Xiphophorus Pygmaeus – Detailed Guide: Care, Diet, and Breeding

Xiphophorus Pygmaeus – Detailed Guide Care, Diet, and Breeding

Xiphophorus pygmaeus, commonly known as the Pygmy Swordtail, earned its name because of its tiny size. In fact, this fish is one of the smallest among all species of swordtails.

Keeping Xiphophorus pygmaeus poses some difficulty for beginners because this species is less tolerant of environmental changes. In addition, these fish require a current, lots of oxygen, hard water, and pristine water quality overall.

In this article, I will summarize everything known about Xiphophorus pygmaeus, including its preferences for care, diet, and breeding.

Quick Notes about Xiphophorus Pygmaeus

Name Xiphophorus pygmaeus
Other Names Dwarf Swordtail and Slender Pygmy Swordtail
Scientific Name Pygmy Swordtail
Water type Freshwater water
Tank size (minimum) 10 gallons (~40 liters)
Keeping Medium
Breeding Easy-medium
Size 1 – 1.6 inches (2.5 – 4 cm)
Optimal Temperature 71 – 78°F (22 – 26°С)
Optimal PH 7.0 – 8.0 
Optimal GH 8 – 20 
Dwellers Top-Middle
Nitrate Less than 80
Diet Omnivore
Temperament Peaceful
Life span up to 5 years
Color Form Yellow, blue

Etymology of Xiphophorus Pygmaeus

The genus name “Xiphophorus” is derived from two Greek words: “Xiphos”, meaning “Sword”, and “Phoros” meaning “Bearer or Carrier”.

The species name “Pygmaeus” is of Greek origin, meaning “Dwarf or tiny”. It is used to show the miniature size of this fish.

Note: In 1943, Xiphophorus pygmaeus received its name because, during its description by Hubbs and Gordon, they observed all known males of this species to be smaller in size compared to males of closely related swordtail species.

Distribution of Xiphophorus Pygmaeus

Xiphophorus Pygmaeus – Detailed Guide Care, Diet, and Breeding DistributionXiphophorus pygmaeus is a freshwater species endemic to Mexico and occurs exclusively in the Rio Axtla and its tributaries (Rio Tancuilin and Rio Huichihuayan) within the Pánuco River system.

Note: According to the studies, this species is abundant in Rio Huichihuayan, less common in the lower 9 km of Rio Tancuilin and the upper 5 km of Rio Axtla.

Habitat of Xiphophorus Pygmaeus

These fish inhabit clear, shallow (less than 3 ft or 1 m), well-shaded, moderate to fast spring-fed streams, preferring undercut banks and dense stands of submerged aquatic vegetation.

These fish inhabit clear, shallow waters (less than 3 feet or 1 m deep), within well-shaded and moderately to fast-flowing spring-fed streams. They also prefer areas with undercut banks and abundant submerged aquatic vegetation.

Description of Xiphophorus Pygmaeus

The Pygmy Swordtail is a very small freshwater fish belonging to the family Poeciliidae. The typical adult size of the Pygmy Swordtail ranges from 1 to 1.5 inches (2.5 to 3.8 centimeters) in length.

Size. On average, the size of males ranges from approximately 1 to 1.2 inches (approximately 2.5 to 3 cm). In rare cases, males can reach almost 1.4 inches (3.8 cm ), but these are exceptions, as experiments have shown that they do not pass on the corresponding gene responsible for size to their offspring. Females are slightly larger than males. On average, their size ranges from 1.2 to 1.5 inches (29 – 40 mm).

Note: Besides this species, there are also Xiphophorus continens and Xiphophorus multilineatus, which are classified as smaller swordtails.

Xiphophorus Pygmaeus – Detailed Guide Care, Diet, and Breeding Color genotypesColoration. The main coloration is greyish-brown. The belly is lighter in color. In this species, there are no vertical bars. In females, there is often one bold lateral line running from the eye along the body.

Color genotypes. There are two genotypes of males in this species:

  • yellow
  • blue.

In reality, they are called “blue” only as a convention, because their color is not actually blue, but rather has brown nuances (this is their wild color). As for the yellowish ones, among them, there can also be brightly colored individuals, which is why some researchers consider them as a third type, but this has not yet been recorded in scientific literature.

Females are duller blue-gray with a yellow tint on the dorsal side.

Swords. Xiphophorus pygmaeus has a highly reduced or no sword. It may sound strange but in this species, most males do not exhibit a prominent sword-like structure, only a smaller proportion of males do possess such a feature. At the base of the caudal fin, there can be a very short sword which is generally less than 0.08 inches (2 mm) but never more than 0.3 inches (8 mm). Additionally, the sword does not have black edging.

Fins. The dorsal fin of this species is relatively small, both in terms of its height and length at the base. The fin is transparent, with a subtle black border and a faint black stripe that runs one-third of the way up the fin.

Lifespan of Xiphophorus Pygmaeus

Currently, there is no data available on the maximum lifespan for Xiphophorus pygmaeus in the wild.

However, in aquariums, Pygmy Swordtails typically live 3 – 5 years, if appropriately cared for.

It is important to provide them with a suitable environment, a balanced diet, and regular maintenance to ensure their well-being and longevity.

Typical Behavior of Xiphophorus Pygmaeus

Temper:

Pygmy Swordtails are peaceful fish. Although males establish dominance hierarchies and compete for access to females, it was noticed that their agonistic interactions with each other almost never escalate into physical contact.

It is generally recommended to keep only one male swordtail with several females or to keep a group of males with plenty of space and hiding places to reduce such behavior.

Unlike their larger cousins, even if stressed they usually do not nip at the fins of long-finned or slow-moving fish. They are pretty shy and can be easily scared off.

Activity:

Pygmy Swordtails are relatively active and lively fish if there are no fish that can bully them.

They enjoy exploring their environment and are particularly fond of areas with dense vegetation or places to hide.

They are also good jumpers. So, you need to cover the tank or lower the water level by at least a few inches.

Sociality:

Swordtails are social fish. Therefore, it is recommended to keep them in groups of at least 3-4 individuals to ensure their well-being and encourage natural behavior. Ideally, you need to have at least 3-4 females per 1 male.  

Being in a group allows them to engage in natural behaviors, which will reduce stress and improve their overall well-being.

Note: Do not introduce just a pair (male and female) into a tank. The female would be constantly harassed and pursued by the male. It will exhaust, stress, and weaken the female.

Placement in Tank:

Pygmy Swordtails tend to occupy the upper and middle sections of the tank, with occasional visits to the bottom. However, they don’t particularly favor the bottom area.

Features:

  • Social: Yes
  • Activity: Moderate
  • Placement: Top and middle dwellers
  • Peaceful: Yes
  • Nippers: No
  • Jumpers: Yes

Feeding Xiphophorus Pygmaeus

This species is a diurnal omnivore. Pygmy Swordtails are not picky eaters, they will happily consume dry and freeze-dried foods such as flakes, pellets, and crisps as long as it is adapted to their mouth size.

In the aquarium, the Swordtails can be fed with a wide variety of meals such as:

How to feed Xiphophorus Pygmaeus:

This is a diurnal species, so it is better to feed them in the morning. Use the «five-minute rule».

Ideally, feed Pygmy Swordtails in small portions (at least 2 times a day) rather than a large amount once a day. This mimics their natural feeding behavior and helps prevent overfeeding and digestive issues.

Features:

  • Diet Type: Omnivore
  • Food Preference: Meat
  • Feeding Frequency: Daily

Are Xiphophorus Pygmaeus Plants Safe?

Yes, Pygmy Swordtails are completely plant safe. They will not eat any healthy plants in the tank. This specie does not eat living plant material.

Keeping and Caring for Xiphophorus Pygmaeus

To ensure the well-being of Pygmy Swordtails, it is essential to understand their needs and create an environment that closely resembles their natural habitat.

Pygmy Swordtails are pretty delicate fish. They are particularly sensitive to ammonianitrites, or nitrates.

Therefore, it is highly recommended to avoid introducing them as the initial inhabitants immediately after the completion of the aquarium cycling process. It is recommended to wait for at least a few weeks to allow the establishment of a stable and balanced environment.

Tank size:

Despite their small size, a group of 6-8 fish will require an absolute minimum aquarium size of 10 gallons (40 liters).

There are a couple of important reasons for that, such as:

  • These fish are pretty active and move around a lot.
  • If you have several males, there will be aggression because of limited space.
  • It will be hard to create current in small tanks.
  • Maintaining water balance and parameters is easier in larger aquariums because they provide a larger volume of water.
  • This allows for more stable water conditions and dilutes any potential fluctuations in water chemistry.

Important: Pygmy Swordtails are jumpers! So, it is imperative to take measures, for example: using a tank cover, lowering the water level, and using floating plants, which is essential to ensure their safety.

Related article:

 Water Parameters:

Temperature: Pygmy Swordtails require temperature conditions of 71 – 78°F (22 – 26°С).

pH: These fish also prefer slightly alkaline conditions. The ideal pH range should be between 7.0 – 8.0.

Hardness: The recommended general hardness (GH) range for these fish is between 8 to 20 dGH. They do not like soft water.

Lighting:

Pygmy Swordtails thrive in subdued lighting.

However, if you decide to keep these fish in planted tanks, lighting should be adapted to the needs of plants.

Related articles:

Water flow:

In their natural habitat, Pygmy Swordtails inhabit shallow waters where the current is moderate or relatively fast. They do like to swim in it.

Although it is possible to keep these fish in an aquarium without a current, it will not significantly affect them too much. Therefore, it is still advised to create a current if you want to offer the ideal conditions.

Aeration:

Aeration and water flow often go hand in hand.

Keep in mind that a powerful filtration system needs to be in place to properly aerate the aquarium water and maintain a high level of oxygenation as well. The fish enjoys water with a rich oxygenation

Air stones and other aeration decors can be added to the tank for more oxygenation.

Related article:

Decorations and Plants:

Pygmy Swordtails are shy and will appreciate plenty of hiding places, such as caves, driftwood, tall plants, and floating plants.  They may retreat to these hiding places if they feel threatened or stressed.

It is not recommended to keep these fish in open aquariums. The open layout proves unsettling for these timid fish.

NoteDwarf water lettuceFrogbitDuckweed, and other floating plants are excellent at hiding light and providing these fish with the lighting they prefer.

Related articles:

Breeding Xiphophorus Pygmaeus

Breeding and reproduction of Pygmy Swordtails is a relatively easy process, similar to other livebearers. For breeding purposes, it is recommended to keep a ratio of 1 male to 3-4 females.

Maturity:

This species reaches maturity at around 5-6 months of age.

  • Males are considered mature when the gonopodium is fully formed (third, fourth, and fifth anal fin rays elongated and fused) and pectoral fins fully pointed.
  • Females can be identified by a brood spot.

Mating:

Interesting facts:

  • In this species, there is no courtship. Even abnormally large males exhibit only chase behavior (a detailed description of chasing behavior is here). A male performs a parallel approach when he swims closely parallel to the female.
  • According to the study, with lower predation risk, females showed mating preferences for blue males, but yellow males dominated in agonistic interactions and were more aggressive in pursuing females. However, females from the population characterized by high predation risk showed no mating preferences for blue males.
  • There is no sexual selection by females.
  • Females have a preference for heterospecifics over
  • Females also prefer the large courting males of Xiphophorus nigrensis to their own small, non-courting males. Given a chance, females prefer larger conspecifics to small conspecifics.
  • Xiphophorus pygmaeus can easily hybridize and produce viable offspring with other Xiphophorus species (such as cortezi and X. nigrensis).

Fertilization:

Fertilization is internal. Males use a sexual organ called a gonopod to introduce sperm into the female’s oviduct.

Gestation:

Depending on the temperature, the gestation period is 3-4 weeks.

Fecundity:

Xiphophorus pygmaeus is not a prolific breeder as some sources say. This is probably because of their small size and relatively large fry. On average, females give birth only to 3-4 fry.

Fry:

The newly hatched fry is pretty large (0.24–0.28 in or 6-7 mm). They require microscopic food such as infusoria, moina, artemia, or specialized liquid or powdered products.

In the wild, Xiphophorus pygmaeus almost never see their offspring, as the fry are immediately swept away by the currents.

In aquariums, however, the parents may mistake the fry for food. The good thing though is that this species will not deliberately hunt down and chase their fry. Therefore, in most cases, the fry will survive. Nonetheless, to ensure the survival of the fry, the aquarium should be either densely planted with aquatic plants or the fry should stay in a separate tank for at least a month.

Xiphophorus Pygmaeus and Suitable Tankmates

Pygmy Swordtails are friendly fish which is suitable for smaller tanks but be sure of it that they still have sufficient swimming space for them. 

When choosing tankmates for this species, it is important to consider their size, behavior, and compatibility with other species in the aquarium. For example, if you have territorial fish that like to assert control over the aquarium, it’s best to avoid keeping Pygmy Swordtails with them.

Fish:

If you still decide to keep this species in community tanks, its tank mates should be all small fish species that are not big enough to eat or harass them. Ideally, you need to choose species that prefer warm and slightly alkaline aquarium water, such as:

NeonsEndlers, Danio Rerio, Guppy, Pygmy CoryLeast Killifish, Swordtails, Ghost Glass Catfish, Butterfly Hillstream Loach, Borneo Sucker, Medaka Ricefish, etc.

Shrimp:

It is possible to keep Pygmy Swordtails with dwarf shrimp. These fish have very small mouths to be a threat to adults or even juvenile shrimp.

However, newly-hatched shrimp are tiny enough (0.03 inches or 2 mm) to fit in their mouth. So, there is always a chance that they might snack on them from time to time.

Note: Shrimplets that are a few weeks old will be too big for them to eat.

Snails:

They are compatible with any freshwater snail

Avoid:

Related article:

In Conclusion

Pygmy Swordtails are not as popular as common Swordtails. As a result, many people may miss out on the opportunity to enjoy the unique beauty and personality of this tiny species.

This small, colorful fish can be a highlight in many peaceful community aquariums, especially in planted tanks.

References:

  1. Ryan, M. J., and B. A. Causey. ““Alternative” mating behavior in the swordtails Xiphophorusnigrensis and Xiphophoruspygmaeus (Pisces: Poeciliidae).” Behavioral Ecology and Sociobiology24 (1989): 341-348.
  2. Hankison, Shala J., and Molly R. Morris. “Sexual selection and species recognition in the pygmy swordtail, Xiphophoruspygmaeus: conflicting preferences.” Behavioral Ecology and Sociobiology51 (2002): 140-145.
  3. Kingston, Jennifer J., Gil G. Rosenthal, and Michael J. Ryan. “The role of sexual selection in maintaining a colour polymorphism in the pygmy swordtail, Xiphophoruspygmaeus.” Animal Behaviour65, no. 4 (2003): 735-743.
  4. Morris, Molly R., and Michael J. Ryan. “Breeding cycles in natural populations of Xiphophorusnigrensis, X. multilineatus, and X. pygmaeus.” Copeia1992, no. 4 (1992): 1074-1077.
  5. MORRIS, MOLLY R., WILLIAM E. WAGNER JR, and MICHAEL J. RYAN. “A negative correlation between trait and mate preference inXiphophoruspygmaeus.” Animal Behaviour52, no. 6 (1996): 1193-1203.

2 thoughts on “Xiphophorus Pygmaeus – Detailed Guide: Care, Diet, and Breeding

  1. Hi Michael,
    Im a bit of a Xiphophorus nerd, so this might be a slightly more complicated question.
    I understand that many species of xiphophorus available in the pet trade (various types of platies,swordtails etc…) are rather outbred with other species of the same genus to produce some of the stunning colors we see today, and thus its incorrect to call a standard platy “X.maculatus” as it is actually a mix of a few different speices of fish. In the pictures provided it appears that that
    Xiphophorus Pygmaeus has not been heavily line bred for colors , so thus are the Pygmaeus available in the hobby true X.Pygmaeus? Or have they been crossbred like many other species of the Xiphophorus genus?
    On a similar topic, when it comes to practicality for Hobbyists, are there any major differences between Pymaeus and standard platies?
    Thank you for putting out such educational articles!

    1. Hi Cory,
      First of all, you are absolutely correct. Many of the vibrant colors seen in various species like platies and swordtails are often the result of selective breeding and hybridization, making it challenging to classify them strictly by their species names.
      When it comes to Xiphophorus pygmaeus, there’s generally less emphasis on intensive color line-breeding compared to some of the other Xiphophorus species. Thus, pygmy swordtails are usually considered to be closer to their wild counterparts in terms of appearance and genetic makeup.
      Nonetheless, I can’t speak for the entire market and all sellers. I can only make assumptions based on general premises. In order to be absolutely precise, molecular research needs to be conducted, which would accurately determine how much the genetic code of the examined specimen differs from the standard.

      Best regards,
      Michael

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