Blue Danio Care Guide - Aquarium Setup, Diet & Breeding

The Blue Danio, Danio kerri, is a small, lively cyprinid with a slender body and an attractive blue-green to turquoise sheen. Depending on lighting and locality, the body may show a deeper blue lateral stripe, while the fins are generally transparent with subtle yellowish or amber tones.

These active fish spend much of their time in the middle and upper levels of the aquarium, darting through open water and investigating their surroundings. They are peaceful but energetic, and their constant movement is most natural when they are kept in a social group.

In the wild, Blue Danios are associated with shallow streams and pools in southern Thailand. Their streamlined shape and active swimming style reflect life in well-oxygenated waters, where they feed among vegetation, submerged roots and the edges of gentle currents.

Blue Danios are sometimes sold under the name Turquoise Danio. They are closely related to other small Danio species, but their shimmering blue coloration and manageable adult size make them a particularly appealing choice for a planted community aquarium.

Blue Danios are native to southern Thailand, including the Phuket and Ko Yao island areas in the Andaman Sea region of Southeast Asia. They inhabit clear, shallow freshwater streams and other gently flowing waters.

A group of Blue Danios should have at least a 60-litre aquarium, with a footprint of around 60 × 30 cm or larger to provide uninterrupted swimming space. Use a secure lid because these active fish can jump, and combine open areas with hardy plants, driftwood and smooth stones around the edges. A dark, fine-grained substrate can enhance their blue coloration, while gentle water movement and good oxygenation suit their stream origins without creating an excessively strong current.

Blue Danios reach about 4.5 cm (1.8 in) in maximum adult length. Females are usually slightly deeper-bodied and may grow marginally larger than males.

Blue Danios are omnivores and should receive a varied diet of quality small flakes, micro pellets and granules. Supplement these with small live or frozen foods such as daphnia, baby brine shrimp, mosquito larvae and cyclops. Their small mouths suit finely sized foods, and occasional vegetable-based ingredients can form part of a balanced diet.

Blue Danios suit peaceful community aquariums and can be kept with other active but non-aggressive species such as small rasboras, ember or black neon tetras, white cloud mountain minnows, peaceful Corydoras and smaller peaceful loaches. Avoid slow, long-finned fish that may be stressed by their activity, as well as fin-nippers, large predatory fish and aggressive species. Keeping an appropriately sized group helps prevent them from bothering tankmates.

Blue Danios are egg-scattering spawners that can breed readily in a mature aquarium. Condition a group with plenty of live or frozen foods, then move the adults to a separate breeding tank with gentle filtration and a layer of spawning mops, fine-leaved plants or marbles to protect the eggs. Spawning usually takes place in the morning, after which the adults should be removed because they may eat the eggs. The eggs hatch in roughly 24–48 hours, and the free-swimming fry can be raised on infusoria or a suitable liquid fry food before progressing to newly hatched brine shrimp.

Males are generally slimmer and more streamlined, with a stronger golden or yellowish tone in the body and fins. Females tend to be fuller through the abdomen, especially when carrying eggs, and often appear slightly larger and less intensely coloured.