Sheepshead Swordtail

The sheepshead swordtail is one of the species in the genus Xiphophorus that carry no sword. Large males develop a distinct fleshy hump behind the head; together with the tall dorsal fin and the dark vertical bars on the body, this hump creates the sheep's-head look that gives the species its name. Where it meets a sworded relative (X. malinche) in the wild, it forms natural hybrid zones, which is why it is often studied in evolutionary research.

• At least 100 liters and an 80 cm tank length for a small group.
• 21–24°C, pH 7–8, moderate hardness; avoid warm, still water.
• Gentle to moderate flow, high oxygen, stones and clumps of plants.
• A tight lid; 25–30% water change weekly.

Omnivorous. Flakes and granules, spirulina food, frozen daphnia, brine shrimp and mosquito larvae. It grazes on algae and biofilm on stones.

Peaceful toward other species. Large males display to each other by raising their humps and dorsal fins, and chase smaller males. Visual barriers reduce this tension.

Good companions: peaceful fish suited to cool water, zebra danios, corydoras, Ancistrus plecos, shrimp.

Avoid: other Xiphophorus species (hybridization), fin-nipping barbs, large and aggressive species.