How long has a clown fish been around?

The clownfish is believed to have evolved approximately 10 million years ago. Clownfish are part of the Pomacentridae family containing around 300 species of damselfish, including clownfish and anemonefish. The Pomacentridae family diversified around the time when the Isthmus of Panama formed around 3 million years ago. So while the clownfish family is an ancient one, they took the form we recognize today fairly recently.