Swordtail Care Guide

September 10, 2025

The Swordtail is one of the classic livebearers of the freshwater hobby — a 4–5 inch active, peaceful, hardy freshwater fish named for the dramatic sword-like extension on the male's tail. At Tropical Treasures Wyo in Cheyenne, Wyoming, Swordtails are one of our most-requested peaceful community fish: bigger and bolder than guppies, just as colorful with bright colors, and even easier to keep long-term thanks to a 3–5 year swordtail fish lifespan.

This swordtail fish care guide covers everything you need to keep Swordtails thriving long-term — tank setup, diet, swordtail fish tank mates, sexing, and swordtail breeding — based on how we actually keep and ship them.

Ready to add some to your freshwater tank? Browse our Swordtail collection — including Pineapple, Tricolor, Lyretail, Tiger, Pink Comet, Santa Claus, and more — every fish quarantined before shipping.

Quick Facts

Scientific name: Xiphophorus hellerii
Common names: Swordtail, Green Swordtail, Sword
Origin: Central America (Mexico, Belize, Honduras)
Average swordtail fish size: Males 4 inches plus 1–2 inch sword extension; females 4–5 inches in length
Swordtail fish lifespan: 3–5 years with good swordtail fish care
Temperament: Peaceful and active; males may chase rivals
Care level: Beginner-friendly
Minimum tank size: 20 gallons; 29+ gallons for groups

Are Swordtails Easy to Care For?

No — they're one of the easiest livebearers and community fish in the hobby and a great step up from guppies for keepers wanting a slightly larger, more substantial display fish. They tolerate a wide range of water parameters including ph range and water hardness, eat anything from flakes to live foods, and breed readily without intervention.

The two areas where new keepers go wrong are tank size (10-gallon tanks are too small for a 4-inch active swimmer) and male-to-female ratio (multiple males in a small tank means constant chasing). Get those right and Swordtails are nearly bulletproof.

Swordtail Fish Tank Size & Setup

Minimum tank size

Trio (1M:2F): 20 gallons
Small group (5–7 fish): 29 gallons
Community tank with Swordtails as feature fish: 29–55 gallons

Footprint matters. Swordtails are active horizontal swimmers and need length, not height — a 20 long freshwater tank is a far better swordtail fish tank than a 20 high.

Substrate

Anything works — sand, gravel, or planted-tank substrate. Swordtails don't sift the substrate. Darker substrate makes their bright colors pop.

Aquatic Plants

Live aquatic plants. Java fern, Anubias, hornwort, Vallisneria, and floating plants like Amazon frogbit are excellent. Floating plants give fry shelter from being eaten, supporting successful swordtail breeding.
Open swimming space. Leave the front and middle of the tank open — Swordtails cruise the full length constantly.
Tight-fitting lid. Swordtails are jumpers, especially when startled or harassed. Cover any gaps in your hood.

Filtration & flow

A standard hang-on-back (HOB) or sponge filter rated for your tank size works well. Swordtails enjoy moderate flow — they're stronger swimmers than guppies and don't mind some current. For more help choosing, read our aquarium filtration guide.

Heating

Yes, Swordtails need a heater. A 50–100 watt heater handles a 20–29 gallon tank. Stable warmth in the mid to upper 70s keeps colors vivid and prevents disease outbreaks.

Water Parameters For Swordtail Fish

Parameter	Ideal Range	Notes
Temperature	72–82°F (22–28°C)	76–78°F is the sweet spot
pH range	7.0–8.0	Slightly alkaline preferred
Water hardness (GH)	10–20 dGH	Hard, mineral-rich water preferred
Carbonate hardness (KH)	5–15 dKH	Higher carbonate hardness for stable pH
Ammonia	0 ppm	Non-negotiable for fish health
Nitrite	0 ppm	Non-negotiable
Nitrate	Under 30 ppm	Tolerant, but lower is better

Stability matters more than perfect numbers. Use a quality dechlorinator like Seachem Prime on every water change. We offer free water testing at our Cheyenne store — bring in a water sample for testing.

Diet & Feeding Swordtail Fish

Swordtails are omnivores with a slight herbivorous lean — they graze algae and biofilm in the wild. Variety is the secret to vivid color in your Swordtail fish.

Staple: high-quality flakes or micro-pellets (Hikari Tropical Flakes, Northfin Community, Xtreme Nano)
Vegetable matter 2–3× per week: spirulina flakes, blanched zucchini, spinach, or peas — important for digestion
Frozen / live foods: brine shrimp, daphnia, frozen bloodworms 1–2× per week
Algae wafers: Swordtails happily graze on sinking wafers shared with bottom feeders

Feed small amounts 2× per day. Overfeeding causes constipation and bloat in livebearers — feed only what they finish in 30 seconds. For more, see our how often to feed your fish guide.

Swordtail Fish Tank Mates

Swordtails are peaceful and pair beautifully with most community tank mates that share their hard, slightly alkaline water preferences.

Great tank mates

Other livebearers — guppies, platies, mollies
Larger tetras — black skirt, Buenos Aires, Congo (avoid fin-nippers)
Rasboras — harlequin, lambchop
Corydoras catfish
Bristlenose plecos
Otocinclus catfish
Peaceful gouramis (honey, pearl)
Rainbowfish in 40+ gallons

Avoid

Fin nippers — tiger barbs, serpae tetras (will shred Swordtail tails, especially Lyretails)
Aggressive cichlids — Convicts, Jack Dempseys, Oscars
Bettas in small tanks (males may attack the trailing sword)
Goldfish — wrong temperature and water parameters
Multiple male Swordtails in tanks under 29 gallons — they'll chase each other constantly

Risky but possible

Neocaridina shrimp. Adult Swordtails usually leave adult shrimp alone but will eat shrimplets. Provide dense moss and plant cover if you want shrimp to colonize alongside them. See our Neocaridina shrimp care guide.

Male vs. Female: How to Sex Swordtail Fish

Sexing adult Swordtails is unmistakable:

Males develop the famous elongated "sword" extension on the lower edge of the tail fin (1–2 inches long), are slimmer in body, and have a thin rod-shaped gonopodium instead of a fan-shaped anal fin.
Females have no sword, are larger and rounder, and have a triangular anal fin. Pregnant females show a dark gravid spot near the anal fin.

Note: Lyretail Swordtail females also have elongated tail extensions, but they're symmetrical (top and bottom) rather than the male's single bottom-edge sword. If you buy a "trio" or "harem" from us at Tropical Treasures Wyo, we hand-select male/female ratios in-store.

Swordtail Breeding Guide

Swordtails are livebearers and breed readily without any intervention.

Setup: A 20+ gallon tank with at least 1 male per 2–3 females reduces harassment. Multiple males in a single tank usually lead to constant chasing.
Mating: Females store sperm and produce multiple broods from a single mating.
Gestation: ~28 days. The gravid spot darkens and the female's belly squares off before delivery.
Birth: Females give live birth to 20–80 fry. Newborns are 1/4 to 1/3 inch long and can eat crushed flake immediately.
Saving fry: Adults eat fry. Use heavy plant cover (Java moss, hornwort, floating plants), a breeder net/box, or a separate fry-grow-out tank to raise them.
Fry food: Crushed flake, baby brine shrimp, microworms, and powdered fry food multiple times a day.

One note unique to Swordtails: under stress or in male-deficient tanks, dominant females sometimes develop male features (a sword) and become functionally male. It's a documented quirk of the species and harmless.

Common Problems & Diseases in Swordtail Fish

Ich (white spot): common after shipping or temperature drops. Treat with heat (82–86°F) and a proper medication. See our Common Fish Diseases guide.
Fin rot: from poor water or fin nipping. Improve water parameters and treat with broad-spectrum antibiotic if severe.
Constipation / bloat: swollen belly with normal scales. Cause: overfeeding or all-flake diet. Fast 2–3 days, then add veggies and live foods (protein-rich food).
Camallanus worms: red worms protruding from the anus. Treat with Fritz Expel-P or levamisole.
Jumping: Swordtails are notorious jumpers — always cover the tank.
Male aggression: too many males in a small tank causes chasing and stress. Keep 1 male per 2–3 females or go all-male / all-female.

Tips for Long-Term Swordtail Success

Cover your tank. Swordtails jump — even a 1-inch gap in your hood is a risk.
Keep a 1M:2-3F ratio. Multiple males in a small tank means constant chasing.
Hard, alkaline water. Swordtails struggle in soft acidic freshwater tanks.
Buy from a quarantining source. Every Swordtail we sell at Tropical Treasures Wyo is quarantined in-house.
Feed varied, small meals. Two small feedings beat one big one and prevent constipation and bloat.
Plan for fry. A male/female tank produces fry constantly — decide whether you want a colony, all-male, or all-female setup.

Frequently Asked Questions

How many Swordtails should I keep together in a tank?

At least 3–5; keep 1 male per 2–3 females to prevent male chasing and aggression. A tank size of at least 20 gallons for a trio is recommended, with 29+ gallons better for groups.

Can I keep a Swordtail in a 10 gallon tank?

No, a 10-gallon tank is too small for even one adult Swordtail, as they are active swimmers reaching up to 5 inches in length. A minimum of 20 gallons is recommended for a single trio (1 male, 2 females).

Can Swordtails live with guppies and mollies?

Yes — they make excellent livebearer community tank mates and share the same water parameters, including hard, slightly alkaline water and peaceful temperament.

Are Swordtails easy to care for?

Yes, Swordtails are beginner-friendly livebearers that tolerate a wide range of water parameters, eat a varied diet including live foods, and breed readily without intervention.

Shop Swordtails at Tropical Treasures Wyo

Visit us in Cheyenne at 190 S College Dr, or order online — we ship healthy, quarantined Swordtails and aquarium supplies nationwide to all 48 states with our 7-day live arrival guarantee.

Shop All Swordtails →
Shop Pineapple Swordtail →
Shop Tricolor Swordtail →

Shop Everything You Need at Tropical Treasures Wyo

Visit us in person at 190 S College Drive, Suite D, Cheyenne, WY 82007 or call 307-369-1118. We offer free water testing for Cheyenne locals, expert advice for every tank size, and nationwide shipping to all 48 states with a 7-day live arrival guarantee.

Back to blog

Your cart

Estimated total