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Species profile

Black Line Rasbora

Rasbora borapetensis

Common names: Black Line Rasbora, Red Tail Rasbora, Redtail Rasbora, Red-Tailed Rasbora

Recognized speciesRasboras

Adult size

Up to 5 cm

Up to 5 cm

Countries of origin

  • See all stock from Cambodia
  • See all stock from Laos
  • See all stock from Malaysia
  • See all stock from Thailand
  • See all stock from Vietnam

Good fit for your tank?

Good fit for

  • A long tank of about 87 L or more, so a group of 10 has room to dart about
  • A community of other small, peaceful fish at 22 to 26 °C
  • A planted tank with open water in the middle where the group can school

Think carefully if

  • You only have room for three or four: a small group makes it nervous and hides its stripe
  • Your lid has gaps, because this rasbora jumps when startled
  • Your tankmates are large enough to swallow a 5 cm fish

A slim rasbora with a dark line along its side and a red tail, particularly good for beginners. Keep a group of at least 6 in 87 litres or more.

Appearance and Identification

A slim rasbora with a dark line along its side and a red tail, particularly good for beginners. It can look plain in the shop, but it colours up well once settled.

Check the scientific name when buying, as common names vary between sellers and countries.

Mature females are usually rounder in the belly, and males are usually slimmer and often brighter.

Tank Requirements

Suggested filter
About 170–260 litres an hour
Suggested heater
About 75–125 W for this tank
Minimum tank volume
87 litres
Minimum tank length
60 cm
Minimum group size
6
Recommended group size
10
Activity level
Active
Flow preference
Low
Planting preference
Moderately planted
Lid recommended
Yes
Jumping risk
Moderate

A long tank with open swimming water, plants around the edges and steady filtration suits this fish. A darker substrate and some floating plants usually bring out its colour.

Behaviour and Tankmates

Active and social, and most settled when kept with its own kind.

Keep a group of at least 6, and more if you can. Larger groups are calmer and show better colour and behaviour.

Not territorial, although males may spar and display.

Suits a community of similar-sized, peaceful fish that like the same water. Avoid large predators, which will treat it as food. It may eat baby shrimp.

Check tankmates for this species

Water Parameters

Temperature
22–26 °C
pH
6–7.5
GH
2–12
Stability importance
Important

Fairly tolerant of different water, if it is clean and stable. Keep the temperature steady.

Parameter caveat
Keep up regular water changes, and acclimatise new fish slowly.

Feeding

Diet types
Omnivore
Feeding frequency
Daily
Preferred foods
  • Small flake or micro pelletsA good staple. Feed small amounts that are eaten within a couple of minutes.
  • Frozen or live daphnia and brine shrimpOffer a few times a week for colour and condition.
  • Small bloodwormA rich treat rather than a daily food.

An omnivore that takes insects at the surface. Flake and small pellets with frozen foods suit it.

Feed small amounts, and remove anything left after a few minutes.

Breeding

Breeding type
Egg Scatterer
Breeding difficulty
Moderate
Parental care
None
Baby foods
  • InfusoriaNeeded for the first days, because most fry are very small.
  • Newly hatched brine shrimpIntroduce as soon as the fry can take it.

An egg scatterer with no parental care. Adults eat eggs and fry, so use a separate tank with fine plants, moss or mesh on the bottom, and remove the adults after spawning. The fry need very small foods at first.

Habitat and Origin

Geographic origin
Cambodia, Laos, Malaysia, Southeast Asia, Thailand, Vietnam
Natural habitat
Ditch, Pond
Aquarium contexts
Planted Aquarium
Audience level
Beginner

Classification

Profile type
Recognized species
Genus
Rasbora
Family
Danionidae
Species group
Fish, Rasboras

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