Zebra Danio

Scientific name: Danio rerio, listed by some as Brachydanio rerio

Adult size: up to 5 cm

Origin: Ganges basin, northern India and Bangladesh

Water: 18–25 °C, pH 6.0–8.0, 5–20 dGH

Group: 8–10 or more

Diet: micropredator, accepts almost any food

Temperament: very peaceful, fast and active

The zebra danio is a slim silver fish with five horizontal blue stripes running the length of the body, reaching up to 5 cm. It was described from the Kosi River in the Ganges system and is native to northern India and Bangladesh, where it lives in slow streams, ponds and flooded rice paddies. It is among the hardiest aquarium fish and tolerates a wider temperature range than most tropicals, comfortable down to 18 °C, which is why it is often kept in unheated indoor tanks in mild climates. It is active to the point of restless and never stops moving, so it wants swimming length rather than height and is not a good match for slow, timid fish that dislike constant traffic. Keep a group of eight to ten or more to spread that energy around; in smaller numbers individuals can become nippy. It is a micropredator that feeds on small crustaceans and insects in the wild, but it will accept just about anything offered in the aquarium.

Water: 18–25 °C and pH 6.0–8.0, hardness 5–20 dGH. It is forgiving of a range of conditions but still needs a cycled tank and regular partial water changes; it prefers a bit of flow and well-oxygenated water.

Tank and planting: a long tank with open swimming space along the front, plants around the sides and back, and a tight-fitting lid, because danios jump.

Feeding: quality flake or granules as the staple, plus frozen or live daphnia, brine shrimp and bloodworm. It feeds greedily at all levels, so make sure slower tankmates still get their share.