Emerald Eye Rasbora

The Emerald Eye Rasbora is a charming small rasbora reaching only 3.5 cm, making it a true nano aquarium species. Its common name refers to two of its most distinctive features: a vivid emerald-green iridescent spot positioned just above and behind the eye, and a dark ocellated spot at the base of the dorsal fin that becomes particularly visible from certain angles. The body is otherwise silvery to translucent with a faint yellowish lateral stripe. This combination of subtle body coloration and distinctive markings makes it a unique and appealing species in a small school. Native to the slow-moving to gently flowing, soft, and acidic blackwater streams of peninsular Malaysia and Sumatra, the Emerald Eye Rasbora is associated with peat swamp forest habitats and clear forest streams over sandy substrate. In the aquarium it adapts to a range of conditions within its tolerance range, although it shows best coloration and behavior in water on the softer, slightly acidic end of the spectrum. It is entirely peaceful and suitable for planted nano community setups. A school of eight or more allows full observation of its schooling behavior and social dynamics. It is an omnivore that accepts small aquarium foods readily.

Tank Setup A minimum of 40 liters for a school of six to eight. A planted nano setup with dark substrate, fine-leaved plants such as Java moss and Hemianthus, and some driftwood creates an ideal environment. Keep the middle section reasonably open for free swimming while providing planted refuges at the margins. Gentle filtration is appropriate — avoid strong currents that stress small schooling fish.

Water Parameters Maintain pH between 6.0 and 7.5, ideally slightly acidic. Temperature of 22–27°C is suitable. Soft to moderately hard water is appropriate; avoid hard, very alkaline conditions. If tap water is hard, consider mixing with soft or reverse-osmosis water. Maintain high water quality with weekly water changes of 20–25%.

Feeding A small omnivore requiring appropriately sized food. Offer crushed flake, micro-pellets, and small frozen or live foods such as baby brine shrimp, cyclops, and daphnia. Feed small amounts two to three times daily. Ensure food particles are fine enough for these small fish to consume effectively.

Tankmates Best kept with similarly small, peaceful nano species. Suitable companions include small danios, other nano rasboras, small tetras, pygmy corydoras, dwarf shrimp, and small peaceful loaches. Avoid any fish large enough to view them as prey or that may outcompete them for food.

Health and Maintenance Generally hardy for a small fish. Maintain stable water quality and avoid sudden parameter changes. Monitor for ich. Perform regular small water changes to prevent nitrate accumulation in a small aquarium.