The Zebra Danio or Zebrafish (Brachydanio rerio or Danio rerio) is a tropical fish belonging to the minnow family (Cyprinidae). Originating in Eastern India, it grows to about 2 inches (6 cm) and lives for around 5 years. There are long-finned and other color forms of this danio.

The Zebra Danio or Zebrafish (Brachydanio rerio or Danio rerio) is a tropical fish belonging to the minnow family (Cyprinidae). Originating in Eastern India, it grows to about 2 inches (6 cm) and lives for around 5 years. There are long-finned and other color forms of this danio.

Like other danios it is omnivorous and a peaceful fish that gets along well with other fish in community tanks. A schooling fish, it prefers to be in groups of 6 or more. Zebra Danios prefer water with a 6.0–8.0 pH, a water hardness of up to 5.0–19.0 dGH, and a temperature range of 64–74°F (18–24°C).

Males have gold stripes between the blue stripes and females have silver stripes instead of gold. An egg-scatterer, danios produce around 100 eggs in a single spawning.

Zebra Danios serve as a common and useful model organism for studies of vertebrate development, because it reproduces very easily, passing from the egg to the larvae stage in less than three days. For genetic research groups, the Zebrafish is an excellent test subject and has already replaced rats and mice in many labs.

Zebra Danio are susceptible to Oodinium, or Velvet disease.