Golden Wonder Killifish (Aplocheilus lineatus 'Gold')

The Golden Wonder Killifish (Aplocheilus lineatus 'Gold') is the ornamental golden strain of the Striped Panchax (Aplocheilus lineatus), selectively bred from wild South Asian stock for maximized golden-yellow coloration. It is by far the most commonly available killifish in mainstream aquarium retail, making it the entry point for most hobbyists into the killifish group.

Males are vividly colored: a warm golden to brass-yellow body base is overlaid with rows of iridescent blue-green, red, and orange spots across the flanks and fins that catch light brilliantly. The upturned mouth is adapted for surface feeding. Females are less ornate but share the golden base with reduced spotting. Both sexes are larger than most hobby killifish, reaching 8–10 cm.

In nature, A. lineatus inhabits standing and slow-moving freshwater bodies, rice paddies, ponds, and coastal lagoons across peninsular India and Sri Lanka. It tolerates a remarkably wide range of water conditions including slightly brackish water — a reflection of its coastal distribution.

Golden Wonder Killifish are ambush surface predators with lightning-fast reflexes. They spend most of their time hovering motionless near the water surface before striking at prey — a behavior pattern that makes them fascinating to observe. Despite their predatory nature, they are peaceful toward fish too large to eat and can be kept with appropriate community species.

Golden Wonder Killifish are among the hardiest aquarium killifish, tolerating pH 6.0–8.0, hardness 5–20 dGH, and temperatures 22–28°C. They can tolerate some aquarium salt (1–3 tsp per 10L) and even slightly brackish conditions, making them unusually flexible.

A minimum 80-liter aquarium suits a pair or small group. Dense floating vegetation (Salvinia, Pistia, Riccia) is essential — it provides security, spawning sites, and replicates their natural heavily vegetated surface habitat. A tight lid with no gaps is absolutely critical, as they are powerful jumpers.

Feed primarily surface and mid-water foods: floating pellets, live or frozen bloodworms, earthworms, brine shrimp, daphnia, and small insects. They are enthusiastic surface feeders that may initially ignore sinking foods. Hand-feeding with tongs is possible and helps tame them.

Golden Wonder Killifish will consume any fish small enough to fit in their mouths — avoid nano fish, small tetras, guppies, shrimp, and other tiny inhabitants. Suitable tankmates include larger barbs (Tiger, Rosy), medium cichlids, large livebearers, and other robust medium to large fish.

Males can be territorial with each other in small spaces. Maintain appropriate space (150+ liters for multiple males) or keep single males. Water changes of 25–30% weekly maintain condition and encourage spawning.