FaunaHub

Zebrafish (Danio rerio)

FishFreshwaterModel Organism

Zebrafish (Danio rerio) swimming, showing the horizontal blue-silver stripes along the body.

Zebrafish (Danio rerio); the horizontal stripes give the species its name.

Image: Pogrebnoj-Alexandroff, CC BY-SA 3.0, via Wikimedia Commons.

Overview

The zebrafish (Danio rerio) is a small freshwater cyprinid from South Asia, marked with horizontal blue-silver stripes running the length of the body — the pattern that gives it its name.

In the wild it is an unremarkable little shoaling fish of slow, shallow water. Its significance lies elsewhere: the zebrafish is one of the most important model organisms in biology, alongside the fruit fly, the mouse and the nematode worm.

Two properties made that possible. Zebrafish embryos develop outside the mother and are transparent, so organ formation can be watched directly under a microscope, and the fish has a remarkable capacity to regenerate tissue including fins, spinal cord and heart muscle.

Habitat & Range

Zebrafish are native to South Asia — the Ganges and Brahmaputra basins across India, Bangladesh, Nepal and neighbouring areas. They live in shallow, slow-moving or still fresh water: streams, canals, ponds, ditches and seasonally flooded rice paddies, typically with silty bottoms and some vegetation, and they tolerate a wide range of temperature and water conditions.

Diet

Zebrafish are omnivores, feeding mainly on small invertebrates — zooplankton, insects and insect larvae, especially mosquito larvae — along with algae and organic detritus. They feed throughout the water column and are opportunistic, which is one reason they are straightforward to maintain in laboratories.

Behavior

Zebrafish are shoaling fish, and their strong preference for company has itself become a subject of behavioural research. They spawn readily, scattering eggs over the substrate at dawn with no parental care, and produce large numbers of embryos frequently — a major practical reason for their adoption as a research animal. In the wild they are active by day and are prey for larger fish and birds.

Human Interaction & Conservation

The zebrafish is central to modern developmental biology, genetics, toxicology and disease modelling. Because its embryos are transparent and develop externally, researchers can watch organs form in a living animal, and its regenerative abilities are studied for what they might reveal about repair in animals that lack them. Zebrafish are also kept in home aquaria, where several ornamental varieties exist. This profile is educational and offers no aquarium husbandry advice. In the wild the species remains widespread; verify current status at the IUCN Red List.

Frequently Asked Questions — Zebrafish

Why is the zebrafish so important in research?
Because of how easy it is to observe and work with. Its embryos develop outside the mother and are transparent, so organ formation can be watched directly in a living animal; it breeds readily and produces many embryos; it is a vertebrate, so findings are more transferable to humans than those from insects; and it regenerates tissue that mammals cannot.
Can zebrafish regenerate body parts?
Yes, to a striking degree. Zebrafish can regenerate fins, parts of the spinal cord, retinal tissue and heart muscle — capacities that mammals largely lack. This is a major reason the species is studied in regenerative medicine research.
Where do zebrafish come from?
South Asia — the Ganges and Brahmaputra river basins across India, Bangladesh, Nepal and neighbouring areas. They live in shallow, slow or still fresh water such as streams, canals, ponds, ditches and seasonally flooded rice paddies.
What do zebrafish eat?
They are omnivores. In the wild they take small invertebrates — zooplankton, insects and insect larvae, including mosquito larvae — along with algae and organic detritus, feeding opportunistically through the water column.

Sources and further reading

Authoritative wildlife references used for general educational context. Conservation status should always be verified against current IUCN Red List data. External links open in a new tab.