Chocolate Australe

Chocolate australe is a color form of Aphyosemion australe, commonly called the lyretail panchax or Cape Lopez lyretail, a small egg-laying killifish native to forest streams around Cape Lopez, Gabon, in West-Central Africa. It belongs to the family Aplocheilidae within the order Cyprinodontiformes. The wild-type coloration is a rich brown, referred to as "chocolate" in the aquarium hobby, and is distinguished from other Aphyosemion color forms by its warm brown base rather than gold or red tones. Males develop an elegant, elongated lyre-shaped tail as they mature, a hallmark of the genus. It is among the most widely kept and long-established killifish species in the aquarium trade.

Chocolate australe killifish reach about 5-6 cm as adults.

• Body: slender and elongated, typical of stream-dwelling Aphyosemion killifish
• Male coloration: rich chocolate-brown flanks with scattered fine carmine-red spots and sometimes faint dark blotching
• Tail: elongated, lyre-shaped, with orange-yellow edging that becomes more pronounced with age
• Female coloration: plain tan-brown with rounded, unextended fins

The brown "chocolate" base color separates this form from the gold and red color varieties also seen within Aphyosemion australe; the elongated lyretail shape distinguishes the species from round-tailed killifish genera.

This species is native to slow-moving forest streams, swamps, and shaded pools in the coastal lowlands around Cape Lopez, Gabon, in West-Central Africa. It favors warm, soft, often tannin-stained water beneath dense rainforest canopy, with abundant leaf litter and overhanging vegetation providing cover. Unlike annual killifish from seasonal East African pools, Aphyosemion australe lives in more permanent water bodies and does not need to survive complete drying, allowing a longer natural lifespan. It typically stays near the surface and among submerged roots and debris.

Chocolate australe killifish are calm, peaceful fish that feed near the surface and among leaf litter on small insects, crustaceans, and other invertebrates. Males display their extended lyretail and coloration during courtship and mild territorial disputes with rival males, though aggression is generally low compared to many other killifish. Spawning occurs among fine vegetation or leaf litter, where eggs are scattered and adhere until hatching roughly two to three weeks later; the species is not annual and does not require diapause. As a stream-dwelling insectivore, it contributes to natural control of aquatic insect populations in its native forest habitat.