Xiphophorus maculatus, commonly known as the Southern platyfish, thanks to its endurance and bright coloring, is among the most popular aquarium fish.
These fish will be an excellent choice even for small tanks. Southern platyfish are small, omnivores, hardy, very easy to care for, and readily acclimatizing to new environments. Therefore, they are often recommended for beginners as their first fish.
In this detailed guide, I have gathered all information about Xiphophorus maculates based on existing studies, research, experiments, and the experience of aquarists. You will know more about this remarkable fish including their behavior, feeding preferences, ideal tank requirements, and how to take good care of them.
| I think we should start by saying that finding a pure strain of Xiphophorus maculatus is almost impossible nowadays.
This species is highly susceptible to hybridization. So, at the moment, what we have under this name is, in fact, in 99% of cases, the result of hybridization and selection with other Xiphophorus species (such as Xiphophorus variatus, Xiphophorus hellerii (Swordtails), etc.). |
Quick Notes about Southern Platyfish
| Common Name | Southern platyfish |
| Other names | Plalypocdus maculatus, the Mexican Platyfish, Moon fish, and Platy |
| Scientific Name | Xiphophorus maculatus |
| Water type | Freshwater |
| Tank size (minimum) | 15 gallons (~60 liters) |
| Keeping | Easy |
| Breeding | Easy |
| Size | up to 1 – 3 inches (3 – 7 cm) |
| Optimal Temperature | 68 – 75°F (20 – 24°С) |
| Optimal PH | 7.0 – 8.0 |
| Optimal GH | 5 – 20 |
| Dwellers | Top to mid-dwelling |
| Nitrate | Less than 60 |
| Diet | Omnivore |
| Temperament | Peaceful |
| Life span | up to 3 years |
| Color Form | Over 130 color variations created through selection. Wild populations are generally a pale olive-grey with or without melanic/speckled patches. |
Etymology of Southern Platyfish
The genus name “Xiphophorus” is derived from two Greek words “Xiphos”, which means “Sword”, and “Phoros”, which means “Bearer”. This name refers to the sword-like extension of the lower part of the tail fin, a distinctive feature of fish in the Xiphophorus genus.
The species name “Maculatus” comes from the Latin word “Maculatus,” which means “Spotted or marked”. It describes the spotted or marked appearance of this species, particularly in reference to its coloring.
Taxonomy of Southern Platyfish
The southern platyfish has been studied for over 130 years. They were first named Platypoecilus maculatus. Basically, that genus name referred to both their flattened body and the numerous colors they exhibit.
Nowadays, Platyfish are subsequently placed in the genus Xiphophorus with swordtails.
- Kingdom: Animalia (Animals)
- Phylum: Chordata (Chordates)
- Class: Actinopterygii (Ray-finned fishes)
- Order: Cyprinodontiformes (Cyprinodontiformes)
- Family: Poeciliidae (Livebearers)
- Genus: Xiphophorus
- Species: Xiphophorus maculatus
Although Xiphophorus maculatus does not have a long tail, it still possesses other characteristics of the Xiphophorus genus. These include aspects of its anatomy, reproductive behavior, and genetic relationships.
Distribution of Southern Platyfish
Xiphophorus maculatus is native to Mexico (from southern Tamaulipas to northern Veracruz), Belize, and Guatemala (Peten district, Aha Verapaz).
However, this species has proven highly invasive because of wide environmental tolerances. As a result of human-mediated release, it is now present in at least 18 countries where it wasn’t originally found.
Introduced: Madagascar, Mauritius, Nigeria, Réunion, Kerala, Indonesia, Japan, Saudi Arabia, Singapore, Sri Lanka, Austria, Germany, Bahamas, Canada, Honduras, Jamaica, Puerto Rico, California, Colorado, Florida, Hawaii, Louisiana, Montana, Nevada, Texas, Palau, Paraiba, Colombia, and Peru.
| At least one country reports adverse ecological impact after introduction.
In Hawaii, Xiphophorus maculatus and other poeciliids are considered responsible for the decline of indigenous aquatic invertebrates. |
Habitat of Southern Platyfish
In their natural habitat, Xiphopkorus maculatus often occur in tranquil stream banks, stagnant pools, ditches, and sun-drenched flooded areas.
Typically, they inhabit areas with muddy substrate and dense vegetation.
Description of Southern Platyfish
Xiphopkorus maculatus is a relatively small freshwater species. The average size of the adult males is only about 1.2 – 1.5 inches (or 3 – 4 cm) long. Females are significantly larger and can grow up to 2 – 2.5 inches (5 – 6 cm) in length. In some rare cases, they can exceed 3 inches (7 cm) long.
- Shape: They have small, oval-shaped, laterally-compressed bodies, with a maximum body depth of approximately half of the standard length.
- Fins: This species has 7 to 11 (usually 8 – 10) dorsal soft rays. Males possess a modified anal fin called a gonopodium. The gonopodium does not extend to the caudal fin base and the third ray has a strong hook.
- Lateral scales: The number of scales along the fish’s side typically ranges from 22 to 25 (with 23 to 24 being the most common count).
- Vertebrae: Xiphophorus maculatus usually has 26 to 28 vertebrae.
- Color: The coloration and color patterns of Platy fish can vary widely due to selective breeding. Common colors include red, black, white, blue, orange, yellow, and their various combinations and patterns. In platyfish, both males and females express conspicuous color patterns.
Note: There are over 130 color variations created through selection whereas fish from wild populations are less colorful than ornamental varieties and are generally a pale olive-grey with or without melanic/speckled patches. - Eyes: They have relatively large eyes compared to body size. They are adapted for both daytime and low-light conditions.
- Mouth: The mouth is small, upturned, and suited for surface feeding. They have two rows of jaw teeth.
Difference between Xiphophorus maculatus and XiphophorusVariatus
These two species are so similar to each other that in most cases, it can be quite difficult to distinguish them for ordinary hobbyists. Furthermore, considering the possibility of hybridization between them, genetic studies may be required for that.
Nevertheless, according to the scientific literature, the distinctive features include:
| Xiphophorus maculatus | Xiphophorus variatus | |
| Anal fin ray | small claw at the tip of the fifth anal fin ray | no claw at the tip of the fifth anal fin ray |
| Lateral scales | 22 – 25 | 20 – 24 |
| Dorsal rays | 8 – 10 | 10 -12 |
| Male size | smaller | slightly larger |
Lifespan of Southern Platyfish
Currently, there is no data available on the maximum lifespan for Xiphophorus maculates in the wild.
In aquariums though, under optimal conditions, they can live up to 2 – 3 years.
Their lifespan will greatly depend on the conditions they are kept in, how well you feed them, and how stressful your aquarium environment is for them. These small fish live most in an aquarium containing low food competition and the absence of various larger or aggressive animals.
Typical Behavior of Southern Platyfish
Temper:
Southern platyfish are quite peaceful fish. They will not bother anybody in the community tank. These fish do not exhibit aggressive behavior to other species of fish.
Although males of this species are not territorial, they will compete for dominance wih each other. Their aggressive encounters usually include chases and lateral displays with a raised dorsal fin, in rare cases, they can even bite.
Interesting fact: When two individuals are reared together the socially dominant individual delays the maturation of the subordinate.
Note: Territoriality has been reported for only one poeciliid -Poeciliopslslucida.
Sociality:
Although Xiphophorus maculates is a social species, they do not stay in close proximity all the time. Thus, it is not schooling but rather a shoaling fish.
In the aquarium, you need at least 6-8 of them to start. Large groups make them happier and less stressful
Ideally, you need to have 1 male per 3-5 females. In their natural habitats, there are also more females than males.
Activity:
Southern platyfish are moderately active fish. Generally, they do not swim like crazy in aquariums but when they do, they are very quick.
They are also good jumpers when stressed or scared.
Placement in Tank:
Generally, they spend most of their time at the top and middle parts of the tank.
Features:
- Social: Yes
- Activity: Moderate
- Placement: Top and middle dwellers
- Peaceful: Yes
- Nippers: No (rarely)
- Jumpers: Yes (rarely)
Diet of Southern Platyfish
This species is omnivorous. In nature, these fish feed on microscopic organisms, including insect larvae in densely vegetated areas.
Southern platyfish are surface-feeders, as the mouth is upwardly directed because of the jaw structure.
They are not finicky at all and can eat basically everything. They will gladly accept frozen and commercial food as well, as far as it is small enough to fit into their mouth for mastication and digestion
Nonetheless, this species still has a strong preference for live food (high-protein) food. Therefore, in the aquarium, we can feed them:
- brine shrimp (artemia salina),
- artemia nauplii,
- cyclops,
- daphnia,
- fruit flies, etc.
Large worms (grindal worms, bloodworms, blackworms, etc.) should be chopped into small pieces and flake food should be crumbled.
How to Feed Southern Platyfish?
- They are diurnal animals; these fish should be fed during the day.
- As surface feeders, their mouths are developed to catch prey above them. They rarely pick anything on the substrate. Ideally, you need some food that will stay in the water column for some time.
- Be prepared to cut in pieces or grind up some flakes.
- Make sure it is mostly a protein-based diet.
- They are prone to overeating if given too much (follow a “5-minute rule”).
Features:
- Diet Type: Omnivore
- Food Preference: Protein-rich
- Feeding Frequency: Daily
How Often to Feed Southern Platyfish?
Ideally, Southern platyfish should be fed at least twice per day (in the morning and the evening).
Are Southern Platyfish Plants Safe?
Yes, Southern platyfish are plant safe. They do not eat live plants.
Even more, planted tanks are highly recommended for them, especially for breeding purposes.
Keeping and Housing Southern Platyfish
Although these fish are hardy and can withstand varied ranges of water parameters, we still need to address their core needs if we want them to thrive and breed.
Important: Make sure that you cycle your tank before bringing these fish home. Once the tank is cycled you need to check the quality of the water using a test kit.
Tank size:
The minimum recommended tank size for this species is 15 gallons (60 liters) for 1 male and 4 – 5 females. This gives them adequate swimming space.
Nonetheless, having a larger tank is always preferable for the stability of water chemistry.
Important: Southern platyfish are jumpers. Therefore, to prevent it from happening, there are a few things you can do:
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Water Parameters:
Temperature: Southern platyfish can survive in a wide range of temperature conditions 59 – 82°F (15 – 28°C). However, at low temperatures, they become slow, lethargic, and barely eat. In the aquarium, they will thrive in warm temperature conditions of 68 – 75°F (20 – 24°С).
Important: It does not mean that the temperature in your tank can fluctuate that much in short periods of time! The range of their tolerance is strongly influenced by acclimation temperature. In other words, fish that are acclimated at lower temperatures can extend their lower temperature tolerance further compared to fish acclimated to higher temperatures.
pH: This species generally prefers slightly alkaline conditions. The ideal pH range should be between 7.0 – 8.0.
Hardness: These fish can live in any water but they will appreciate optimal GH between 5 – 20. It’s worth noting that Southern platyfish prefer hard water. When kept in very soft water, they are more prone to disease.
Salinity: These fish can tolerate moderate amounts of salt in the water. Although their natural habitat usually does not have fluctuations in salinity, they can withstand salt levels up to about 3 parts per thousand (ppt).
Note: Salt can be added periodically to platy aquariums as a preventative treatment against some parasites and infections.
| Important: If you do choose to use salt, make sure to only replace water with salted water during water changes. This is because when water evaporates, it leaves salts behind, so adding more salt to top off evaporated water is unnecessary. |
Lighting:
As for lighting, Southern platyfish prefer subdued lighting.
However, if you decide to keep these fish in planted tanks, lighting should be adapted to the needs of plants.
Related article:
Water Flow:
In the natural ecosystem, these fish inhabit shallow waters where the current is absent or very slow-moving.
Still or very slow water currents are recommended for tanks housing this species.
Substrate:
No special requirements.
Southern platyfish don’t disturb substrate much. Bare bottom tanks are also suitable.
Tip: Although you can choose any substrate for the tank, it is better to have a dark color so that the fish looks more contrasting against its background.
Plants and Decorations:
The natural habitat of Southern platyfish is abundant in vegetation. Plants provide good hiding spots for them. It makes them happy and playful.
This should be replicated in their tank.
You can use floating plants, fake plants, driftwood, leaves, and small rocks to provide additional hiding spots for them.
Water Changes:
You must change 20-25 % of their water every week. However, you may need to remove a different percentage of water depending on your filter and other tank factors.
Keep in mind that any water that you add to the tank should also be at least dechlorinated.
Note: Dechlorinators can be purchased at any pet store, (Seachem Prime – link to check the price on Amazon), to make sure the water is safe for your fish.
Breeding Southern Platyfish
Breeding Xiphophorus maculatus is quite simple and easy. Moreover, it’s not so much a question of how but when.
All you need is to keep them in acceptable water parameters and feed them daily. It will lead to almost continuous reproduction.
These fish are livebearers, they are not egg scatterers.
Maturity:
Depending on the temperature, Xiphophorus maculatus mature between 2.5 – 5 months old when they are about 0.8 inches (21 mm) long.
The growth rate of immature males and females is almost the same. Nonetheless, it declines sharply in males (but not females) at the time of sexual maturity. This leads to significant differences in adult size between them.
Sexing:
Mature males can be easily distinguished from females by the size and the presence of the gonopodium.
- Size. Males are smaller (almost half the size of females).
- Males possess a modified anal fin called a gonopodium that is used to inseminate the female. Females have a normal fan-shaped anal fin.
Mating:
Laboratory observations of gravid females indicate that males of Xiphophorus maculatus may mate with more than one female and females mate with more than one male.
In most cases, the courtship behavior begins almost immediately or as soon as the male is aware of the females in the aquarium. If the female is ready, copulation usually takes place after twenty minutes or less of courtship.
Interesting fact: When a female had mated with more than one male, usually both had fathered some young of a given brood.
Additionally, there is a positive relationship between the number of inseminating males and the number of young. Experiments showed that when females mated with only 1 male they had nearly half as many offspring as those that mated with 3 to 4 males.
According to the study, males increase the intensity of sexual displays both when other males are present as well as when predators are absent.
Fertilization:
Southern platyfish have internal fertilization.
Interesting fact: Females can store spermatozoa and use it for later fertilization. For example, in the laboratory, females had been producing offspring for up to 7 months after having been inseminated.
Brood size:
In Xiphophorus maculatus, the mean brood size ranges from 15 to 25. Large females exhibit a maximum fecundity of approximately 90 offspring.
Females are not receptive all the time. Brood intervals for this species range from 17 to 65 days.
Generally, females produce up to 7 broods during their lifespan. However, under optimal conditions, the results can be higher. It was recorded that in the laboratory, females have had as many as 13 broods in a 14–15 month period.
Interesting facts: Initially, broods tend to be smaller in the number of offspring, than tend to increase in number over time.
Incubation:
Embryonic development may vary from 27 to 37 days, depending on the temperature. At 76°F (24°C) the gestation period is usually about 32 days.
It was also noted that the virgin females usually did not give birth to their first brood until about 40 days after fertilization. Scientists do not have an explanation for that.
Fry:
Parents do not care for fry after birth. Once the fry are born, they should be separated from the parents (and other fish) to avoid predation. Thus is better to have a special rearing tank for that.
Live food is the best choice for fry.
According to the study, the fry should be fed a high-quality diet (such as artemia, rotifers, vinegar eels, microworms, or infusoria) at least 2 times a day and the water should be changed frequently.
Southern Platyfish and Suitable Tankmates
- Fish
These small fish can be kept only with fish that are not big enough to eat or harass them. If you still decide to keep this species in community tanks, keep in mind that all tank mates should have at least a gentle temperament and enjoy the same water parameters, such as:
- Endlers,
- Swordtails,
- Mollies,
- Neons,
- Ghost Glass Catfish,
- Pygmy Cory,
- Boraras,
- Panda Garra,
- Clown Killifish,
- Guppies,
- Harlequin Rasboras,
- Otocinclus,
- Medaka Ricefish, etc.
Dwarf shrimp
Not recommended. Keeping Southern platyfish with dwarf shrimp is very risky.
Their small size should not mislead you into thinking that they cannot do any harm to the shrimp. Yes, they can.
These fish will prey on shrimplets and harass molting shrimp, leading to unfavorable outcomes.
Even heavily planted tanks will not provide sufficient hiding places for baby shrimp. Therefore, if you are serious about maintaining a thriving shrimp population, the safest course of action is to keep the shrimp separate from Southern platyfish.
Freshwater snails:
Southern platyfish can share the same tank with any type of freshwater snail.
Summary of Bad Tank Mates for Southern Platyfish:
- Larger or aggressive fish.
- Dwarf shrimp.
- Most crayfish and freshwater crab species. They may prey on or nip the fins, especially at night.
- Even Dwarf frogs may try to eat small males.
In Conclusion
Xiphophorus maculatus is a species of live-bearing fish that has been popular in the aquarium hobby for many decades because of their hardy nature, fast growth rates, unique pigmentation, and a variety of coloration.
These fish are also pretty active. So, if you are looking for something small and beautiful, then this is the fish for you.
References:
- Orzack, Steven Hecht, Joel J. Sohn, Klaus D. Kallman, Simon A. Levin, and Ross Johnston. “Maintenance of the three sex chromosome polymorphism in the platyfish, Xiphophorus maculatus.” Evolution(1980): 663-672.
- BOROWSKY, R., AND K. D. KALLMAN. 1976. Patterns of mating in natural populations of Xiphophorus (Pisces: Poeciliidae). I: X. maculatus from Belize and Mexico. Evolution 30:693-706.
- Sohn, Joel J. “Socially induced inhibition of genetically determined maturation in the platyfish, Xiphophorus maculatus.” Science195, no. 4274 (1977): 199-201.
- Kallman, Klaus D., Martin P. Schreibman, and Valerie Borkoski. “Genetic control of gonadotrop differentiation in the platyfish, Xiphophorus maculatus (Poeciliidae).” Science181, no. 4100 (1973): 678-680.
- Vallowe, Henry H. “Some physiological aspects of reproduction in Xiphophorus maculatus.” The Biological Bulletin104, no. 2 (1953): 240-249.
- Basolo, Alexandra L. “Genetic linkage and color polymorphism in the southern platyfish (Xiphophorus maculatus): a model system for studies of color pattern evolution.” Zebrafish3, no. 1 (2006): 65-83.
- Rosen D, Bailey DR. The poeciliid fishes (Cyprinodontiformes), their structure, zoogeography, and systematics. Bull Am Mus Nat Hist 1963;126:1–176.
- Allen GR, Midgley SH, Allen M, 2002. Field guide to the freshwater fishes of Australia. Field guide to the freshwater fishes of Australia, xiv + 394 pp.
- Borowsky, Richard L. “Social control of adult size in males of Xiphophorusvariatus.” Nature245, no. 5424 (1973): 332-335.