Green Swordtail

Green Swordtail (Eng.), Pez Espada (Sp.), Xiphophorus hellerii (Sci.), introduced species – Puerto Rico island rivers and streams.

Photo © 2004, Steven Kazianis, Texas State University. Information compiled by Alan Mowbray, Interpretive Media Writer, EYNF/LEF

General Information

Taxonomy: Class – Actinopterygii, Order – Cyprinodontiformes, Family – Poeciliidae, Genus – Xiphophorus, Species – X. hellerii. Introduced species, Puerto Rico.

Description

Green swordtail males grow to a maximum overall length of 5.5 inches (14 centimeters) while females are slightly larger, typically reaching a maximum length of 6.3 inches (16 cm). The "swordtail" name derives from the elongated lower lobe of the male's tailfin. Differences between sexes are moderate – the female is slightly larger than the male but lacks the "sword". Color is olive green, with a red or brown lateral stripe and speckles on the upper (dorsal) and, sometimes, caudal (tail) fins. The male's "sword" is yellow, edged in black below.

Habits

X. hellerii is omnivorous; its diet includes plants and small crustaceans, insects, and annelid worms. The elongated tail (caudal) fins of males have been found to significantly affect their chances at mating. The presence of a well-endowed male spurs the maturity of females while it inhibits the maturity of juvenile males in the vicinity of the well-endowed male. They are livebearers – young emerge free swimming. Like the guppy, the Green Swordtail is a prolific breeder – females typically give birth to 20 to 80 young every 28 days.

Habitat

The Green Swordtail prefers heavily vegetated, swift flowing rivers and streams, but can also be found in warm springs and pools.

Conservation

X. hellerii is currently classified as “GS - Secure” in the IUCN Red Data List.

Where to look for this animal in the EYNF

In rivers and streams adjacent to nature trails.