Yucatan Molly

The Yucatan Molly (Poecilia velifera or P. petenensis depending on population) is a large wild-type sailfin molly from the coastal rivers and lagoons of Mexico's Yucatan Peninsula, where it inhabits warm, mineral-rich, often brackish waters. Males develop an enormous dorsal fin — the largest of any molly species — that they erect fully during courtship displays.

This species is significantly larger than the common aquarium molly and requires a spacious tank to thrive. In the right conditions, a mature male Yucatan Molly in full display is one of the most magnificent freshwater livebearers available to hobbyists.

Best kept with a small amount of salt (3–5 g/L) or in hard, alkaline freshwater with excellent filtration. Males are territorial with each other but peaceful towards other species.

Water: 24–30 °C, pH 7.5–8.5, GH 15–30; mild brackish conditions (up to 5 g/L salt) ideal. Tank: 200 L minimum; open swimming space; robust plants tolerant of salt. Feeding: Spirulina-based foods, algae wafers, quality flake, blanched greens; 2–3 meals daily. Breeding: Livebearer; 20–100 fry per brood; large males take time to develop full sail fin. Compatibility: Peaceful with other species; males territorial towards conspecifics.