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Contents
Overview
The swordtail is unmistakable: males have the lower rays of the tail fin extended into a "sword" that can be almost as long as the body. Females lack the sword and grow larger and heavier, up to about 4.7 in (12 cm). Swordtails are sold in red, green, black, orange, tuxedo and lyretail forms. Wild fish are olive green with a red lateral stripe and live in flowing rivers and streams of Mexico, Guatemala, Belize and Honduras.
People love them because they are showy, hardy and always on the move. They suit beginners, but be aware that they grow bigger than platies, swim a lot, and males can be quite pushy with each other.
Care and tank setup
This is a large, active swimmer that needs at least a 30-gallon (115 L) tank, ideally around 3-4 ft (100-120 cm) long, for a small group.
- Males: the simplest setup is 1 male with 2-3 females. With two males the dominant one usually harasses the other; if you want several, keep at least three in a roomy tank to spread out the tension.
- Water: moderately hard to hard, neutral to alkaline pH, at 72-81 °F (22-27 °C), well oxygenated and with some current, which they enjoy.
- Lid: essential; swordtails are strong jumpers.
- Decor: hardy plants at the back and sides, a wide open swimming area and cover for females.
- Tank mates: mollies, platies, corydoras, bristlenose plecos, calm barbs, medium-sized tetras and other peaceful hard-water fish.
Avoid very small fish and dwarf shrimp, which an adult swordtail may eat. Do not pair them with bettas or long-finned guppies, which they may pester. And never release them into the wild: they are invasive in many warm regions.
Feeding
A hungry omnivore. Use a quality flake or pellet with plant content as the staple and add brine shrimp, daphnia, bloodworms and occasional blanched vegetables. Swordtails also graze algae. Feed twice a day without overdoing it, as they put on weight easily. With slower tank mates, make sure it does not hog the food; it is fast and always gets there first.
Breeding
A very prolific livebearer: after about 4 weeks of gestation a large female can drop anywhere from 20 to more than 80 fry, and she stores sperm for several broods. Adults eat the fry, so use plenty of floating plants or a roomy breeder box (or a separate tank) for the heavily pregnant female. Fry grow fast on powdered food and baby brine shrimp.
Compatible tank mates
Species from our database that share water parameters, size and temperament with the Swordtail. Calculated from the data in each profile.
Bristlenose pleco Ancistrus sp. 26 gal (100 L) · 72–81 °F (22–27 °C) 
Betta fish Betta splendens 7 gal (25 L) · 75–82 °F (24–28 °C) 
Bronze cory Corydoras aeneus 21 gal (80 L) · 72–81 °F (22–27 °C) 
Zebra danio Danio rerio 16 gal (60 L) · 64–77 °F (18–25 °C) 
Cherry barb Puntius titteya 16 gal (60 L) · 73–81 °F (23–27 °C) 
Tiger barb Puntigrus tetrazona 26 gal (100 L) · 72–79 °F (22–26 °C) 
Nerite snail Neritina natalensis 5 gal (20 L) · 72–82 °F (22–28 °C) 
Horned nerite snail Clithon corona 5 gal (20 L) · 72–82 °F (22–28 °C) 
Common goldfish Carassius auratus 79 gal (300 L) · 50–75 °F (10–24 °C) 
Panda cory Corydoras panda 16 gal (60 L) · 68–77 °F (20–25 °C) 
Guppy Poecilia reticulata 14 gal (54 L) · 72–82 °F (22–28 °C) 
Dwarf gourami Trichogaster lalius 16 gal (60 L) · 75–82 °F (24–28 °C) Check the compatibility of your whole tank →
What not to keep it with
Popular species you shouldn’t house with the Swordtail, and why.
- Discus: incompatible temperatures, incompatible pH, incompatible water hardness
- Oscar: one may eat the other due to size, incompatible temperaments
- Celestial pearl danio: one may eat the other due to size
- Cardinal tetra: incompatible pH, incompatible water hardness
- Ember tetra: one may eat the other due to size
- Amano shrimp: eats shrimp
- Cherry shrimp: eats shrimp
Recommended equipment
What you need to keep the Swordtail healthy, checked against Amazon stock.
Frequently asked questions
How many liters does a Swordtail need?
At least about 120 liters for a group of at least 3 fish. More space always helps keep the water stable.
What water temperature does the Swordtail need?
Between 22 and 27 °C, with a pH of 7 to 8.2.
What fish can live with the Swordtail?
Based on water, size and temperament, it fits with species such as Bristlenose pleco, Betta fish, Bronze cory, Zebra danio and Cherry barb. Use our compatibility calculator to check your whole tank.
Can the Swordtail be kept with shrimp?
Not recommended: because of its size or instinct, it will eat shrimp.
