Marigold Swordtail (Xiphophorus hellerii var.)

The Marigold Swordtail is an ornamental color variety of Xiphophorus hellerii (the Green Swordtail), a livebearer native to the Atlantic slope river systems of Mexico and Central America — primarily from the Nautla River in Veracruz, Mexico south through Guatemala and Belize. Selective breeding since the early 20th century has produced a vast array of color varieties, of which the 'Marigold' variant displays warm golden-orange to yellow-orange body coloration.

The defining feature of male swordtails is the elongated lower caudal fin ray that extends well beyond the tail fin — the 'sword' — often with a yellow-gold border. This sword is absent in females. Males also tend to be slightly slimmer than the rounder, larger females. In the Marigold variety, the sword is typically golden-yellow, complementing the warm body coloration.

Females of all swordtail varieties are larger than males, may develop a small rudimentary sword with age, and display the characteristic gravid spot near the anal fin. As livebearers, females give birth to large broods of 20–100+ fully formed fry after 4–6 weeks of gestation.

Swordtails are among the most popular livebearers in the hobby alongside guppies, platies, and mollies. They are hardy, adaptable, and long-lived compared to many livebearer species.

Marigold Swordtails are very adaptable: pH 7.0–8.5, hardness 10–25 dGH, and temperatures 22–28°C. They prefer slightly hard, neutral to alkaline water reflecting their Central American highland river origins.

A minimum 80-liter aquarium with ample horizontal swimming space suits a small group. Dense plantings around the tank perimeter provide cover, particularly for females being courted and for newborn fry. Moderate current and good oxygenation are beneficial — swordtails are active, strong swimmers.

Feed a varied omnivorous diet: quality flake food, pellets, vegetable flakes, algae wafers, spirulina, daphnia, brine shrimp, and bloodworms. Providing plant-based foods prevents them from nibbling on aquatic plants.

Males may aggressively court females. Maintain at least 2–3 females per male to distribute attention. Males may also show mild aggression toward each other — ensure adequate space. Compatible with other livebearers (mollies, platies), medium tetras, corydoras, barbs, and most peaceful community fish.

Breeding is prolific — provide dense plant cover for fry survival or a separate breeding tank. Separate expectant females shortly before birth to protect fry. Population management may be needed in established tanks. Water changes of 25–30% weekly maintain water quality.