What tank size does a Swordtail Fish need?
Swordtails are active, fast-swimming livebearers that reach 4–6 inches (10–15 cm) including the distinctive caudal sword of the male. They need a tank with adequate horizontal swimming space — a minimum of 20 gallons for a small group, with 30 gallons recommended.
Keep swordtails in a group ratio of 1 male to 2–3 females. Male swordtails persistently chase females; having more females per male distributes the mating pressure and prevents a single female from being constantly harassed. Groups of all males are generally peaceful and also work well.
Swordtails are livebearers that reproduce readily in any mixed-sex tank. If you are not set up to manage fry, consider keeping an all-male group or only females. A 30-gallon long tank with 5–6 swordtails is an active, colourful display tank that is easy to maintain.
Unlike some livebearers, swordtails are not brackish-water fish. They prefer slightly alkaline freshwater (pH 7.0–8.3) and temperature stability over warm temperatures. A simple community tank setup suits them well.
Frequently asked questions
What size tank do swordtails need?
Swordtails need a minimum of 20 gallons for a small group. A 30-gallon tank is the recommended size for a comfortable swordtail community. Swordtails grow to 4–6 inches and are active, fast-swimming fish that benefit from a long tank with horizontal swimming space.
How many swordtails can I keep in a 20-gallon tank?
A 20-gallon tank can hold 4–5 swordtails comfortably (roughly 5 gallons per fish accounting for their activity level and adult size). Keep a ratio of 1 male to 2–3 females if mixing sexes. All-male groups of 4–5 swordtails in a 20-gallon tank are peaceful and colourful.
Can swordtails live in a 10-gallon tank?
A 10-gallon tank is not recommended for swordtails. They grow to 4–6 inches and are very active swimmers that need horizontal space. A 10-gallon tank is too small for a proper group, and the limited space increases aggression between males and stress on females from constant male attention.
Do swordtails need to be in groups?
Swordtails benefit from being kept in small groups of 4–6 fish with a ratio of 1 male to 2–3 females. This distributes mating pressure so no single female is constantly chased. All-male groups of swordtails are usually peaceful. Keeping a lone swordtail is not ideal, but a single swordtail in a peaceful community tank can do well.
Can male and female swordtails be kept together?
Yes, but plan carefully. Male swordtails persistently court females, which can stress individual females if there are too few. The standard ratio is 1 male to 2–3 females. Swordtails are livebearers and will produce fry in a mixed-sex tank — be prepared to manage the population by separating or rehoming fry, or keep an all-male or all-female group.
More Swordtail Fish resources