Species description

Care, breeding and tankmates

Fish profile

Temperament

Semi-aggressive

Boraras micros is an extremely peaceful, timid, and non-aggressive schooling fish. They must be kept in a group of their own kind to help them overcome their natural shyness. While males may engage in minor, harmless display sparring, they show no real territorial behavior and will not harm tank mates.

Diet

Omnivore

In nature, Boraras micros are micropredators feeding on tiny zooplankton, insect larvae, and micro-invertebrates. In the aquarium, they require tiny food items that fit their small mouths, such as live or frozen baby brine shrimp, daphnia, microworms, and copepods. They will also accept high-quality, finely crushed flakes and micro-granules.

Life expectancy

3-5 years

Under optimal care in captivity, Boraras micros typically lives for 3 to 5 years. To maximize their lifespan, it is crucial to provide a stress-free environment, stable water parameters, and high-quality nutrition. Pristine water conditions and the absence of aggressive tank mates are key factors in helping them reach their full lifespan.

Sex ratio

Group

Boraras micros is best kept in groups rather than specific male-to-female ratios like harems. A mixed-sex group of at least 10 to 15 individuals is recommended to promote natural schooling behavior and reduce stress. In a large group, males will display more vibrant colors and engage in harmless sparring to impress females.

Feeding frequency

Twice daily

Because of their high metabolism and very small stomach capacity, Boraras micros should be fed small amounts multiple times a day. Feeding them two to three times daily is ideal to ensure they receive adequate nutrition without polluting the water. Only offer what they can consume within a minute or two.

Bioload

Low

Due to their minute size of only about 1.3 cm, Boraras micros has a very low biological footprint and produces minimal waste. A gentle filtration setup, such as a sponge filter, is sufficient to keep their habitat clean without creating strong currents. However, they are highly sensitive to spikes in ammonia, nitrite, and nitrate, meaning that a mature tank and regular water maintenance are essential.

Flow

Stagnant

This species prefers calm, slow-moving water or gentle flow, mimicking their natural swamp and wetland habitats. Strong currents can exhaust these tiny fish and cause severe stress or physical harm. A sponge filter or an air-driven filter is the ideal choice to provide adequate biological filtration with minimal flow.

Jump risk

Yes

Like many small cyprinids, Boraras micros can be skittish and may jump if startled by sudden movements, light changes, or tank maintenance. A tight-fitting lid or a mesh cover is strongly recommended to prevent them from jumping out of the aquarium. Maintaining floating plants can also help them feel secure, reducing the likelihood of startle-induced jumping.

Reproduction

Oviparous

Boraras micros is an egg-scattering species that exhibits no parental care and will readily eat its own eggs. Breeding is moderately difficult due to the tiny size of the fish and their fry. Successful spawning requires a dedicated breeding tank with soft, acidic water, dense mosses or spawning mops, and the immediate removal of adults after spawning.

Compatibility & tankmates

Due to their miniature size and shy nature, Boraras micros are only compatible with other peaceful nano-sized tank mates. They do exceptionally well with freshwater shrimp, snails, Otocinclus, and pygmy Corydoras. They should never be housed with larger or boisterous fish that could easily view them as food or intimidate them.

Tank level

Top/Middle

This species primarily occupies the middle and upper levels of the water column. They feel most secure when swimming under the cover of floating plants or tall vegetation. While they may occasionally search the bottom of the tank for food, they spend the majority of their time navigating the mid-to-top sections.