Model organism
A species studied in depth in laboratories to answer general questions in biology, such as the zebrafish and medaka.
Also: laboratory fish, research fish
Some fish are used as model organisms because they are small, breed fast and are easy to keep. The zebrafish, a minnow from South Asian rivers including the Ganges basin, has see-through embryos that grow outside the mother, so scientists can watch organs form cell by cell; it is used to study development, disease and the effects of drugs. The Japanese medaka, the three-spined stickleback, the Mexican tetra and the short-lived turquoise killifish are other models. Fish research has also shaped the study of evolution, hearing and electricity.