Zebrafish (IMAGE) Washington University School of Medicine Caption Zebrafish are a type of minnow widely used in scientific research and home aquariums. Small, semi-transparent freshwater fish, they reproduce rapidly and their transparent embryos develop outside the body. Such traits are helpful for viewing biological processes within the embryo or adult tissues. Credit Shu Tu Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.