In many studies, zebrafish are the new lab rats

Historically, the "lab rats" scientists use to test new medicines and run studies have been, well, rats. But that may be changing. A growing number of laboratories have begun using zebrafish as their test subjects, and there is reason to believe that trend is growing.

Zebrafish, one-inch-long vertebrates, can be grown and maintained cheaply and by the thousands. Since 1988, when scientists learned to selectively mutate zebrafish DNA, the use of these tiny test subjects has skyrocketed. There were 26 academic papers featuring zebrafish in 1988, last year the number was 2,100.

By mutating zebrafish, scientists can turn the animals into models for human diseases. They are particularly useful for studies involving the cardiovascular system and certain cancers.

"The field is on fire," Leonard Zon, a researcher at Harbard Medical School, told Popular Science. Zon's lab has used zebrafish to study skin cancer, blood diseases and stem cells.

The advantages of using zebrafish over more traditional rodents make them very attractive to some labs. The fish can be grown quickly: a female zebrafish spawns hundreds of embryos at a time. They are also cheap to maintain: Popular Science calculates that a tank of zebrafish costs 6.5 cents a day to maintain, compared to 90 cents for five mice in a cage.

Additionally, larval zebrafish are transparent -- allowing researchers to observe the growth of organs as they develop.

The number of studies using zebrafish is still dwarfed by the more common rodent studies. One large advantage of using mice or rats is that many biomedical studies are better performed on mammals rather than fish. For example, any study involving lungs.