Livebearers · Xiphophorus hellerii

Swordtail care guide

Also called: Green swordtail, Red swordtail, Swordtail fish, Red wag swordtail, Lyretail swordtail

The swordtail is a lively, peaceful livebearer named for the long sword on the male's tail. It grows bigger than a platy, often 4–5 in (10–12 cm), so it needs a long tank, hard water, a tight lid and only one male in smaller setups.

Swordtails need a tank of at least 29 gallons (110 L), a group of 4 or more, and water at 22–26°C (72–79°F) with a pH of 7–8. They grow to about 12 cm (4.7 in) and are peaceful.

Plan a tank with swordtailsSee all tank mates

Swordtail quick facts

Scientific nameXiphophorus hellerii
FamilyPoeciliidae
OriginAtlantic slope of southeastern Mexico, Guatemala, Belize and northwestern Honduras (aquarium swordtails are captive-bred, often with platy genes)
Adult size12 cm (4.7 in)
Minimum tank29 gallons (110 L), at least 90 cm (35 in) long
Temperature22–26°C (72–79°F)
pH7–8
Hardness (GH)10–20 dGH
Group size4 or more (1 male, the rest females)
TemperamentPeaceful; males fight each other
Swims atMiddle
DietOmnivore
Care levelEasy
Lifespan3–5 years
Safe with shrimp?No, eats shrimp
Safe with plants?Yes
  • Known jumper: keep a tight-fitting lid.

Tank setup

Swordtails are fast, active swimmers. Give one male and a few females a tank at least 3 ft (90 cm) long, which usually means 30 gallons (110 L) or more. Leave open swimming space along the front, with plants around the sides and back. Keep a tight lid on, because swordtails jump.

How many swordtails in a tank?

The smallest common tank that suits swordtails is a 40 gallon. Here is roughly how many fit in each size when they are the only fish, based on adult size and waste output. Leave room if you want tank mates.

TankSwordtails (alone)
3 gallonToo small
5 gallonToo small
10 gallonToo small
15 gallonToo small
20 gallonToo small
20 gallon longToo small
29 gallonToo small
40 gallon4–10
55 gallon4–14
75 gallon4–19
125 gallon4–32

Numbers are bioload limits only. Males fight, so keep a group of 4 or more with more females than males.

What you need for swordtails

Sized for a 29 gallon tank, the smallest common size that suits a group of 4 swordtails. For a different tank or a mix of fish, use the stocking calculator for a list sized to your plan.

Tank and equipment

Food and extras for swordtails

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Water parameters

Aim for 22–26 °C (72–79 °F), pH 7.0–8.0 and moderately hard water of about 10–20 dGH. They handle a fairly wide range but do poorly in soft, acidic water. Wild swordtails live in flowing streams, so keep the water clean and well oxygenated with weekly changes of about 25%.

Best tank mates for swordtails

These popular species share swordtails' water needs and temperament. See the full list of 96 good matches.

Avoid keeping swordtails with

  • Cherry shrimp: Swordtail eats small shrimp like cherry shrimp.
  • Chinese algae eater: Chinese algae eater is aggressive and will bully or injure peaceful swordtails.
  • Convict cichlid: Convict cichlid is aggressive and will bully or injure peaceful swordtails.
  • Discus: They need different temperatures: Swordtail 22–26°C (72–79°F), discus 28–30°C (82–86°F).
  • Electric yellow cichlid: Electric yellow cichlid is a Lake Malawi cichlid. It needs a Lake Malawi tank: hard, alkaline water (pH 7.5–8.5), plenty of rockwork and other cichlids from the same lake. Swordtails don't belong in that setup.
  • German blue ram: They need different temperatures: Swordtail 22–26°C (72–79°F), german blue ram 27–30°C (81–86°F).

Feeding

An easy omnivore. Feed a quality flake or small pellet as the staple, plus vegetable flake or algae wafers and frozen foods such as brine shrimp, daphnia and bloodworm. Feed once or twice a day, only what they eat in a couple of minutes.

Behavior

Swordtails are generally peaceful toward other fish but very busy. Rival males squabble, so a modest tank should hold a single male. In a big tank, three or more males spread out the tension, as long as females outnumber them. Some swordtails nip long fins, so avoid bettas and fancy guppies. Adults also eat dwarf shrimp.

Breeding

Females give birth roughly every 4–6 weeks, usually to 20–100 fry. Adults eat their young readily, so use dense plants or a separate nursery tank if you want to raise them. Swordtails interbreed with platies, and most store swordtails already carry some platy genes.

Tips from experienced keepers

  • Keep one male per tank unless the tank is large. Two males in a small tank often ends with one bullied constantly.
  • Keep three or four females per male to spread out the male's attention.
  • Fit a tight lid. Startled swordtails can jump out of open tanks.
  • Choose a long tank over a tall one. Swimming length matters more than height for this fish.
  • Skip dwarf shrimp. Larger Amano shrimp in a well-planted tank have a better chance.

Frequently asked questions

How many swordtails should be kept together?

Keep at least four: one male with three females is a good start. In large tanks several males can work, as long as females outnumber them and there is plenty of cover.

Can swordtails live with platies?

Yes. They need the same water and are equally peaceful. They are close relatives and can interbreed, so expect mixed fry if you keep both sexes.

Can swordtails live with shrimp?

Not with dwarf shrimp like cherry shrimp. Adult swordtails are big enough to eat them, especially right after a molt. Larger Amano shrimp in a heavily planted tank are a safer choice.

Sources

We checked these references when writing this page. Values are for healthy long-term keeping, not survival limits. Last reviewed 2026-10-13. See our editorial policy.