Species description

Care, breeding and tankmates

Fish profile

Temperament

Peaceful

The Emerald Dwarf Rasbora is completely peaceful toward other species but can be highly timid and easily stressed. Within their own species, males are quite combative, constantly engaging in harmless, flared-fin sparring matches to establish dominance. Providing a large enough group and dense planting is key to making them feel bold enough to display.

Diet

Omnivore

In their natural habitat, they feed on micro-invertebrates and zooplankton. In captivity, they require very small foods such as crushed high-quality flakes, micro-pellets, and finely powdered fry food. Live foods like microworms, newly hatched brine shrimp, and daphnia are highly recommended to encourage them to forage.

Sex ratio

Group

Males are noticeably more colorful, displaying bright emerald bars and reddish-orange fins, while females are duller and plumper. Males will constantly spar and display to one another, so keeping a higher ratio of females to males helps distribute this aggression. A group of at least 8-10 individuals is highly recommended.

Feeding frequency

Twice daily

Due to their small stomachs and fast metabolism, they should be fed tiny amounts of food twice a day. They are timid feeders that will carefully inspect food before consuming it, often preferring items slowly sinking through the water column. Ensure that food reaches their hiding spots if they are reluctant to come out.

Bioload

Low

The Emerald Dwarf Rasbora is a very small fish that produces a minimal bioload, making it ideal for nano aquariums. Even a sizable group will have a negligible impact on a well-cycled tank's filtration system. However, their sensitivity to poor water quality means regular small water changes are still mandatory.

Flow

Strong

They originate from Lake Inle in Myanmar, which has relatively still, calm waters densely packed with vegetation. They prefer low to moderate flow in the aquarium, as strong currents will quickly exhaust these small fish. Gentle filtration from a sponge filter or a baffled hang-on-back filter is ideal.

Jump risk

No

Reproduction

Oviparous

They are egg scatterers that are relatively easy to breed in a dedicated, densely planted breeding tank. Females will deposit a few adhesive eggs daily among fine-leaved plants like Java moss. The parents will eat the eggs and fry, so adult fish should be removed after a few days of spawning.

Compatibility & tankmates

Peaceful

They are incredibly peaceful but exceptionally shy, making them suitable only for species-only setups or tanks with other timid nano fish. Larger or overly active tank mates will outcompete them for food and force them into constant hiding. Excellent companions include Boraras species, pygmy corydoras, and Neocaridina shrimp.

Tank level

Middle

They are reclusive fish that primarily occupy the middle and lower levels of the aquarium, rarely venturing to the very top. They strongly prefer densely planted tanks where they can weave in and out of the vegetation. Without abundant hiding places, they will remain stressed and pale.