A boy was terribly ill. His legs and belly were swelling, and his lungs kept filling with fluid. He was going to die. Born with a rare, complex genetic condition, he owes his life to creative medicine and zebra fish the go-to lab animal in countless studies of genetics, development, and disease. Dr. Hakon Hakonarson, a pediatric lung specialist and director of the Center for Applied Genomics at Children’s Hospital of Philadelphia (CHOP)Hakonarson and his colleagues identified the mutation causing the boy’s illness resulting in lymphatic vessels proliferate out of control and leak fluid into the lungs and other organs. They engineered this mutation into zebrafish and waited for the fish to develop a similar version of the boy’s disease. Then they tested multiple drugs on the fish until they found one that stopped the vessels’ kudzu-like growth. and got permission from federal health officials to try it on their young patient. The drugs worked and the boy is on his way to good health and long life.