When did the first fish live on Earth – and how do scientists figure out the timing? 
By Isaac Skromne NZ Source: roanoke 7/18/2022

Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, send it to curiouskidsus@theconversation.com.

How do you figure out how long ago fish were created? Hundreds of millions of years is a long time ago. – Josh, age 11, Ephrata, Pennsylvania
 

The oldest fossils of animals resembling a fish date back between 518 million and 530 million years ago. Discovered in China and called Haikouichthys, these animals were about an inch long (2.5 cm) and had a head with seven to eight slits at its base that looked like gills. They also had a distinct spine surrounded by muscles.

 
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