Black Line Rasbora (Rasbora borapetensis) Species Profile & Care Guide

The Blackline Rasbora is a robust, hardy, peaceful fish which can be housed with other temperate species. These fish are relatively widespread and prefer slow-moving water and a heavily planted aquarium.

This species of Rasbora is a true schooling fish and can always be seen in a tight school, darting back and forth in the middle and upper regions of an aquarium.

The Blackline Rasbora is streamlined, silver in colour and sports a dark brown to black, mid-lateral stripe leading from the gill opening to the front of the caudal fin base. Above that line is a gold bar and the caudal fin is a bright red colour.

Natural Habitat of the Black Line Rasbora

You can find Blackline Rasboras in the great Mekong and Chao Phraya River, as well as the Mae Klong in western Thailand. They have also been reported in Cambodia, Laos, Vietnam, Peninsular Malaysia and China.

Its population extends further into the Philippines and the Sunda Islands including parts of Malaysia, Indonesia, Brunei Darussalam and Singapore in Southeast Asia.

They inhabit shallow slow-flowing almost still thickly-vegetated turbid waters in ditches, ponds, drains, canals, streams, swamps and reservoir margins.

Other Rasboras of interest

Diet

In captivity, these fish will readily accept dried, suitably sized foods such as flakes, granules, and pellets. Keep these as the staple of their diet but make sure you also provide them with daily meals of small live or frozen food such as artemia, tubifex, bloodworms, mosquito larvae and daphnia. This will help the fish to maintain good health, growth and colour and will also help to induce spawning.

Sexing the Black Line Rasbora

It is quite tricky to differentiate males from females as they look very similar. However, the females are slightly fatter, broader, and deeper bodied, and have a whitish belly, whereas the males are more slender and smaller, with a creamy-yellow or reddish belly.

Breeding the Black Line Rasbora

Like many Rasboras, the Blackline Rasbora is a continuous egg scattering, spawner that presents no parental care. These fish vary slightly in their spawning method. Rather than being open water egg scatterers, their eggs are scattered among the leaves of plants.

Condition them with small contributions of live foods several times a day, for around four weeks. This will bring out the best colour in males and induce spawning.

A large tank will be required for spawning because part of the courting is a very intense pursuit. The female will hide until she is ready to produce.

The water should be slightly harder than the average water condition, you should slightly decrease the acidity, and you should slightly raise the temperature. Filtration isn't required, but if you like, you can add a small, air-powered sponge filter or some peat filtration.

Spawning will usually occur in the early hours of the morning where they take up a side by side position with the male embracing the female. The female will then scatter the eggs amongst the leaves of plants. After her first drop, the female will then go and find another hiding area until the next spawn.

Once the couple has finished spawning, you will need to remove them from the tank to avoid the eggs being consumed.

The fry will hatch 3 to 4 days after they have been laid, and they become free-swimming around three days after that.

It would be best to feed the fry with infusoria, Paramecium or powdered foods for the first few days. The fry quickly grows and will soon be large enough to eat baby brine shrimp.

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