Emerald Eye Rasbora Care Guide: Complete 2026 Species Overview

The Emerald Eye Rasbora (Brevibora dorsiocellata) is a captivating nano fish that has earned a devoted following among aquarists who appreciate subtle beauty and peaceful tank inhabitants. Native to the forest peat swamps and blackwater streams of Southeast Asia, these small cyprinids shimmer with metallic silver bodies and striking emerald-green eyes that seem to glow under the right lighting conditions. Their compact size and tight schooling behavior make them ideal candidates for planted aquariums and blackwater biotope setups.

What sets this species apart from other small rasboras is their remarkably calm disposition and tight shoaling behavior. While many nano fish can be flighty or aggressive, Emerald Eye Rasboras move through the water column as cohesive groups, rarely bickering or displaying territorial behavior when kept in adequate numbers. Their preference for dimly lit tanks with soft, acidic water mirrors their natural habitat in the leaf-strewn streams of Borneo, Sumatra, and the Malay Peninsula.

Whether you are setting up your first community tank or adding to an established aquascape, these fish offer an excellent balance of visual appeal and manageable care requirements. In this comprehensive guide, you will learn everything needed to keep Emerald Eye Rasboras healthy and thriving, from water parameters and tank setup to breeding techniques and compatible tank mates. For those considering alternatives, you might also explore our guides on Chili Rasbora care or the popular Harlequin Rasbora.

Species Summary

Emerald Eye Rasboras belong to the family Cyprinidae and represent one of the more visually striking yet understated members of the rasbora group. These fish have undergone taxonomic revision and are properly classified as Brevibora dorsiocellata, distinguishing them from other rasbora species you might encounter in the aquarium trade. Understanding their scientific classification helps clarify why they require specific water conditions and how they differ from lookalike species.

Scientific Classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Cypriniformes
Family:	Cyprinidae
Genus:	Brevibora
Species:	B. dorsiocellata
Common Names
Emerald Eye Rasbora, Kubota's rasbora, green-eyed rasbora, blue-eye rasbora
Origin and Distribution
Native to:	Borneo, Sumatra, southern Thailand, Malay Peninsula
Habitat:	Blackwater forest streams, peat swamps, leaf-strewn tributaries
Physical Characteristics
Size:	Up to 2 inches (5 cm), typically 1.2-1.5 inches
Lifespan:	4-6 years in captivity
Coloration:	Metallic silver body, emerald eyes, yellow dorsal fin with black eyespot
Care Parameters
Temperature:	68-79°F (20-26°C)
pH:	6.0-7.5
General Hardness:	3-12 dGH
TDS:	18-179 ppm
Tank Size:	Minimum 10 gallons for 6 fish
Diet:	Omnivore
Temperament:	Peaceful, social, active
Care Level:	Moderate
Breeding:	Egg scatterer, constant spawner

Do not confuse Emerald Eye Rasboras with Emerald Dwarf Rasboras (Microrasbora erythromicron or Celestichthys erythromicron), which are a completely different species despite the similar common name. If you are uncertain about identification, consult our Emerald Dwarf Rasbora care guide for comparison.

Emerald Eye Rasbora Appearance

Emerald Eye Rasboras display an elongated, slender body shape typical of the rasbora family but with distinctive characteristics that make them instantly recognizable. Their base coloration features a shimmering silver to olive-gold body that reflects light beautifully as they move through the water. The most distinctive feature is the brilliant emerald-green eye that gives this species its common name, creating a striking contrast against their metallic body color.

The dorsal fin deserves special attention, as it features a vivid yellow base coloration with a prominent black spot in the center, technically referred to as a dorsal eyespot. This black spot serves a purpose in nature, potentially confusing predators about which end of the fish is the head. Dark vertical stripes run from the base of the dorsal fin to the caudal peduncle, adding another layer of visual interest. The remaining fins are typically translucent or hyaline, allowing the body coloration to remain the focal point.

Emerald Eye Rasbora Size and Growth Rate

Adult Emerald Eye Rasboras reach a maximum length of approximately 2 inches (5 cm), though most specimens in home aquariums stabilize around 1.2 to 1.5 inches (3-3.5 cm). This modest size makes them ideal inhabitants for nano tanks and smaller community setups where larger fish would be inappropriate. Their slim, torpedo-shaped profile means they occupy minimal swimming space compared to deeper-bodied species.

Growth occurs relatively quickly in the first six months of life. Juveniles added to a well-maintained tank with proper nutrition will reach near-adult size within this timeframe. Females typically grow slightly larger than males and develop rounder bellies, particularly when carrying eggs. There is minimal size difference between wild-caught and captive-bred specimens, as the species remains relatively consistent in dimensions across populations.

Sexual Dimorphism

Distinguishing male from female Emerald Eye Rasboras becomes easier as the fish mature. Females are noticeably larger and possess rounder, fuller bodies, especially when viewed from above. Their bellies swell noticeably when gravid with eggs, giving them a distinctly plumper appearance than their male counterparts.

Males tend to be slightly smaller and more streamlined overall. During breeding periods, males display enhanced coloration, particularly in the caudal fin, which can develop a reddish or orange hue. This color intensification helps signal readiness to spawn and is one of the more reliable indicators for sexing these fish when attempting to establish breeding groups.

Emerald Eye Rasbora Lifespan

With proper care and stable water conditions, Emerald Eye Rasboras can live between four to six years in captivity. Some aquarists report individuals reaching the upper end of this range when maintained in soft, acidic water that closely mimics their natural habitat. Lifespan in the wild is likely shorter due to predation, habitat degradation from palm oil expansion, and environmental pressures.

Several factors influence longevity in home aquariums. Water quality remains paramount, as these fish are sensitive to elevated nitrates and sudden parameter swings. A varied diet rich in live and frozen foods supports immune health. Stress reduction through appropriate schooling numbers and compatible tank mates also contributes to extended lifespans. Poor water conditions or aggressive tank mates can significantly reduce their expected lifespan.

Emerald Eye Rasbora Breeding

Emerald Eye Rasboras are constant spawners that will readily breed in well-maintained aquariums without requiring the extreme triggers some other species demand. They are egg scatterers that deposit adhesive eggs among fine-leaved plants or spawning mops. Understanding their breeding behavior allows aquarists to either raise fry successfully or manage population growth in community tanks.

To encourage spawning, condition adult fish with high-quality live and frozen foods for one to two weeks. Bloodworms, daphnia, and brine shrimp help bring females into breeding condition. Provide a spawning setup with Java moss, Taxiphyllum, or a purpose-built spawning mop where eggs can adhere away from hungry adults. Water parameters should be on the softer, more acidic end of their tolerance range, with temperatures around 75-78°F.

Spawning typically occurs in the morning hours. Females scatter eggs among the plants or mop while males fertilize them externally. Adult fish show minimal parental care and will consume their own eggs if given the opportunity. For dedicated breeding, remove adults after spawning or maintain them in heavily planted tanks where some eggs escape predation. Eggs hatch within 3-5 days depending on temperature.

Fry require microscopic foods for their first meals. Infusoria and Paramecium cultures provide essential nutrition during the first week. As they grow, transition to microworms and newly hatched baby brine shrimp. Maintain excellent water quality with frequent small water changes, as fry are sensitive to pollutants. With proper feeding and clean water, fry reach juvenile size within two months and can be integrated with adult populations.

For those interested in similar breeding projects, our Cherry Shrimp care guide covers another rewarding breeding endeavor that pairs well with rasbora tanks.

Emerald Eye Rasbora Behavior and Temperament

Emerald Eye Rasboras are peaceful, social fish that display some of the tightest schooling behavior among nano aquarium species. They occupy the middle to upper water column, moving as synchronized groups that can be mesmerizing to watch. Unlike some rasboras that loosely associate, Emerald Eyes typically maintain close proximity to one another, creating impressive shoaling displays when kept in adequate numbers.

These fish can be skittish, particularly when first introduced to an aquarium or when kept in groups smaller than recommended. Sudden movements around the tank or bright lighting may send them darting for cover. This shyness diminishes as they settle and feel secure in their environment. Forum reports consistently note that groups of ten or more display the most confident behavior, rarely hiding and constantly maintaining their tight formation.

Within their own species, Emerald Eye Rasboras show minimal aggression. There is rarely bickering, chasing, or territorial disputes between individuals. This makes them ideal for community setups with other peaceful species. They are not fin nippers and generally ignore slow-moving tank mates. Their calm demeanor extends to their feeding behavior, though this can become a disadvantage if housed with more boisterous eaters.

Emerald Eye Rasbora Availability

Emerald Eye Rasboras are moderately available in the aquarium trade, though not as ubiquitous as tetras or guppies. Most well-stocked local fish shops carry them seasonally, and online retailers consistently offer healthy specimens shipped directly to your door. Their popularity has increased in recent years as nano tank enthusiasts discover their appeal.

Pricing typically ranges from $2.80 to $9.99 per fish depending on size, source, and shipping costs. Buying in groups of six or more often reduces the per-fish cost and is recommended anyway given their schooling nature. Major online sources include LiveAquaria, Aqua Huna, and specialty tropical fish retailers like Wet Spot Tropical Fish. Local aquarium clubs sometimes offer captive-bred specimens at swap meets.

When selecting fish, look for active individuals with bright coloration and clear eyes. Avoid specimens that appear sluggish, have clamped fins, or show dull coloration. Examine the holding tank water quality; cloudy water or visible waste accumulation suggests poor retailer maintenance that may have stressed the fish. Ask about the retailer’s acclimation process and quarantine procedures before making a purchase.

Emerald Eye Rasbora Care Guide

Caring for Emerald Eye Rasboras successfully requires understanding their natural habitat and recreating those conditions in your aquarium. These fish originate from blackwater streams and forest peat swamps where tannins from decaying vegetation stain the water brown, pH remains acidic, and light penetration is minimal. While they adapt to standard community tank conditions, they display their best colors and behavior when kept in soft, acidic water with appropriate environmental enrichment.

The most critical aspect of their care involves maintaining stable water parameters and appropriate group sizes. As schooling fish, Emerald Eye Rasboras require groups of at least six individuals to feel secure, though ten or more produces noticeably better behavior. Sudden changes in water chemistry or temperature stress these fish considerably, so acclimate new arrivals carefully and maintain consistent maintenance schedules.

Feeding is straightforward thanks to their omnivorous diet and willingness to accept most prepared foods. However, variety remains important for long-term health and coloration. A mix of high-quality flakes or micro pellets supplemented with frozen or live foods provides complete nutrition. Avoid overfeeding, as uneaten food degrades the water quality these sensitive fish require.

For aquarists interested in other rasbora species, our guide to the 10 popular types of rasboras provides comparison options that might suit different tank sizes or water parameters.

Emerald Eye Rasbora Tank Size

The minimum tank size for Emerald Eye Rasboras is 10 gallons when keeping the recommended minimum group of six fish. This provides adequate swimming space for their schooling behavior while maintaining stable water parameters. However, a 20-gallon long or larger tank offers significant advantages for both fish behavior and maintenance ease.

Larger tanks accommodate bigger schools, which dramatically improves the fish's confidence and display quality. A 20-gallon tank comfortably houses 10-12 Emerald Eye Rasboras along with appropriate tank mates and aquascaping. The increased water volume also buffers against parameter fluctuations, providing the stability these sensitive fish prefer. Long tanks are preferable to tall tanks, as rasboras utilize horizontal swimming space more than vertical.

Emerald Eye Rasbora Tank Conditions

Creating optimal tank conditions for Emerald Eye Rasboras means replicating their blackwater stream habitat as closely as practical. Water temperature should remain between 68-79°F (20-26°C), with the middle of this range being ideal. They tolerate cooler temperatures better than many tropical species, making them suitable for unheated tanks in climate-controlled homes.

The pH range of 6.0-7.5 accommodates their adaptable nature, though they display the best coloration and breeding activity at the lower end of this spectrum. General hardness should stay between 3-12 dGH, with softer water preferred. TDS (Total Dissolved Solids) readings between 18-179 ppm align with their natural conditions. For dedicated blackwater biotopes, driftwood and leaf litter release tannins that naturally soften water and create the tea-colored tint these fish evolved in.

Plant selection should focus on species that thrive under the dim lighting Emerald Eye Rasboras prefer. Cryptocoryne, Microsorum (Java fern), Anubias, and Taxiphyllum (Java moss) all perform excellently in these conditions. These plants also provide the cover and security that helps reduce skittish behavior. Leaf litter, such as Indian almond leaves or oak leaves, adds authenticity to the biotope while supporting beneficial biofilm growth that fry can graze upon.

For additional planted tank inspiration, consider our Neon Tetra care guide, which covers similar blackwater biotope requirements for another popular schooling fish.

Filtration

Filtration for Emerald Eye Rasbora tanks should focus on gentle water movement and biological stability rather than powerful mechanical filtration. Sponge filters serve dual purposes excellently: they provide gentle, diffused flow that does not stress these small fish while offering massive surface area for beneficial bacteria colonization. This biological filtration is crucial in blackwater setups where decaying botanicals contribute organic load.

Hang-on-back or canister filters work well if outflow is baffled to reduce current strength. Strong flow pushes these small fish around the tank unnecessarily and prevents them from displaying natural swimming patterns. Position filter outflows to create gentle circulation rather than strong directional currents. For breeding setups, sponge filters are nearly essential, as they prevent fry from being drawn into filter intakes while maintaining water quality.

Regular filter maintenance prevents the buildup of organic waste that can acidify water too dramatically or harbor harmful bacteria. Rinse mechanical media in old tank water during water changes to preserve beneficial bacterial colonies. Replace chemical filtration media, such as activated carbon, according to manufacturer schedules to ensure optimal pollutant removal.

Lighting

Dim lighting suits Emerald Eye Rasboras best, replicating the forest canopy shade of their native streams. Bright aquarium lighting causes stress and washed-out coloration in these fish. LED fixtures with adjustable brightness or those designed for planted tanks with dimming capabilities allow precise control over illumination levels.

Floating plants provide natural light diffusion and are highly recommended for Emerald Eye Rasbora tanks. Species like water sprite, frogbit, or salvinia create dappled lighting effects while improving water quality through nitrate uptake. The security provided by overhead cover significantly reduces skittish behavior, allowing these fish to display more frequently in open water.

Aquascape lighting schedules should incorporate a ramp-up and ramp-down period using programmable timers. Sudden illumination changes startle these sensitive fish. Gradual dawn and dusk simulations create a more natural environment and reduce stress-related hiding behavior.

Decoration and Hardscaping

Tank decoration for Emerald Eye Rasboras should emphasize natural materials that create hiding places and visual barriers. Driftwood pieces, particularly those with interesting shapes or holes, provide refuge and surface area for biofilm growth. Dark-colored stones can be arranged to create caves and territories without harsh edges that might injure these delicate fish.

Substrate selection significantly impacts the overall aesthetic and water chemistry. Soft, sandy substrates in dark colors best replicate their natural habitat. Black or dark brown aquarium sand creates a pleasing contrast that makes the silver bodies and emerald eyes of these fish stand out dramatically. Avoid sharp gravel that could damage their sensitive barbels while foraging.

Leaf litter represents the finishing touch for authentic blackwater biotope setups. Indian almond leaves, oak leaves, or commercial blackwater extracts add tannins that tint water brown while providing antimicrobial benefits. These botanicals also serve as food sources for infusoria and microorganisms that fry consume. Replace decomposing leaves every few months to maintain the biotope aesthetic and benefits.

Live Plants

Plant selection for Emerald Eye Rasbora tanks must account for their dim lighting requirements and need for cover. Cryptocoryne species thrive in these conditions, offering broad leaves that serve as resting platforms and fry hiding spots. Their slow growth and minimal maintenance needs make them ideal for blackwater setups where water changes are conducted less frequently.

• Cryptocoryne wendtii and related varieties offer excellent cover in dim conditions
• Java Fern (Microsorum pteropus) attaches to driftwood and requires minimal light
• Anubias species provide slow-growing, durable foliage perfect for shaded areas
• Bolbitis heudelotii adds fine texture and thrives in cooler, softer water
• Vallisneria can create background screens if lighting permits moderate growth

Floating plants deserve special mention for their utility in these setups. Water sprite, frogbit, and duckweed all thrive under standard aquarium lighting while significantly dimming illumination for the fish below. Their root systems also provide additional grazing surfaces and hiding spots for fry. For more planted aquarium guidance, explore our Bladder Snail guide, which discusses ecosystem balance in planted tanks.

Hiding Places

Providing adequate hiding places is essential for Emerald Eye Rasbora welfare, particularly during the initial acclimation period or when kept in smaller groups. Caves formed by driftwood, rock structures, or commercial ceramic hides give these skittish fish secure retreats when startled. Dense plant thickets serve similar purposes while maintaining the natural aesthetic.

The strategic placement of hiding spots matters as much as their presence. Position some refuge near the tank front where fish can observe their surroundings while feeling secure. Additional caves toward the back provide deeper security for more timid individuals. Over time, as the fish settle and recognize feeding routines, they will venture out more frequently even without immediate cover nearby.

Water Changes

Regular water changes maintain the water quality essential for Emerald Eye Rasbora health. Aim for 25-30% water changes every two weeks in established, well-filtered tanks. In newer setups or heavily stocked community tanks, weekly water changes of similar volume prevent the accumulation of nitrates and dissolved organic compounds that stress these sensitive fish.

Always match replacement water parameters closely to the existing tank conditions. These fish react poorly to sudden pH swings or temperature shocks. Treat all tap water with a quality dechlorinator that neutralizes chlorine, chloramine, and heavy metals. For blackwater setups, replace botanicals during water changes to maintain consistent tannin levels.

Tank Maintenance

Routine tank maintenance keeps Emerald Eye Rasboras healthy and their environment stable. Use an aquarium-safe sponge or scraper to clean algae from glass surfaces during water changes, taking care not to disturb the fish excessively. Gently vacuum the substrate to remove accumulated waste without uprooting plants or disrupting the biological balance of established tanks.

Clean filter media in old tank water rather than tap water to preserve beneficial bacteria. Never replace all filter media simultaneously; stagger changes to maintain biological filtration capacity. Monitor water parameters weekly with liquid test kits, particularly pH, ammonia, nitrite, and nitrate levels. Document readings to identify trends before they become problems.

Emerald Eye Rasbora Common Possible Diseases

Emerald Eye Rasboras are generally hardy when kept in appropriate conditions, but they remain susceptible to common aquarium diseases like all freshwater fish. Prevention through quarantine, proper nutrition, and stable water quality remains more effective than treatment. Recognizing disease symptoms early allows for prompt intervention and better outcomes.

• Ich (Ichthyophthirius multifiliis): White spots resembling salt grains appear on the body and fins. Affected fish may rub against objects and display rapid breathing. Treatment involves gradually raising water temperature to 86°F while administering appropriate ich medication. Increase surface agitation during treatment to maintain oxygen levels.
• Fin Rot: Frayed or disintegrating fin edges, often with white or red margins, indicate bacterial infection. Poor water quality usually underlies this condition. Water changes and aquarium salt can help mild cases; severe infections require antibiotic treatment under veterinary guidance.
• Swim Bladder Disease: Affected fish struggle with buoyancy, floating uncontrollably or sinking to the bottom. Causes include overfeeding, constipation, or bacterial infection. Fasting for 24-48 hours followed by feeding cooked, skinned peas may resolve constipation-related cases. Persistent symptoms require professional diagnosis.

Quarantine new fish for at least two weeks before introducing them to established tanks. This observation period allows latent diseases to manifest while protecting your existing population. Maintain a separate quarantine tank with similar water parameters and minimal decoration for easy monitoring and medication administration.

Emerald Eye Rasbora Food And Diet

Emerald Eye Rasboras are omnivores that accept a wide variety of foods in captivity. Their natural diet consists of small insects, crustaceans, zooplankton, and algae. Replicating this variety in the aquarium promotes optimal health, coloration, and breeding condition. These fish are not picky eaters, which simplifies feeding routines while still allowing for nutritional optimization.

A quality staple diet of micro pellets or fine flake food provides essential vitamins and minerals. Supplement this base with frozen foods such as daphnia, cyclops, bloodworms, and baby brine shrimp. Live foods, including microworms, vinegar eels, and cultured daphnia, trigger breeding behavior and offer the enrichment of natural hunting behavior.

Feed small portions two to three times daily rather than one large meal. This feeding schedule mimics their natural grazing behavior and prevents the bloating that can occur with heavy single feedings. Remove uneaten food within five minutes to maintain water quality. Their small mouths require appropriately sized food; crush standard flakes if necessary for juvenile fish.

Tank Mates

Selecting appropriate tank mates for Emerald Eye Rasboras requires consideration of their small size, peaceful temperament, and preference for calmer waters. They thrive in community setups with other non-aggressive species that share similar water parameter requirements. The best companions are equally peaceful fish that will not outcompete them for food or bully them into hiding.

• Neon Tetras and Black Neon Tetras share similar size and schooling behavior
• Guppies and Platies add color without aggression
• Chili Rasboras create stunning nano schooling displays together
• Dwarf Corydoras species such as Pygmy or Habrosus Corys share the bottom level peacefully
• Small Swordtails and Rosy Barbs work in slightly larger setups
• Honey Gouramis and small Danios occupy different tank regions without conflict

Shrimp compatibility deserves special attention. Emerald Eye Rasboras are shrimp-safe and make excellent tank mates for Cherry Shrimp, Amano Shrimp, and other dwarf shrimp species. Their small mouths and non-aggressive nature mean they rarely prey on adult shrimp, though very tiny shrimplets might occasionally be eaten. The rasboras generally ignore shrimp entirely, creating a harmonious community.

Avoid aggressive or large fish that might view Emerald Eye Rasboras as food. Cichlids (except the most peaceful dwarf species), large barbs, and predatory fish like Red Devil Cichlids or Red Empress Cichlids are inappropriate companions. Fast, boisterous feeders like some tetra species may outcompete rasboras for food, leading to malnutrition over time.

Advantages Of Having Emerald Eye Rasbora In Your Tank

• Peaceful temperament makes them ideal for community tanks with other non-aggressive species
• Tight schooling behavior creates stunning visual displays unmatched by looser shoaling fish
• Compact size allows for beautiful nano tank setups in limited spaces
• Adaptable water parameter tolerances suit both blackwater biotopes and standard community tanks
• Hardy nature and moderate care requirements suit intermediate aquarists
• Active swimmers that utilize the middle and upper water column effectively
• Safe with shrimp and other delicate invertebrates
• Easy to breed for those interested in fish propagation

Disadvantages Of Having Emerald Eye Rasbora In Your Tank

• Skittish behavior requires careful tank placement away from high-traffic areas
• Need for dim lighting limits plant options and may not suit all aesthetic preferences
• Require larger schools (10+) for optimal behavior, increasing tank size requirements
• Sensitive to poor water quality and sudden parameter changes
• Slow feeding habits can lead to underfeeding when housed with faster competitors
• May become territorial within their own species if kept in groups smaller than six
• Conservation concerns exist due to palm oil industry habitat destruction in native range

Frequently Asked Questions

Conclusion

Emerald Eye Rasboras offer aquarists a unique combination of visual appeal, peaceful behavior, and manageable care requirements. Their shimmering silver bodies and striking emerald eyes create captivating focal points in planted tanks and blackwater biotopes. The tight schooling behavior they display when kept in appropriate numbers rivals more expensive or difficult species, making them excellent value for nano tank enthusiasts.

Success with these fish hinges on respecting their fundamental needs: stable water parameters, adequate school sizes of ten or more individuals, dim lighting, and peaceful tank mates. While they require more attention to water quality than some hardier community fish, the reward is a constantly active, harmonious display that brings life to the middle and upper levels of your aquarium.

Whether you are establishing your first blackwater biotope or seeking a refined addition to an existing community setup, Emerald Eye Rasboras deserve serious consideration. Their compatibility with shrimp and other peaceful species, combined with their moderate breeding potential, provides ongoing opportunities for observation and engagement. For those interested in exploring other rasbora options, our comprehensive guide to the 10 popular types of rasboras offers additional species worth considering for your next aquarium project.