Dear Copper,

All living things need water. It’s how life works on Earth. But do animals that swim in water drink water?

I talked about that with my friend Nora Hickey. She’s a fish veterinarian at Washington State University.

She told me it depends on the kind of fish. Saltwater fish constantly drink water. Freshwater fish drink hardly any water.

It’s all about the salts inside their bodies. Those salts make their muscles and nervous systems work.

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