Swordtails: The Livebearer With a Blade for a Tail

In this guide

Overview

The swordtail, Xiphophorus hellerii, gets its name from the sword-like extension on the lower edge of the male's tail fin, a feature absent in females. Native to Mexico and Central America, it is a close relative of the platy and shares much of its easy-going nature, though it grows larger, up to twelve centimetres for a mature male.

Popular colour forms in India include red, green, and the koi-patterned swordtail, which mixes orange, black and white.

Tank and water requirements

Given their adult size, swordtails need at least eighty litres for a small group, with more swimming room preferred since they are active fish. They share the same water preferences as mollies and platies, doing well in India's typically harder tap water.

A tight-fitting lid is worth having, since swordtails are known jumpers, particularly when startled or when a dominant male is chasing a rival.

Diet and behaviour

An omnivorous diet of flakes, pellets, and occasional live or frozen food keeps swordtails in good colour. They will also nibble algae and soft plants.

Two males in a small tank often clash over territory and females, so keeping one male with several females, or a larger group with more swimming space, avoids constant chasing.

Buying tips

• Priced similarly to mollies in most Indian shops, generally forty to a hundred rupees per fish
• Check that the sword extension is intact and not frayed, a sign of fin nipping or poor water quality at the shop
• A well-kept swordtail can live three to five years, longer than many hobbyists expect from a livebearer

An unusual quirk

Occasionally a female swordtail that has already bred and raised fry will later develop a sword and male colouring, a genuine sex reversal rather than a misidentification. It is a normal, if surprising, part of the species' biology, and not a sign of illness or poor water quality.

Article content © Ravi Teja. All rights reserved.