While zebrafish are naturally gold with blue stripes, this specimen has been bioengineered to reflect thousands of brilliant, fluorescent colors, New Scientist reports. Nicknamed the "skinbow," this fish wasn't made because it's pretty to look at—scientists created it to better understand how skin tissue regenerates.

For their study recently published in Developmental Cell, scientists at Duke University injected a special gene into several zebrafish embryos, one of which went on to develop into a fish with multicolored skin. The gene translates into red, blue, and green fluorescent proteins, and a single skin cell from the fish contains about 100 copies of the gene. Based on all the gene combinations that are possible, any given cell could express one of around 5000 different shades. 

While the microscope the researchers used was only strong enough to make out 70 of these distinct colors, that still allowed them enough variety to track individual cells. They studied the healing process by removing a portion of the animal's fin and watching its cells regenerate. To repair the wound, neighboring cells moved in to the affected area and grew to twice their size to cover more ground. In the meantime, a fresh layer of skin cells was generated beneath the surface and rose to replace the damaged tissue in less than 30 minutes. Researchers also observed how fast skin cells naturally replaced themselves by photographing the same area of skin twice a day. It took a single cell eight days to wear off, and the entire cell sample took 20 days to cycle through completely. 

The process of tissue regeneration that's so vital to life on earth is still largely a mystery to scientists. Discovering new ways to study how it happens could help us develop better cancer-fighting medications or skin-healing treatments down the road. 

[h/t New Scientist]