Xiphophorus cortezi

Xiphophorus cortezi Rosen, 1960

Affiliation: northern swordtail

IUCN status: data deficient

Distribution: south of the Río Tampaón, including the Río Coy, Río Moctezuma / Río Axtla, Río San Pedro, and Río Candelaria in the Río Pánuco drainage, San Luis Potosí, Mexico

Known locations (existing/former): several

Type locality: Arroyo Matlapa at Comoca, 3,2 km north of Axtla, in the Río Pánuco Basin, San Luis Potosí, Mexico

Habitat description: Typically found in clear, fast-flowing streams and rivers with stable, spring-fed water conditions. The water temperature is stable, and the oxygen levels are high. The substrate is composed of small stones, gravel, and occasionally patches of fine sediment.

Biotope reports:

• none yet

Description: Medium size, slender-bodied fish, exhibiting distinct sexual dimorphism. Males typically display a more vibrant colouration, with an iridescent body that transitions from light blue to yellow near the tail. The dorsal fin is often pale yellow, often with black pattern, while the caudal fin is a striking, bright yellow, frequently adorned with smaller and larger black spots. Females are generally more subdued in coloration, with a pale yellowish to brownish body and a bold dark lateral stripe running from the head to the tail.

Variability:  There is minimal variability within natural populations. The overall body colour is consistent, with only subtle changes in the intensity of the yellow and blue hues among males. Some males have irregular black melanophores in caudal fins.

XWG status: not yet actively managed

Represented in aquaria: Not widely represented in aquaria. It is occasionally maintained by specialized breeders and research institutions.

Known issues: –

Known collections or populations:

• Río Huichihuayán, San Luis Potosí, Mexico
• Río Axtla, San Luis Potosí, Mexico

(if you have more information, please contact us at info@xipho.org – thanks!)