Dr. Universe: How can you tell if a fish is female or male? Or if it is a kid or adult or teenager? -Hanaiah, 7, Zhujiang New Town, China
rcwebberDear Hanaiah,
There are more than 34,000 species of fish on our planet. It can be tricky to tell the age or sex of a fish, but biologists have come up with a few different ways to find out.
My friend Paul Wheeler, a fish biologist at Washington State University, told me all about it.
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