daphnia. Vegetable matter like blanched spinach or peas is also beneficial.

Are Green Swordtails compatible with other fish?

Yes, Green Swordtails can get along with other similarly sized, non-aggressive fish species. Good tank mates include platies, mollies, danios, and smaller gouramis.

How can I distinguish between male and female Green Swordtails?

Male Green Swordtails have a long, pointed extension at the bottom of their tail fin, resembling a sword, hence their name. Females lack this feature and also tend to have a rounder body shape.

How long do Green Swordtails live?

With appropriate care and optimal tank conditions, Green Swordtails can live for 3 to 5 years.

How do I breed Green Swordtails?

Breeding Green Swordtails is relatively straightforward. They're livebearers, which means females give birth to fully formed young. Provide plenty of hiding spots for the fry, and consider a separate breeding tank to protect them from being eaten.

Do Green Swordtails require a planted tank?

While it's not strictly necessary, a planted tank is beneficial for Green Swordtails. Live plants provide shelter, contribute to better water quality, and create a natural environment similar to their native habitat.

Can Green Swordtails change color?

Yes, Green 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.