Information, Freshwater fish, Live-bearers and killifish, Species, Swordtails

Green Swordtail (Xiphophorus hellerii)

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by Jason Matthews



The Green Swordtail is a popular freshwater fish species known for its distinctive, sword-like caudal fin extension. Whether you are a seasoned aquarist or just starting, this fascinating species is worth learning more about. 

In this article, we will delve into the world of the Green Swordtail, exploring its origin, appearance, size, behavior, and more. So, if you are interested in keeping this captivating species in your home aquarium, read on to discover all you need to know about the Green Swordtail.


Scientific Name: Xiphophorus hellerii
Common Names: Green Swordtail
Life Expectancy: 3-5 years
Adult Size: 10 cm


HabitatSlow-moving rivers, streams, and ponds
OriginCentral America
Care LevelEasy
Tank LevelBottom
Minimum Tank Size30 gallons
Water pH7.0-8.0
Water Temperature72-82°F (22-28°C)
Water Hardness5-15 dGH
Tank MatesCompatible with other peaceful fish, can be kept in a community tank with tetras, danios, and other livebearers

Fun Fact Corner

These fish are well-known for their impressive courtship displays and vibrant personalities. Male Green Swordtails will perform intricate dance-like displays to entice a female mate during the breeding season. Flaring their fins, changing colors, and even “dancing” in front of the female are all examples of these displays. 


The Green Swordtail is a species that originated in Central America and is known to thrive in slow-moving rivers, streams, and ponds. It is native to warm, freshwater bodies in Mexico, Honduras, Guatemala, and Costa Rica. The Green Swordtail has been introduced to several other countries for ornamental purposes, but it is still most commonly found in its native Central American range. 

Appearance & Size

The Green Swordtail is easily identified by its vibrant green coloration and distinctive caudal fin extension, which resembles a sword. Aside from its bright green coloration, the species may have black, blue, or red colors, which can add visual interest to your home aquarium. 

The Green Swordtail is a small species that can grow 10 cm long. On the other hand, the exact size of a Green Swordtail can vary depending on several factors, including the quality of care it receives and its age.


The Green Swordtail is a species with sexual dimorphism, which means that males and females can be distinguished easily. Males are typically larger and more colorful than females, with a more pronounced sword-like extension of the caudal fin. Female Green Swordtails are typically less bright and rounder in shape, lacking the distinctive sword-like extension.


This species is known for its lively and energetic behavior. Green Swordtail are social creatures who thrive in groups of three or more. This species is also an active swimmer, moving around the aquarium constantly in search of food and exploration.


The Green Swordtail is a peaceful species that does well in a community aquarium. When choosing tank mates for your Green Swordtails, it is important to consider compatibility and to avoid species that may cause harm or stress to this species. 

Good tankmates for Green Swordtails include:

  • Other peaceful community fish, such as tetras, platies, and mollies
  • Snails and shrimps, which can help control algae growth and keep the tank clean
  • Live plants, which provide shelter and help maintain water quality

Tank conditions

The Green Swordtail is a hardy species that can thrive in various aquarium environments. Provide a suitable environment for this species in your home aquarium to ensure its health and well-being. For keeping a small group of Green Swordtails, a minimum tank size of 20 gallons is recommended; however, larger tanks are better for maintaining a healthy and diverse community. 

The water temperature for the Green Swordtail should be between 72-78°F, and the pH level should be between 7.0-7.5. A high-quality filtration system is also required to maintain water quality and remove any waste produced by the fish. A strong water flow is also recommended to provide adequate oxygenation and to simulate this species’ natural environment. 


The Green Swordtail is an omnivorous species that will consume various foods in the wild and in the home aquarium. They feed on plant matter, small invertebrates, and insects in the wild. Green Swordtails should be fed a mix of high-quality dry pellets or flakes and live or frozen foods like brine shrimp, daphnia, and bloodworms. It is also recommended to supplement their diet with fresh or frozen vegetables, such as spinach or peas, to ensure proper nutrition.

Avoid overfeeding because it can cause water quality issues and harm the health of your fish. Small portions 2-3 times a day are preferable to a large amount once daily for your Green Swordtails. 


Breeding Green Swordtails can be a rewarding experience for fish owners with some breeding experience. Green Swordtails are livebearers, which means they give birth to live young instead of laying eggs.

Proper tank conditions are essential to breed Green Swordtails, including a large aquarium with plenty of hiding places and a consistent water temperature. A breeding pair of Green Swordtails should be healthy and well-fed, and it is recommended to keep only one male with several females to reduce the risk of aggression.

The female Green Swordtail will give birth to a large number of young, usually between 20 and 50, depending on the individual fish and aquarium conditions. To reduce the risk of predation by larger tank mates, provide a separate nursery tank for the young.


Diseases are a common problem with pet fish, and Green Swordtails are no exception. Fin rot, Ich, and parasitic infections are some of the most common diseases that can affect Green Swordtails.

To prevent disease spread in your Green Swordtail tank, keep good water quality and temperature, provide a balanced diet, and keep the tank free of overcrowding and stress. Regular check-ups and water changes can also aid in disease prevention.

If a Green Swordtail becomes sick, it is important to isolate the affected fish from the rest of the tank and seek veterinary assistance. Treatment options may include medications, changes to water conditions, or dietary modifications.


Jason Matthews

My name is Jason Matthews, and welcome to my website. When other kids were bragging about how their dog could sit and roll over, I was bragging about my latest Betta Fish and the cool sea castle I just added to his aquarium. 

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