Overview
The Emerald Eye Rasbora (Brevibora dorsiocellata), often called the Glow-eyed Rasbora, is a beautiful, small schooling fish belonging to the Cyprinidae family. They are highly sought after in the aquarium hobby for the stunning, reflective green patch over their eyes that appears to glow under aquarium lighting. They are excellent additions to peaceful community and planted tanks.
Distribution and Habitat
This species is native to Southeast Asia, specifically found in the Malay Peninsula and the Greater Sunda Islands of Borneo and Sumatra. They inhabit slow-moving rivers, peat swamps, and forest streams. These waters are typically tinted with tannins from decaying organic matter, making them soft and acidic, heavily shaded by the dense forest canopy above.
Description of Emerald Eye Rasbora
Body shape:
They possess a slender, streamlined, and slightly elongated body typical of many rasboras, designed for swift swimming in mid-water areas.
Color:
The body is predominantly silvery to slightly translucent or clear, with a subtle iridescent sheen. The most distinctive markings are the bright, glowing green-blue upper part of the eye and a prominent black spot on the dorsal fin.
Barbels:
Unlike some cyprinids, they do not possess prominent barbels.
Snout:
The snout is relatively short and slightly pointed, with a terminal mouth adapted for feeding on small invertebrates in the water column.
Eyes:
Their eyes are their namesake feature. The upper half of the iris contains a highly reflective, iridescent green/yellow patch that shines brilliantly, especially in dimly lit or tannin-stained water.
Fins:
The fins are mostly translucent. The dorsal fin features a striking, bold black blotch, often edged with white or pale yellow, which they frequently flick while swimming.
The Tail:
The caudal (tail) fin is deeply forked and clear, aiding in their agile and darting swimming movements.
Temper
These rasboras are incredibly peaceful and non-aggressive, making them a perfect candidate for a community aquarium with other similarly sized, docile species.
Sociality
They are a highly gregarious schooling species. They should always be kept in groups of at least 8 to 10 individuals. A larger school not only reduces their stress but also encourages a much tighter schooling behavior and better coloration.
Activity
They are highly active, mid-level swimmers. They spend the majority of their time darting around the open swimming spaces of the aquarium, often tightly grouped together.
Keeping and Caring for Emerald Eye Rasbora
Caring for these fish is generally straightforward, provided their water quality is maintained. They thrive in setups that mimic their natural, slightly acidic, and tannin-rich habitats.
Tank size:
A minimum tank size of 15 to 20 gallons is recommended to provide adequate swimming space for a proper school.
Water Parameters:
Temperature
They prefer tropical temperatures ranging from 20-25°C (68-77°F).
pH
A slightly acidic to neutral pH is ideal, typically between 5.0 and 7.5.
Hardness
Soft water is preferred, with a general hardness (GH) of 1-10 dGH.
Ammonia, Nitrite, Nitrate
Ammonia and Nitrite must always be 0 ppm. Nitrates should be kept as low as possible, ideally below 20 ppm, through regular water changes.
Lighting
Dim or subdued lighting is best. This not only mimics their natural shaded habitat but also makes their glowing eyes stand out significantly more.
Water flow
They prefer gentle to moderate water flow, similar to the slow-moving streams they originate from.
Decorations and Plants
A densely planted tank with plenty of open swimming space in the center is ideal. Driftwood, leaf litter (like Indian Almond leaves), and floating plants help create the perfect environment and provide beneficial tannins.
Diet
They are micropredators in the wild, feeding on small insects, worms, and zooplankton. In the aquarium, they are omnivorous and will readily accept high-quality crushed flakes, micro-pellets, and small live or frozen foods such as daphnia, baby brine shrimp, and cyclops.
Some Feeding Tips
Because of their small mouths, ensure all food is appropriately sized. Feed them small amounts 2-3 times a day, only what they can consume in a couple of minutes.
Breeding
Breeding is possible but requires a dedicated setup. They are egg-scatterers that show no parental care. To breed them, set up a dimly lit breeding tank with soft, acidic water and a mesh or spawning mop at the bottom to protect the eggs from being eaten. After spawning, the parents should be removed immediately. The fry are extremely tiny and will require infusoria or paramecium until they are large enough to accept microworms or baby brine shrimp.
Conclusion
The Emerald Eye Rasbora is a spectacular, active, and peaceful schooling fish. Their unique glowing eyes and tight schooling behavior make them a mesmerizing focal point in any planted or biotope aquarium. With straightforward care requirements, they are an excellent choice for both novice and experienced aquarists looking to add life and sparkle to their tanks.
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