Axelrod Red Danio Care Guide - Aquarium Setup, Diet & Breeding

The Axelrod Red Danio is a minute, jewel-like danionid with a slender body and a vivid reddish to coppery sheen. Depending on mood and lighting, the flanks may show darker horizontal markings, while the fins are delicate and translucent. Its small size makes it especially appealing for carefully planned nano aquariums.

This species is active but not boisterous, spending much of its time moving through the middle and lower levels of the aquarium. In a settled group, individuals display to one another with quick, subtle movements, and their colours often intensify when they feel secure.

In the wild, Axelrod Red Danios inhabit tannin-stained waters beneath dense rainforest cover. Fallen leaves, submerged roots and low light create a sheltered environment, and the water is typically very soft and acidic. Their compact form and subdued, reflective colouring are well suited to these shaded habitats.

Sundadanio rubellus was formerly associated with the genus Rasbora and is still sometimes encountered under older common names or classifications. It is a peaceful, specialist nano fish whose small stature and preference for quiet surroundings make it quite different from the larger, more energetic danios commonly sold in the hobby.

Axelrod Red Danios are native to Borneo, particularly the blackwater peat-swamp habitats of Kalimantan, Indonesia. They come from slow-moving forest streams and shallow pools in Southeast Asia.

A group should have at least a 40-litre aquarium, with a footprint of roughly 60 by 30 cm or larger preferred over a tall, narrow tank. Use gentle filtration and subdued lighting, with dense fine-leaved plants, floating cover, driftwood and dried leaves to create shaded retreats and visual shelter. A dark sand or fine-gravel substrate complements their colours and helps recreate the forest-floor setting. Keep the water clean and stable while avoiding strong currents, exposed open spaces and sudden changes in chemistry.

Up to around 2.5 cm (1 inch) in total length. Females are generally slightly larger and deeper-bodied than males.

Feed a varied diet of suitably tiny foods, including finely powdered quality flakes or micro-pellets, small frozen foods and live foods such as baby brine shrimp, daphnia, cyclops and microworms. Their mouths are very small, so larger foods may be ignored. Offering small portions several times a day helps ensure that every fish receives enough food without leaving excess in the aquarium.

Axelrod Red Danios are best kept with other peaceful, similarly tiny species that enjoy soft, warm, slightly acidic water. Suitable companions include small Boraras species, celestial pearl danios, pygmy Corydoras and other calm micro-fish, provided the aquarium is large enough for each group. Avoid large or fast-moving danios, barbs, most cichlids, gouramis and other fish likely to outcompete, intimidate or eat them. They should also not be housed with fin-nippers or boisterous community fish.

Axelrod Red Danios are egg-scatterers that can breed in mature, soft, acidic water. Condition a group with plenty of small live or frozen foods, then provide fine-leaved plants, spawning mops or a mesh-covered base where eggs can fall out of reach of the adults. Spawning usually occurs among the plants, often in the morning. Remove the adults after spawning, and hatch the eggs in gently filtered water; the tiny fry require infusoria or another appropriately microscopic first food before progressing to newly hatched brine shrimp.

Females are usually plumper through the abdomen, particularly when carrying eggs, and may grow slightly larger. Males tend to be slimmer and can display stronger red or copper colouring, especially during courtship, although colour varies with mood, condition and lighting.