Ruby sundadanio

Sundadanio rubellus

Also known as Red sundadanio, Neon red rasbora

FreshwaterFish

Ruby sundadanio (Sundadanio rubellus) — The Wet Spot Tropical Fish · Used with permission

Care at a glance

Temperature: 73–81°F (23–27°C)
pH: 4.5–6.5
Adult size: 0.9 in (2.3 cm)
Minimum tank: 11 gal (40 L)
Temperament: Peaceful
Social behavior: Schooling
Swim level: Middle
Difficulty: Difficult
Breeding: Hard
Rarity: Rare
Origin: Peat swamps of southern Kalimantan, Indonesia
Family: Danionidae

Overview

The ruby sundadanio is a minute blackwater fish that needs company to feel secure, so keep a shoal of at least ten in a quiet, mature tank. It swims in the middle water and is completely peaceful, far too small to house with anything pushy; other micro species that share its soft, acidic water make the only sensible tankmates, and a species tank is safest. Feed the smallest foods, such as microworm, baby brine shrimp, and cyclops, offered often. A shaded, planted tank of around 40 liters holds a shoal, as long as the water stays soft, warm, and very clean.

In the wild

It comes from peat-swamp forest in Kalimantan, Indonesian Borneo, shallow blackwater channels and pools under deep shade, the water darkly stained, very soft, and highly acidic. Recreate that with dim light, dark substrate, leaf litter and botanicals, and gentle filtration through peat. Keep the temperature between 23 and 27 C and the pH from 4.5 to 6.5, and avoid any sudden change.

Good to know

Sundadanio rubellus, family Danionidae, matures under 2.5 centimeters. The name means reddish, and displaying males glow ember-red over a semi-transparent, blue-green body. It was described in 2011 among the species split from the old Sundadanio axelrodi. Breeding is hard: it scatters a few eggs at a time in soft, acidic water, and the tiny fry need the smallest live foods to survive.

Did you know

For years the red form of this fish was sold simply as Sundadanio axelrodi red; the 2011 revision of the genus finally gave that ruby-coloured population a name of its own.