Swordtail fish are majestic breeds of commonly available fish, that can be sought to enrich your tanks. True to their name, they are like aquatic soldiers patrolling the water due to their unique tails. Unlike their predatory appearance, Swordtail fish are generally peaceful, with few exceptions.

Swordtail fish are a result of captive selective breeding from wild species and today, they have the distinction of having the most diverse type of visual variation among aquarium fishes.

Since Swordtail fish are live-bearing and easily adaptable to home tanks, they are said to be friendly fish for beginners and seasoned breeders alike.

Let’s make it clear that “Swordfish” and “Swordtail” are entirely different fish species that can be easily confused!

Through this article, we shall learn about their types and best practices that you can follow to make your fish parenting journey a smooth one!

General Description of Swordtail Fish

Swordtail fish are medium-sized fish that follow the general symmetry (streamline/torpedo-shaped body) of marine vertebrates. They have well-developed dorsal, caudal (tail), and anal fins, which make them very active in the water. The Swordtail generic name, Xiphophorus, is derived from the Greek word meaning, “Sword Bearer”.

Quick Species Facts
Scientific Name Xiphophorus hellerii
Common Names Multiple(based on color patterns, fin shape, etc.)
Family Poeciliidae
Origin North and Central America
Lifespan 3-5 years (in Aquarium)
Size (Length) 14 cm(male) 16 cm(female)
Type Freshwater
Swordtail Fish Morphology and Identification

Morphology and Identification

Specific identification of Swordtail fish will require a brief understanding of existing types of other varieties. The most important distinguishing factor is the color pattern, that is assigned to each particular breed/strain. Furthermore, we will go over each breed in brief so keep reading.

Pro tip: Most of the existing types of Swordtail are named by different breeders at the individual level from breeding experiments. You can be a part of it!

Dimorphism in Swordtail Fish

One reason why it is easy to breed Swordtail fish is their distinct male and female differences for identification. A breeder can plan their mating effectively in this scenario. The following characteristics can assist you in determining their gender:

  • Caudal Fin/Tail Fin- Only male Swordtail fish possess the sword-like fin on the lower side of the tail. These extraordinary features in males can extend up to two-thirds of their body length in most strains, or even more!
  • Color: It is a biological phenomenon that male members of most organisms tend to possess brighter colors compared to females. But why? Males need to grab the attention of females before finding a suitable mate. This is possible with a more radiant visual stimulus.
  • Size– Females are comparatively larger than males.
  • Dorsal Fin– The fins of males have darker shades than females. This reference can be confusing for a beginner, so one can safely forgo it.
  • Anal Fin- A Male possesses an extra fin(Gonapodium) which helps in delivering sperm to the reproductive tract of females during mating.
  • Behavioral Pattern- Males are more aggressive due to their territorial nature. This behavior is especially noticeable when more males are kept together.

Expert Tip: Sexing can be done in about 2 months of age when the fry(s) start developing sexual characters.. The above-described headings are secondary sexual characters.

Different Types of Swordtail Fish

There are numerous types/strains/breeds of Swordtail fish that are intentionally or unintentionally developed over the years. Most of the common and popular ones are briefly discussed below. It is to be noted that there can still be an exhaustive list of these fish varieties, as they can outbreed and inbreed conveniently, and produce a newer variety.

1. Wild Green Swordtail Fish

Wild Green Swordtail Fish
Wild Green Swordtail Fish

They are the most primitive breeds. Morphological features include transparent fins with a brownish streak forming a boundary line, over the entire length of the body and extending towards the tail fin/sword. The tail fin is long and appears like a highly polished sword. The majority of the other breeds are developed from this fish. One can expect to find them in the wild.

2. Neon Green Swordtail Fish

Neon Green Swordtail Fish
Neon Green Swordtail Fish

They are closely related to the original wild species of Swordtail. Only the tail fin/sword has stripes of black lining, unlike the Wild Green Swordtail.

3. Neon Swordtail Fish

Neon Swordtail Fish
Neon Swordtail Fish

The bodily pigmentation is quite similar to that of the Neon Green Swordtail fish. The difference lies in the dorsal fin, which is reddish in coloration at the base. The two edges of the tail fin/sword are covered by thick blackish shades.

4. Pineapple Swordtail Fish

Pineapple Swordtail Fish
Pineapple Swordtail Fish

This breed of Swordtail fish has its name derived from a pineapple (fruit) due to its pigment similarity. Orange is the dominant pigment present in almost every part of the body. Whereas, stripes of the red lining can be seen across the length of the body. Aesthetically, they can be a bright addition to your tanks if other tank mates present together are of duller varieties.

5. Montezuma Swordtail fish

Montezuma Swordtail fish
Montezuma Swordtail fish

They are one of the rarest types of Swordtail fish.

The dorsal fin has a peacock-like spot in the shape of a dome. The tail fin is longer than their body length (unique character). Overall, the body pigmentation is light yellowish with occasional dark spots. If you happen to own one of these strains, hopefully, you might be aware that they are not easily available and can be quite expensive. The Montezuma Swordtail fish genetic composition has more of the wild-type genes than the developed varieties. It is not surprising to find one online role-playing game called Swordtail Wizard101 based on this fish.

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6. Berlin Black Swordtail Fish

Berlin Black Swordtail Fish
Berlin Black Swordtail Fish

The eyes of these fishes are distinctly whitish visually, as their entire body is covered in black, with dotted white spots aggregating unevenly on the belly. The tail fin/sword is long and thin.

7. Berlin Koi Swordtail Fish

Berlin Koi Swordtail Fish
Berlin Koi Swordtail Fish

The body is dominated by orange, with regular black spots spread across the body. The tail fin/sword is entirely black. The dorsal fin also has dark bands.

8. Red and White Swordtail Fish/Santa Claus Swordtail Fish/Albino Koi Swordtail Fish

They are relatively easy to identify if we apply the logic of their names. The head, tail, and fin are angelic white, whereas, the bright red color divides the body from the middle, with white towards both the body extremities. They can be easily confused with Kohaku Swordtail fish.

9. Kohaku Swordtail Fish

Kohaku Swordtail Fish
Kohaku Swordtail Fish

The Red/Amber and White Swordtails have the opposite color distribution in their bodies. All their fins are translucent, with a shorter tail fin/sword compared to other varieties.

10. Swordtail Lyretail Fish

Swordtail Lyretail Fish
Swordtail Lyretail Fish

These strains of Swordtail fish can appear in different color variations. The tail fin looks similar to a lyre (a Greek musical instrument). Having a one-time look at the instrument will boost your ability to identify them easily.

11. Red Velvet Swordtail/Brick Swordtail fish

Red Velvet Swordtail/Brick Swordtail fish

The bodies of these fish are velvety or brick-shaped in texture, caused by their scales. One can expect reddish coloration on the body entirely except the eyeball. Their tail fin/sword is equal to the length of their body. One simple trick to remembering them is to consider that, if the scales are quite visible on the Swordtail body, they might belong to this strain.

12. Orange Swordtail Fish

Orange Swordtail Fish

A simple breed of Swordtail fish with a close resemblance in shape and fin structure to the Wild Green Swordtail. However, the entire body is painted orange.

13. Marigold Swordtail Fish

Marigold Swordtail Fish
Marigold Swordtail Fish

They are a lightly shaded (yellowish) color variation of the Orange Swordtail type.

14. Blood Red Swordtail Fish

Blood Red Swordtail Fish
Blood Red Swordtail Fish

They can be considered one of the easiest types to identify. Nearly 99.9% of their bodies are bright reddish. The dorsal fin is enormously extended towards the back. Interestingly, even their eyes are covered with red pigment.

15. Hi Fin Albino Swordtail Fish

Hi Fin Albino Swordtail Fish
Hi Fin Albino Swordtail Fish

These fish are almost similar to the Blood Red Swordtail in body pigmentation, but their eyes are not colored like theirs. Hi Fin Albino Swordtail dorsal fin seems to appear at least thrice the width of its body. Some shades of white patches(albino) are also distributed towards the lower half of the body.

16. Cauliflower Swordtail Fish

Cauliflower Swordtail Fish
Cauliflower Swordtail Fish

Color-associated morphology is similar to Blood Red Swordtail fish. The only characteristic feature that differentiates them from the latter is the excess growth of the dorsal fin that appears to bloom like cauliflower.

17. Black Swordtail Fish

Black Swordtail Fish
Black Swordtail Fish

This strain of Swordfish is not very different from the Berlin-type Swordtail fish. With careful observation of their tail fin/sword, it appears much shorter and thicker. Golden spots instead of white spots are also seen in them.

18. Koi Swordtail Fish

Koi Swordtail Fish
Koi Swordtail Fish

They are pretty much similar to a Koi fish in morphology, but the tail fin/sword is something that can decide if they belong to the Xiphophorus genus

19. Painted Swordtail Fish

Painted Swordtail Fish
Painted Swordtail Fish

This breed can remind us of black paint splashed against a red background. The tail fin/sword is thick and long, extending almost up to half of their body length. The dorsal fins are relatively short, broad, and seem to radiate away from their body.

20. Panda Swordtail Fish

As the name suggests, these fish are not far away from representing an aquatic version of the vulnerable Panda species! Their bodies are typically pinkish with evenly distributed streaks of black lining all over their fins. Their mouth portion has two dark bands.

21. Pineapple Candy Swordtail Fish

These strains have the characteristics of both Pineapple Swordtail fish and Kohaku Swordtail fish.

22. Red Mickey Mouse Swordtail Fish

Red Mickey Mouse Swordtail Fish

The orange overwhelmed body has a particular mouse-ear-shaped black spot at the base of the tail. One can always look for these characters to identify them.

23. Red Panda Swordtail Fish

These are somewhat similar to the Panda Swordtail except that their bodies are unequally divided between two colors, with the white covering the head portion, and some part of the belly. They have a stout black tail fin/sword.

24. Red Tuxedo Swordtail Fish

This breed has a half-black coating on the lower two-thirds of its body. The dorsal fin is triangular. They also possess a long tail fin/sword; more than half their body length.

25. Tuxedo Swordtail Fish

The major difference that differentiates them from the Red Tuxedo Swordtail is their color(gold).

26. White Swordtail Fish

These fish are humbly dressed in white coating with all their tail being transparent.

27. Red Wag Swordtail Fish

The peculiar characteristics of this fish lie in the tail fin/sword, which is distinctly black, long and, thick. These features give a wagging-like optical visualization when they swim in water. The other parts of the body are typically reddish.

28. Showa Swordtail Fish

Another complex color deviation of Swordtail fish. The dorsal and some parts of the tail are transparent, along with dark shades spread unevenly against the milky body and fins. The head retains the typical red color.

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29. Balloon Swordtail Fish

These fish strains are the result of a genetic mutation caused by a dominant gene/allele which forced the spine to curve. The resultant offspring are marked by an enlarged belly. It is important to note that these mutations do not always result in a negative deformity, but rather In the evolution of a new strain of fish that can reproduce successfully with similar features on the offspring. They are also among the rare kind of Swordtail fish

Habitat and Environment

Swordtail fish are tropical fish, inhabiting thickly vegetated habitats. In the wild, they are known to occur in freshwater, brackish (slightly saline), and marine(high salinity). The easiest description of their habitats would be to say that they are hardy and highly adaptable to different environmental parameters (temperature, salinity, pH)


Readily available in any part of the world. Swordtail fish have a short gestation period with high fecundity(the number of offspring that can be produced in a single breeding cycle). They also have the potential to become an invasive species owing to their reproductive capacity.


The price of Swordtail for sale has a tag of being among the easily affordable aquarium fish. In the US and Canada, they should cost less than $10 per piece for the majority of the varieties. The Montezuma stain can cost 5-10 times more.

Authors note: Your nearest Aquarium store will be the best source of information on this.

Swordtail Fish Care Guide

Quick Reference
Food Habits Omnivores
Feeding Frequency Twice a day
Temperament Generally Peaceful
Gestation Period 24 to 30 days
Maturity 90 days (approx.)
Reproduction Sexual & Live Bearer
Maintenance Level Low

Swordtail Fish Dieting View

It is safe to take it easy on their feeds, as these fish are omnivores and can adjust well to multiple sources of food. If you have had an aquarium before, you can be at an expert level to effectively feeding them. Pay special attention to providing higher protein content to juveniles during their growth phase. Blood worms are the best choice at this stage.

List of Food Items

  • Algae Pellets/flakes
  • Frozen/Live aquatic insects
  • Frozen/Live Blood Worms
  • Blanched Vegetables-Spinach, Carrots, Lettuce, etc.
  • Live-aquatic plants within the tanks.

How Much Should You Feed Them?

Ad libitum/unrestricted amount of feed for these fish can predispose them to gluttony and further stress them. Feeding them as much as they could complete in a couple of minutes would be a better strategy.

How Often Should You Feed Them?

During a 14 hours daylight shift, one can feed them twice(required) or thrice(if possible). Though the metabolism of these fish is high; to utilize their food within a short period, they can still forage on plant matter present in tanks for additional supplements, if sufficiently provided during tank setup.

Reproduction in Swordfish

Swordtail fish breeding can be effortlessly accomplished when basic survival amenities are provided to them. Careful selection of parents becomes a prerequisite to maintaining identical characteristics in the offspring.

Hybrids and intermixing are common when they are housed together with different varieties. Swordtail fish can successfully mate with other species of fish from the same family. i.e. Poeciliidae eg. Platy fish.

One peculiar characteristic of the fish is their ability to undergo sex reversal (female to male); under certain environmental factors and responses to the population.

Interesting Fact: Homosexual behavior is observed in Swordtail fish particularly when they undergo sex reversal.

How to Breed Them Successfully in Tanks?

  • Sex Ratio: The number of males to females in the ratio of 1:3 is considered optimum for successful mating.
  • Tank Size: Aquarium Swordtail fish require more space to move freely. They love to swim in school and form a community. If the space is inadequate for males, they tend to become aggressive toward other males.
  • Tail Fin/Sword Size: Some experimental study has indicated that Swordtail females prefer to mate with a male that has a longer tail fin/sword. Choose the male Swordtail fish that has the largest tail fin/sword.
  • Temperature: The best temperature for breeding this fish is yet to be established, but generally, the family to which they belong reproduces well in higher temperatures up to 28°C.
  • Brooder Cage: Though it is not a basic requirement, one can still make one; to present a systematic breeding system.
  • New Mates: To maintain the genetic purity of the offspring, introducing new adults of the same breed after every breeding season can retain the desired characteristics of the parents, which otherwise would deteriorate due to inbreeding depression.

Care of Fry(s) from Birth till Maturity

  • Feeding: Fry(s) of these fish are efficient feed converters. For their optimum growth, feeding them thrice a day in small quantities would be a good management practice. Opting more towards a proteinaceous diet will eliminate the chances of deficiencies in amino acids.
  • Filters: The opening of the water filter should be small enough to prevent the fry from being sucked in. A sponge filter can be used efficiently instead of the conventional type.
  • Hideout: Both the Fry(s) and adults require more space for hiding, especially if they are kept in more numbers.

Do Swordtail Fish Suffer from Diseases?

Among the diseases, they seem to appear particularly susceptible to parasitic infestation. These diseases may not result in abrupt mortality but can depress their growth and longevity. Let’s take a look at some commonly occurring diseases.

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Parasitic Disease

  • Dactylogyrus Gill Flukes Disease: It is a common parasitic infestation caused by flukes in fishes. The immature parasites enter the gills of the host and cause the organ to rot. They are the most harmful if present in large numbers. Swordtail infested with it can be prone to secondary bacterial infection.
  • Skin Flukes: These parasites usually infect the scale-less region, like fins, leading to inflammation and opacity.
  • Velvet Disease: This parasitic disease occurs mostly in marine fish, but sometimes it can infect freshwater fishes like Swordtails. The infection is characterized by the eruption of white spots on the skin layer.
  • Cryptobia Infestation: They are associated with internal parasites. Swordtail can be predisposed to this infection by deteriorating water quality, poor feed quality, and, overcrowding can predispose Swordtail to this infection. Watch out for signs of fatigue and appetite loss in them.
  • Metacercaria: These parasites are the larvae of flukes that infect the muscles and visceral organs like the brain, and liver. It is difficult to detect them normally.

Bacterial Diseases

  • Fin Rot: A common bacterial infection known to occur in most fishes, including Swordtail. It is easy to spot this disease as its symptoms are explicitly manifested in the external appearance of the fins.
  • Aeromonas infection: These bacterial agents are normal inhabitants of the fish intestine. A stress factor can reduce the resistance of the Swordtail fish and provide an environment for the bacteria to multiply rapidly. Your aquarium can suffer high mortality with its outbreak.
  • Columnaris Infection: The clinical manifestations of this disease are not specific, and can produce different signs and symptoms, ranging from ulceration of the fins to rotting of the gills.

Fungal Disease

  • Saprolegnia Infection: It is commonly called cotton wool disease as the lesions produced by these mold-like fungi resemble one another. Wool-like growth can be seen in the gills of Swordtail fish causing slow mortality.

General Treatment and Preventive Measure

The best countermeasures would be to take an anticipatory approach. Making the tank water slightly saline, with commercially available sea salt can reduce the occurrence of parasitic infestation.

Isolating the unhealthy ones in a hospital tank serves the good purpose of preventing mass outbreaks. A minimum quarantine period of 7 days should be kept for the newcomers.

Ensuring a healthy diet and checking for water quality regularly will keep them stressed-free.

Swordtail Fish Tank Setup Guide

Quick Reference
Min. Tank Size 15 gallons per fish
Water Temperature 22 °C to 28 °C
Lighting Optional
Water pH level 7-8
Brooding Chamber Optional
Swordtail Fish Tank Setup Guide

Tank Parameters

  • Plants: Live aquatic plants and green algae plants will make your aquarium lively, besides, supplying fresh oxygen and organic matter as sources of food. Shorter submerged types of plants are preferable to provide the upper half of the tank with swimming space. Tropical aquatic plants are available in most stores. Water tolerant branches of trees (Driftwood) can be placed obliquely across the tank to deliver more hiding spots for the young; in addition to PVC pipes. Keeping blocks of sea rocks/pebbles can provide better camouflage for the young and adults alike.
  • Lighting: Tropical fish are exposed to a regular cycle of day and night in the wild. Likewise, they require a similar setup for healthy adaptation. Lighting their tanks with artificial light can add more radiance.
  • Air Pump: These fish are usually kept in groups. This higher stocking density needs an abundant supply of oxygen. One can go for a second air pump when keeping such fish, or choose a higher capacity air pump.
  • Water Filter: Using a sponge-type water filter is a better choice for serving a dual purpose, i.e. usage for smaller fry(s).
  • Water Heater: Your regional climatic factors will determine if you need a water heater. Keeping in view that, Swordtail fish water temperature requirement is 22°C to 28°C, the luxury of providing one is at your behest.
  • Decor: Artificial realistic plastic plants of all colors are easily accessible on the market. Why not use decorations to outdo the colors of Swordtail fish?
  • Substrate: They are required to provide root support to live plants in the tanks.

Swordtail Tank Mates

Swordtail fish has many friends! Their calm nature makes them compatible with several fish species, as long as there is enough space to accommodate them all. Fishes like Mollies, Tetras, and Angelfish are among the many suitable tank mates.

Avoid housing them with Platy fish if you want to maintain pure breeds. Apart from fish, crustaceans like snails and shrimp can also be an addition.

Water Quality Parameters

The comfort zone for Swordtail fish can be elevated by providing a pH of  7-8 and degree of Hardness of water(dGH)@9-19.

Maintaining these values in water will make your home aquarium friendly to them.

Frequently Asked Questions

Are Swordtail fish Aggressive?

No, Swordtail fish are typically peaceful. However, sometimes the male fish can become aggressive towards other males in the presence of females. Housing more males together with fewer females in tanks makes them unfriendly.

Are Swordtail Live-bearers?

Yes, they are a classic example of live-bearer fish. The female fish carries the eggs until hatching occurs.

Can Swordtails and Platies Breed?

Yes, Swordtail fish and Platy fish belong to the same family of fish and they can interbreed to produce a hybrid.

How Long Is a Swordtail Pregnant For?

Female Swordtail fish can be pregnant for 24-30 days.

How Big Does Swordtail Fish Get?

Female Swordtail fish can grow up to 16cm, while males grow up to 14cm in length.

Finally, Should You Get Them Home?

Swordtail fish are readily accessible, though they sound peculiar and rare. Indeed, they are unique masterpieces of selective breeding, available to everyone that has the enthusiasm to keep one.

Imaginatively, they are like the wielders of swords back in ancient and medieval times but still chose to be gentle among communities. Swordtail fish can fit in almost any tank with low maintenance even if it is occupied. There is hardly any reason why they shouldn’t find a place in your aquarium.

About the Author

Dr. Vituotsolie Kiso

Vituo Kiso is a budding Veterinarian and marine species enthusiast. He did most of his internships in several Pet Clinics, Wildlife centers, and Farms across India. He has a passion for learning new things and writings besides giving consultations and treating pets.

Career Highlights:

  • Almost 3 years of experience as a Veterinary Practitioner
  • Online Pet Health Consultant
  • Verified Tutor @studypool.com

Educational Highlights:

  • Attended Rajiv Gandhi Institute of Veterinary Education and Research
  • Currently learning Geography, History, Polity, Economics, Ethics, and International Relations.

Writing Experience

  • Wrote a White Paper on ‘The Aura of Pets and Humans’ for MaxCare Pets Inc.
  • Awarded the Best Article Writing on World Environmental Day 2020 on the topic, ‘Biodiversity.’

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