In order to better understand human diseases, scientists often study smaller and less complex animals. Ideally, these model organisms grow and reproduce quickly, and produce many offspring. This is important because you need a large amount of data to form good conclusions. The zebrafish is one such commonly used model organism.

The scientific name for the common zebrafish is Danio rerio. These tropical freshwater fish can grow to be 1 to 2 inches long and are native to countries in South Asia, like India and Bangladesh. Zebrafish eat small living organisms like shrimp and insects, and are themselves eaten by larger fish, amphibians, and birds.  Zebrafish are commonly kept as pets and can thrive in a home aquarium. These fish share many traits with humans, so they are often used in scientific research. Like all living things, these fish contain DNA which contain the instructions for producing all the proteins that make up a fish. Proteins are the key building blocks of all living organisms. The regions of DNA that encode the information for making a protein are called “genes,” and scientists have found that the genes of zebrafish are very similar to human genes. For example, zebrafish and humans have similar cellular structures for the eyes, heart, liver, nervous system, and skin pigmentation.

Studying embryo development in zebrafish is fairly easy for two reasons. One, larval zebrafish are transparent. Two, the young fish develop in a simple dish. Scientists have successfully used the zebrafish as a model to better understand embryology, organ regeneration, and stem cell biology.