Lyretail Swordtail

Looks how to spot one

Scales and fins

The lyretail swordtail has a sleek, torpedo-shaped body typical of swordtails, but its fins are dramatically elongated. The upper and lower rays of the caudal fin extend into long, sweeping curves that resemble a lyre, and the dorsal fin is often enlarged and veil-like. Males also have the classic sword-like extension on the lower part of the tail.51

Personality what they are like

Lyretail swordtails are generally peaceful and active, spending most of their time exploring the mid-water column. Males can be territorial towards each other, so it is best to keep only one male or provide plenty of hiding places in a larger tank. Their long fins make them slower and clumsier swimmers than the wild type, so they should not be housed with fin-nipping species.14

Daily activity how busy a day looks

They need plenty of open swimming space but prefer gentler water currents than the wild swordtail to avoid tiring their delicate fins. A tank of at least 20 to 30 gallons is recommended.13

Grooming and care the hands-on bits

Their long fins are prone to fin rot and fraying, so pristine water quality is essential. Avoid sharp decorations and aggressive tankmates that might nip at the fins. Regular water changes and a gentle filter help keep them healthy.1

Home where they are happiest

They require hard, alkaline water with a pH of 7.0 to 8.3 and a temperature between 64 and 82 °F. A well-planted aquarium with plenty of swimming room and a secure lid is ideal. Acidic water can damage their long fins.31

Food basics what goes in the bowl

Omnivorous. They thrive on high-quality flake or pellet food, supplemented with frozen or live foods such as brine shrimp, daphnia and bloodworms. Vegetable matter like spirulina or blanched spinach should also be offered.43

Company who they like around

They are social fish that do best in groups of three or more. Males can be aggressive towards each other, so only one male should be kept unless the tank is large and well planted. They are compatible with other peaceful community fish, but avoid fin-nippers like tiger barbs or serpae tetras.41

The story where it all began

The lyretail swordtail is a selectively bred variety of the green swordtail, Xiphophorus hellerii. It was first developed by Florida fish farmer Don Adams, who noticed a mutation that caused the upper and lower rays of the caudal fin to elongate into a lyre shape. This trait was then stabilised through selective breeding. Unlike the wild swordtail, which has a simple pointed tail, the lyretail has all its fins extended, giving it a graceful, flowing appearance. Because of the extreme fin elongation, many lyretail males become functionally sterile, so breeders often use normal males to fertilise lyretail females. The variety is more valuable than the common swordtail due to its striking beauty.516

Recognised by the official bits

Center for Tropical and Subtropical Aquaculture

The lyretail trait was first identified by Florida fish farmer Don Adams and has since been established as a distinct variety.5