Zebrafish

Danio rerio

The zebrafish, Danio rerio, is a small schooling fish from South Asian freshwater streams, rice fields, and slow-moving waters. It has a slim body marked by horizontal blue and silver-gold stripes, a fast feeding response, and a tolerance for a range of aquarium conditions. Zebrafish are also one of the most important vertebrate research animals because their embryos develop externally and can be observed easily.

In home aquariums, zebrafish do best in groups with open swimming space, clean water, and peaceful tankmates that can handle their speed. In laboratories, they are managed through controlled breeding, water quality systems, strain tracking, and detailed developmental records. Selective lines include longfin, golden, albino, and fluorescent varieties, but the practical needs remain those of an active schooling danio. Ethical care includes avoiding cramped tanks and maintaining genetic clarity when fish are used for research.