Swordtail Fish
The livebearer with the sword — a sleek, colorful fish with a dramatic tail extension that gives the breed its name. That distinctive male "sword" on the lower caudal fin, those endless color varieties. Complete guide: why Swordtails JUMP (lid mandatory!), the 1 male : 3 female ratio, and the Platy × Swordtail hybridization possibility.
📋 Species Overview
⚔️ The Male Sword — Sexual Dimorphism
Male Swordtails develop the elongated lower caudal fin "sword" at sexual maturity (3-4 months). This is a secondary sex characteristic — females lack it entirely. Males also have the gonopodium (modified anal fin) like all livebearers. The sword can be nearly as long as the body in well-bred specimens. 1 male : 3 females minimum — males constantly pursue females, and a lone female will be stressed to death by a single male's attention.
⚠️ Jumpers — Lid Is NON-NEGOTIABLE
Swordtails are notorious jumpers. They can launch themselves through a gap of just 2-3 cm. Every Swordtail tank MUST have a tight-fitting lid with no gaps. Countless Swordtails have been found dried up on the floor after jumping through a feeding hole or a gap around the filter. Also: Platies and Swordtails can hybridize (same genus, Xiphophorus). If you keep both together, you may get viable hybrids.