Where do fish breathe?

Here's how it works:

* Water enters the mouth: Fish open their mouths and take in water.

* Water flows over the gills: The water then passes over their gills, which are delicate, feathery structures located on either side of their head.

* Oxygen is absorbed: The gills contain tiny blood vessels called capillaries. As water flows over the gills, oxygen from the water diffuses into the capillaries.

* Carbon dioxide is released: At the same time, carbon dioxide from the fish's blood diffuses out into the water.

* Water exits the gills: The water, now depleted of oxygen and enriched with carbon dioxide, exits the gills and flows out of the fish's body.

So, while fish live in water, they don't breathe the water itself. They use their gills to extract oxygen from the water and release carbon dioxide.