Red Swordtail
Xiphophorus hellerii
Red Swordtail (Xiphophorus hellerii) is a freshwater species with an adult-size reference of about 12 cm. It needs at least 100 litres and 4 individuals, with its social and territorial profile taken into account.
Water Temperature
22 - 28 °C
pH Value
7 - 8.5
Water type
Freshwater
Tank level
Middle
Adult size
12 cm
Minimum tank volume
>= 100 L
Minimum group
>= 4
GH
10 - 30 dGH
KH
5 - 15 dKH
TDS
200 - 600 ppm
Conductivity
313 - 938 uS/cm
Species description
Geographical Origin and Habitat: A freshwater species; the enclosure should provide stability, oxygenation, space and shelter consistent with its behaviour without turning one habitat description into a mandatory recipe.
Taxonomy and Morphology: The accepted scientific name is Xiphophorus hellerii; the verified classification records genus Xiphophorus, family Poeciliidae, subfamily Poeciliinae, order Cyprinodontiformes. Historical names remain searchable as synonyms rather than separate species.
Social Behavior: Red Swordtail should be kept with more females than males so courtship pressure is distributed. The minimum reference is 4 individuals; sex, maturity and available space can require a more conservative composition. Observe access to food, resting behaviour, chasing and use of shelter. Isolation, persistent competition or aggression means the number, composition or environment needs to be corrected.
Coloration and Sexual Dimorphism: Colour and shape can vary with age, sex, physiological state and environmental conditions. Identification and sexing require recognized species-level characters; one appearance or photograph is not enough.
Care, breeding and tankmates
Aquarium Setup: Red Swordtail needs an aquarium of at least 100 litres, sized for adult body size and a minimum group of 4 individuals. Filtration, shelter and swimming room must match the species and the actual number kept. Volume alone does not make an enclosure suitable: tank shape and length, usable area, oxygenation and the ability to separate territories must reflect adult behaviour.
Diet and Feeding: The recorded diet is omnivorous. Offer appropriately sized foods varied within that category, and adjust quantity and frequency from actual intake, body condition and leftovers. One food or a fixed schedule is not suitable for every age and situation.
Water Quality: Maintain stable, well-oxygenated water appropriate to a freshwater species; the card's reference values are 22–28 °C, pH 7–8.5. Verify conditions with reliable tests and size maintenance and filtration to the actual load. Ranges are not automatic thresholds for treatment or rapid chemical correction.
Compatibility and Cohabitation: The cohabitation profile is suitable for a compatible community, with a generally active temperament. Keep at least 4 individuals; tankmates, stocking density and decor must allow escape, rest and feeding without excessive competition. Watch interactions especially during feeding, maturity and breeding. Persistent chasing, injury or exclusion from food requires a change in stocking or layout, or separation of the animals.
Aquarium Breeding: The recorded reproductive profile is “viviparity”. Breeding should be attempted only with healthy adults, separation capacity and a plan for eggs or young. Do not treat unverified triggers, sex ratios or hatch times as universal for this species.
Risks and Diseases: Use a secure cover and close escape gaps. Prevent problems through quarantine of new arrivals, stable water, appropriate feeding and daily observation. Similar signs can have different causes, so check parameters, history and diagnosis before medication. Follow the product label and qualified aquatic-veterinary advice; there is no universal reduced dose for a species or family.
Geographic origin and distribution
A freshwater species; the enclosure should provide stability, oxygenation, space and shelter consistent with its behaviour without turning one habitat description into a mandatory recipe.
Origin
Central America and Caribbean
Fish profile
- Temperament
- Active
- Red Swordtail has a generally active temperament. Insufficient space, an unsuitable social ratio or incompatible tankmates can substantially change observed behaviour.
- Diet
- Omnivore
- Swordtails are indiscriminate omnivores that eagerly consume almost anything offered to them. A high-quality flake or pellet food formulated for tropical fish serves as a fantastic daily staple. They highly benefit from vegetable matter, so spirulina flakes or blanched zucchini should be rotated into their diet frequently. Occasional treats of frozen bloodworms or brine shrimp will enhance their coloration and breeding vigor.
- Life expectancy
- 3-5 years
- Adult size
- 12 cm
- Sex ratio
- Specific M:F ratio
- Red Swordtail should be kept with more females than males so courtship pressure is distributed. The reference minimum is 4 individuals and must not be read as permission to overcrowd the aquarium.
- Feeding frequency
- Twice daily
- They have hearty appetites and do best when fed small portions once or twice a day. They will actively graze on naturally occurring algae in the tank between meals, which aids their digestion. It is important to only feed what they can consume in two minutes to prevent water fouling. Overfeeding is rarely an issue for the fish itself, but it can quickly degrade water quality.
- Bioload
- Medium
- Swordtails generally have a moderate bioload that is easily managed in a properly filtered aquarium. Because they are prolific breeders, the sudden addition of dozens of fry can occasionally cause temporary spikes in ammonia if not monitored. Standard hang-on-back or sponge filters provide more than adequate biological processing for adult groups. Regular maintenance and routine water changes will keep their environment perfectly stable.
- Flow
- Moderate
- Originating from flowing streams and rivers in Central America, they appreciate a moderate, steady water current. A decent flow mimics their natural habitat and encourages their active, vigorous swimming behavior. While they enjoy current, it shouldn't be so strong that it exhausts them or creates a whirlpool effect. A standard filter return usually provides the perfect amount of water movement.
- Jump risk
- Yes
- Swordtails are incredibly athletic and are notorious for jumping out of the aquarium. They can easily propel themselves over the edge if startled, during mating chases, or if water parameters drop. A tight-fitting lid covering the entire surface, including filter cutouts, is absolutely mandatory for their safety. Many aquarists have lost prized males simply because they left the lid open overnight.
- Reproduction
- Viviparous
- They are prolific livebearers, meaning the females give birth to fully formed, free-swimming fry rather than laying eggs. A single female can drop anywhere from 20 to 80 fry every month without any special intervention. Unless the tank is heavily planted with dense cover like java moss, the adults will quickly cannibalize their own young. For high survival rates, pregnant females should be moved to a dedicated breeding box.
- Compatibility & tankmates
- Community
- The cohabitation profile is suitable for a compatible community, with a generally active temperament. Keep at least 4 individuals; tankmates, stocking density and decor must allow escape, rest and feeding without excessive competition. Watch interactions especially during feeding, maturity and breeding. Persistent chasing, injury or exclusion from food requires a change in stocking or layout, or separation of the animals.
- Tank level
- Middle
- They are highly active fish that utilize every level of the aquarium, from the top surface to the bottom gravel. However, they predominantly cruise the mid-to-upper levels looking for food and socializing. They appreciate tall background plants that break up lines of sight and offer resting spots. Providing ample open horizontal swimming space is crucial for these energetic swimmers.
Scientific Parameters & Models
FishBase
Window to the official scientific data of the species
FishBase v25.04Data synced on: 06/15/2026
- Trophic level
- 3.2 ± 0.43 se
- Resilience
- High (less than 15 months)
- Phylogenetic uniqueness (PD50)
- 0.5
- Bayesian Length-Weight
- a = 0.01, b = 3.06
- VulnerabilityLow vulnerability (10 / 100)
Image gallery
Licensed images linked to the species or, when marked, to the closest representative taxon.
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