Take a tour of the Johns Hopkins Zebrafish Facility with some of the researchers that use these fish as a model organism in their research.
There are many advantages to using zebrafish. While it may not seem like it at first, there are many physiological characteristics humans share with zebrafish. These little fish are also transparent in their early days of development, making it very easy to simply see inside of them as their organs are growing. That process also happens relatively rapidly; they grow from birth to early adulthood in about three months.
You can hear more about the studies that are proceeding at Hopkins using zebrafish from the video.