Celestichthys erythromicron

Celestichthys erythromicron, formerly classified as Microrasbora erythromicron and sometimes sold as the Emerald Dwarf Rasbora, is an exquisite micro fish from the shallow vegetated margins of Inle Lake in Myanmar. Its pale, translucent body is crossed by 10–14 vivid teal-blue vertical bars that stand out brilliantly against the lighter background, while the unpaired fins glow with intense red-orange pigmentation.

It is one of the smallest cyprinids in the hobby at just 2 cm, yet it is a surprisingly bold and active fish, with males engaging in regular display interactions — spreading their fins and intensifying their colours in brief territorial encounters. A large group of fifteen or more in a well-planted nano tank creates one of the most spectacular micro-fish displays possible.

The species' preference for the moderately hard, slightly alkaline waters of Inle Lake distinguishes it from most other nano cyprinids, which typically favour soft, acidic conditions. This unique water chemistry requirement must be met for long-term health and colour.

Water: Temperature 19–25°C, pH 7.0–8.0, GH 8–18; moderately hard, slightly alkaline water essential — unlike most nano cyprinids this species does not prefer soft acid water. Tank: Minimum 30 L nano planted tank; fine-leaved plants and moss; subdued lighting; very gentle sponge filtration. Feeding: Micro-pellets, crushed flake, rotifers, cyclops, and baby brine shrimp nauplii; only the smallest food items suit the tiny mouth. Breeding: Egg-scatterer over fine plants; fry are tiny; green water or commercial nano fry food required as first food. Compatibility: Peaceful with all nano species sharing similar water parameters; avoid soft-water nano fish; ideal with Microdevario erythromicron and nano shrimp.