Another entry in the good-science-often-lacks-cute-animals file: ''They're not happy for a while,'' he said. ''They sort of hang out at the bottom of the tank.'' But within 10 days, the test fish were as active as their healthy schoolmates. After two months, Keating said the test fish totally regenerated their hearts, replacing all the lost tissue with new cells that vigorously pumped blood. And, most notably, there was little or no scarring.
Zebrafish have a way of fixing broken heart