Threadfin Rainbowfish

The threadfin rainbowfish (Iriatherina werneri) is the sole species in its genus, native to shallow swamps, flooded grasslands, and slow-moving streams from the Fly River system in southern New Guinea through the Cape York Peninsula of northern Queensland, Australia. Growing to 4–5 cm, males develop extraordinary elongated fin rays on the dorsal, anal, and caudal fins — extensions so delicate and flowing that the fish has been described as 'an underwater butterfly.' The effect in a well-planted, calm aquarium is genuinely otherworldly. Water conditions of pH 6.5–7.5 at 24–28°C are appropriate. The primary care challenge is protecting the gossamer fins: even moderate water current shreds them irreparably, making sponge filters or extremely gentle flow sources essential. Any fin-nipping fish is strictly incompatible. Their tiny mouths require micro-sized foods exclusively: powdered fry foods, baby brine shrimp nauplii, and micro worms. Breeding on fine plants is achievable, though fry are extremely small and require infusoria for initial feeding. A fish of exceptional elegance and fragility, best suited to a purpose-designed, species-appropriate nano or botanical aquarium.

Source: Wikipedia (CC BY-SA 4.0)

Frozen brine shrimp, infusoria, micro pellets