Zebrafish: Science’s beloved ‘model’ organism

In the shallow freshwater ponds across South Asia lives a small fish, just about three centimetres long. With striking blue stripes on its sides, it gets the name from an animal known for stripes—the zebra. Called the zebrafish, or Danio rerio in science, it has the looks needed to make it to the aquariums. Yet, it is a favourite among a different community who look beyond its beauty— the scientific community. For good reasons, this fish is at the pinnacle of a wide range of scientific studies—from medicine to ethology.

As a ‘model organism’, scientists prefer to conduct experiments on this fish because it is readily available commercially and in the wild. It is also effortless to maintain and rear them in laboratories. With a life span of about two years, they grow into adults very fast. The fact that 70% of the zebrafish genome is similar to ours has increased this fish’s oomph in science. In the last few decades, they have forayed many scientific labs and institutes worldwide, delivering insights into many of the unanswered questions in science.

In the field of medicine, scientists are using zebrafish to understand the growth and spread of different types of cancer, conditions like obesity and diabetes, diseases of the heart, blood and other body parts, and also to learn more about the immune system. Since the zebrafish has the superpower to regenerate and repair its injured body parts, including nerve cells, scientists are trying to understand this process closer so they can replicate that in humans. Zebrafish are also used to develop many drug molecules that can treat various diseases. With its genome completely sequenced, it is even playing a vital role in understanding multiple gene functions and genetic disorders.

Recently, scientists have taken a closer look at the cognitive abilities of the zebrafish. Ethologists are studying the behaviour of wild populations to understand how they adapt to their changing environments—a constant threat to freshwater species. Recent studies from India have shown aggression among males during the breeding season, the ability to solve puzzles of finding food and how these fish alter their behaviour based on environmental changes.

With so much to offer to science, this fish truly deserves all the credits for our advancement. Be sure to think of their sacrifice the next time you see one swim in an aquarium!