Zebrafish as a Model Organism in Research: Methods and Benefits

In vivo model organisms are popular tools for biomedicine researchers globally. They share many genes with humans, have short generation periods and are easy to maintain. For many of us, mice and monkeys come to mind when thinking about animal models. In recent decades, however, zebrafish have become a viable and more ethical alternative.

We’ll discuss zebrafish model organisms in comparison to other in vivo models below. We’ll also cover various applications of zebrafish in industries like pharmaceuticals, cosmetics, agrochemicals and ecotoxicology. 

Benefits of Zebrafish as a Model Organism

Some benefits of using zebrafish for scientific research are more obvious and practical, others are very surprising. From a practical or logistical standpoint, zebrafish:

• Can be bred very easily.
• Can be housed in large, tight knit groups.
• Produce 200-300 eggs per couple.
• Grow incredibly fast (as much in a day as a human embryo in a month).
• Are small yet robust.
• Have many organs in common with humans.

In terms of genetics and scientific viability as models, studies done in the 1990’s revealed zebrafish to contain 70% of genes found in humans; a surprising fact considering they’re not mammals. Even more impressive, zebrafish contain an 84% match with humans for disease gene homologs. This makes them extremely well suited to research involving human diseases.  But how do zebrafish compare to other popular organism models?

Why Incorporate Zebrafish into Early Drug Discovery Studies?

While mice have a distinct advantage being mammals, zebrafish possess a number of beneficial traits. Besides being more affordable and efficient, these little fish also develop externally. This means that zebrafish embryos, unlike those in mice, are fertilized outside the body.

They are also transparent. Scientists can observe and manipulate the growing fish easily. Certain tissues are also often fluorescently dyed, making them even more identifiable. Additionally, in vitro fertilization can be achieved if required. Mice on the other hand develop inside their mothers meaning these types of techniques are virtually impossible, or would come at the expense of the mother. 

Experiments need to be repeatable many times over to prove their validity. In this area, zebrafish also hold an advantage. Zebrafish reproduce about every 10 days and as mentioned above, lay hundreds of eggs. Mice lay litters of 1-10 pups 5 to10 times a year. 

The Fruit Fly (Drosophila melanogaster) is also an extremely efficient and effective model organism in disease research. Like zebrafish, they reproduce quickly and often. Still, they are not vertebrates and many of their organs operate much differently than those in humans.

Applications of Zebrafish in Research

The zebrafish genome has been fully sequenced to a level only achieved otherwise in humans and mice. Over 14,000 gene mutations have been successfully developed in zebrafish embryos.

Because of these genetic qualities zebrafish are used across a broad range of industries. 

First and foremost, zebrafish have been very successful in human disease research. Scientists are able to study mutations and identify where and when they occur as well as their further development. Typically, genetic mutations are found in human patients. These mutations are reproduced in zebrafish models organisms and observed as they develop. Pharmaceutical treatments are then tested on zebrafish to determine their viability. These trials are repeated many times over, again making zebrafish ideal due to their high reproducibility.  Advances in understanding and treatment have been made in the battle against cancer, muscular diseases and cardiovascular problems. 

The FDA’s National Center for Toxicological Research frequently uses zebrafish in ‘predictive toxicology’ research. Various drugs and substances, such as ketamine and nicotine, are tested on zebrafish to determine effects which might occur in humans. Transgenic zebrafish embryos are used to investigate the effects of copper nanoparticles on bodily systems. These particles are used in fabrics, paints and medical devices. 

In the cosmetics industry zebrafish have made a splash in multiple areas, particularly in the study of hyperpigmentation (dark patches on skin caused by excess melanin) and depigmentation agents used to treat it. Concerning agrochemicals, zebrafish have been used to detect neurotoxicity and behavioral alterations related to pesticides like the review published in 2020 where zebrafish were exposed to glyphosate and fipronil herbicides exhibited behavioral changes and negative effects on the ecosystem.  

As you can see, zebrafish model organisms prove to be an effective tools for research. They are applicable to many different industries while remaining an ethical and efficient option.