Swordtail
Xiphophorus hellerii
Active livebearer with a bladed tailBeginner
- Lifespan
- 3-5 years
- Size
- 10-14cm / 4-5.5in
- Social needs
- Social; keep in groups
- Time
- 15 min daily; weekly water change
- Cost
- Medium
- Diet
- Omnivore (flake, pellet, veg, live foods)
Overview
What is this animal?
- Swordtails are lively livebearers from Central America, named for the long blade extending from the lower tail of mature males.
- Closely related to platies, they are larger, more active, and need more swimming room than their compact cousins.
- Hardy and adaptable, they come in red, green, pineapple, and tuxedo varieties.
- They are strong swimmers and accomplished jumpers, so they suit keepers who provide length, a secure lid, and stable, slightly hard water.
Temperament
- Swordtails are active and largely peaceful, but mature males can be territorial toward each other, sparring over space and females.
- Keeping a single male, or several with plenty of room and a female-biased group, reduces conflict and stress.
- They are confident, outgoing community fish that occupy open water and rarely hide.
- As ready breeders, mixed groups produce frequent fry, which adults will eat unless dense planting offers the young somewhere to shelter.
A good fit for
- Larger community aquariums with swimming space
- Beginners wanting an active, hardy fish
- Hard-water planted setups
- Keepers who can provide a secure lid
Common mistakes to avoid
- Undersized tanks restricting active swimmers
- Multiple males fighting in tight quarters
- Open tanks letting these jumpers escape
- Low-fibre diets causing constipation
Enclosure
Minimum 95 litres (25 US gallons) — for a group of 3
Cannot be kept alone. The minimum is 3, and the space above is for that group.
- Their size and energy call for a tank of at least 95 litres (25 gallons) with good length, kept at 22-28C (72-82F) in hard, alkaline water and filtered to keep nitrate low.
- Open swimming space matters more than height for these powerful swimmers.
- A tight-fitting lid is essential, as swordtails are notorious jumpers.
- Provide planting at the sides and back for cover and fry refuge while leaving the central water column clear for their constant activity.
Supplies
Setup
- Tank and stand
- Filter
- Heater and thermometer
- Substrate, plants and decor
- Liquid test kit
- Dechlorinator and starter supplies
Ongoing
- Quality tropical flake or micro-pellet
- Spirulina or vegetable flake
- Frozen brine shrimp and daphnia
- Frozen or freeze-dried bloodworm
- Veg clip for courgette and spinach
- Baby brine shrimp hatchery or frozen equivalent for fry
- Fine net for removing leftovers
Safe substrate: Inert aquarium gravel · Fine, smooth sand · Aquasoil for planted tanks
Care routine
Daily
- Check temperature and equipment
- Feed
- Head-count and look everyone over
Weekly
- Top up evaporationevery 3 days
- Clean glass and clear algae
- Test the water
- Water change and gravel vacuum
Monthly
- Trim and thin the plantsevery 2 weeks
- Check supplies and reagent dates
- Review the fry plan
- Rinse the filter media
Less often
- Replace chemical filter media (Carbon/Purigen)every 2 months
Vet: Quarterly stocking and health review — every 3 months
Top resources for more info
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Diet
- Swordtails are omnivores that do best on a varied, vegetable-inclusive diet.
- Use a quality flake or pellet base, add spirulina, algae, and blanched greens, and offer frozen or live foods such as bloodworms, daphnia, and brine shrimp several times a week.
- Feed modest amounts once or twice daily, only what is consumed quickly.
- Like other livebearers they tend to overeat and can become constipated on a low-fibre diet, so keep vegetable matter a regular part of the menu.
Health
- Swordtails are robust given clean, hard, stable water, but suffer ich, fin rot, and constipation under neglect or poor diet.
- Steady warmth, strong filtration, and weekly water changes prevent most disease in this hardy species.
- Mass-bred stock can be genetically weaker, so source carefully and quarantine new fish.
- Watch for clamped fins, white spots, or a swollen belly with stringy faeces, signs of parasite or dietary trouble that respond to corrected care.
Is your enclosure big enough?
Is this urgent?
In a fish tank the patient is usually the water. Test before you treat — dosing a healthy tank for a disease it does not have makes things worse.
Go now
Today
Soon
Never add a new fish to a tank that is not fully cycled, and never treat blind. A test kit is cheaper than the fish.
This is general guidance for a healthy adult, not a diagnosis. An exotics vet who knows your animal always overrides it — and the time to find one is before you need one.
What it really costs
Setup, monthly, first year and across a whole life, itemised and with the electricity worked out from the actual wattage. Published figures for the same animal disagree by a factor of four, so the calculator shows ranges rather than picking one.
Bedding and substrate
Substrate in an aquarium is a filter as much as a floor. Most of the biology lives in and on it.
Safe
With a caveat
Never
This is our general list for freshwater fish. We have not built one specific to Livebearers yet.
My kit says 0.25 ppm. Is that dangerous?
A liquid kit measures total ammonia, but only the un-ionised fraction is really toxic, and that fraction is governed by pH and temperature — each whole pH unit multiplies it roughly tenfold. So the same reading can be nearly harmless in one tank and lethal in another; this works out which one you are in.
Compare with other animals
The same axes for every animal, side by side — the way the guides are written makes that a fair comparison rather than two articles.
Livebearers, side by side
Same axes, same care guides — the honest way to choose between types.
See all Livebearers side by side →
