Greater scissortail - Rasbora caudimaculata

Scientific name: Rasbora caudimaculata

Common name: Greater scissortail

Family: Cyprinidae

Usual size in fish tanks: 14 - 17 cm (5.51 - 6.69 inch)

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Recommended pH range: 6 - 7

Recommended water hardness: 2 - 12°N (35.71 - 214.29ppm)

0°C 32°F30°C 86°F

Recommended temperature range: 20 - 26 °C (68 - 78.8°F)

The way how these fish reproduce: Spawning

Where the species comes from: Southeast Asia

Temperament to its own species: peaceful

Temperament toward other fish species: peaceful

Usual place in the tank: Middle levels

General Information

The Greater Scissortail (Rasbora caudimaculata) is a sizable rasbora native to Southeast Asia, with confirmed populations on the Malay Peninsula, Sumatra, and Borneo. It inhabits clear to tannin-stained forest streams and larger rivers, moving actively in midwater. Adults commonly reach 14–17 cm, making this a much larger rasbora than typical “nano” species. Distinguish it from the smaller, more familiar R. trilineata by the orange-red marks at the base of each caudal lobe ahead of the black tips.

Food & Feeding

Omnivorous and unfussy. Use quality flakes or sinking granules as the staple and rotate frozen/live items (daphnia, brine shrimp, mysis, finely chopped bloodworms) several times per week. Offer modest portions 1–2× daily to protect water quality.

Sexing

Males are slimmer and typically show a yellowish wash in the anal fin; females are deeper-bodied, especially when gravid. Compare adults side-by-side for best accuracy.

Breeding

Reportedly an egg-scattering free spawner in nature; reliable aquarium spawnings are not documented. If attempted, use a large, dim tank with very soft, slightly acidic water, fine plants/spawning mops or marbles, and remove adults post-spawn as with other rasboras.

Lifespan

With space, clean water and a varied diet, expect around 8–10 years in captivity (longer is possible). (Hobby consensus; large, slow-maturing rasboras tend to be long-lived.)

Tank Requirements & Water Parameters

Tank size: this is a powerful swimmer—use a long tank of at least 150 cm/5′ length for a shoal; larger is strongly recommended. Provide open lanes.
Water: keep very clean, well-oxygenated water with moderate flow. Target pH ~6.0–7.0, hardness from soft to mid (~2–12 °dH), temperature 20–26 °C. Stable parameters matter more than chasing exact numbers.
Aquascape: sand or fine gravel, rounded stones/wood, robust planting (edges/back), and a tight-fitting lid—they are excellent jumpers.
Maintenance: weekly water changes; avoid abrupt parameter swings.

Compatibility & Tank Mates

Peaceful, energetic shoaler. Keep in groups of 6–8 to diffuse dominance and see natural schooling. Combine with similarly robust, mid-sized fishes (larger rasboras/tetras, peaceful barbs/rainbows, sturdy catfishes). Avoid tiny fry-sized tank mates.

Behaviour & Usual Place in the Tank

Occupies the middle (to upper) water column, cruising open water and diving into cover when startled. Provide long, unobstructed swimming runs and shaded retreats.

Short Description

Greater Scissortails are large Southeast Asian rasboras famed for their red-tipped, scissor-like tails and constant midwater activity. They require a spacious, well-filtered, well-oxygenated setup, a varied omnivorous diet, and a proper shoal for best behaviour and colour.

Q&A

Where are they from? Southern Malay Peninsula plus Sumatra and Borneo; forest streams to larger rivers, clear through blackwater.
How do I tell males from females? Males are slimmer with a yellowish anal fin; females are rounder.
Are they plant-safe? Yes; not plant-eaters, though big adults may gulp very tiny fish.
Do they jump? Absolutely—use a tight-fitting cover.