TankBud

Variety of Green swordtail

Red swordtail

Xiphophorus hellerii

One of 6 varieties of Xiphophorus hellerii · See all varieties →

FreshwaterFish

Red swordtail (Xiphophorus hellerii)
The Wet Spot Tropical Fish · Used with permission

Varieties · Xiphophorus hellerii

See all 6 →

Care at a glance

Temperature
68–82°F
20–28°C
pH
7.0–8.0
Adult size
5.9 in
15 cm
Minimum tank
24 gal
90 L
Temperament
Peaceful
Social behavior
Social
Swim level
Middle
Difficulty
Beginner
Breeding
Easy
Rarity
Very common
Family
Poeciliidae

Overview

The default shop swordtail, sold plain red or as a wagtail with black fins. Color quality varies between farms: some fish are an even deep red, others patchy orange with dark flecking. Pick individuals if the shop will let you, since a tank of red swordtails is rarely uniform. Males show a sword and a narrow rod-shaped anal fin, so sexing adults is easy.

In the wild

Red is a farm color, not a wild one. The USGS nonindigenous species database lists the red swordtail as a hybrid of Xiphophorus hellerii and the platy Xiphophorus maculatus, and notes that the two are often crossbred in captivity. Hobby accounts trace the red back to red platy stock, and farms have worked that cross for roughly a century. No fish this color swims in the wild streams the species comes from.

Good to know

Red sits in erythrophores, the red pigment cells, and domestic red lines stack far more of them than a wild green fish carries. Because the color arrived by hybridizing with platies, shop red swordtails are hybrids rather than pure Xiphophorus hellerii. The color breeds mostly true, though off-colored culls turn up in most spawns. Wagtail black on the fins came out of those same platy crosses, and hobby genetics accounts put two of the three alleles behind it in Xiphophorus maculatus.

Did you know

A red male's sword is shorter than a wild green male's. That is a side effect of the platy blood in the line. Platies have no sword at all, and the crossing that brought in the red also trimmed it.

Weekly picks

Tank mates

Red swordtail is a peaceful, social species that keeps to the middle. These picks share a community profile with it, are safe together in both directions, and overlap on water type, temperature and pH.

Check the full mix in the stocking calculator

Common questions

Is a Red swordtail a different species from the Green swordtail?

No. A Red swordtail is a variety of the Green swordtail, Xiphophorus hellerii, and it wants the same tank, water and food as the species.

What size tank does a Red swordtail need?

A Red swordtail needs at least 24 gal (90 L). It spends most of its time in the middle.

How big does a Red swordtail get?

An adult Red swordtail reaches about 5.9 in (15 cm).

Related species