Fish

📖 In short

Fish are animals that live in water, in seas, rivers and lakes. They have a backbone, breathe with gills and swim with fins. There are more kinds of fish than all the other kinds of vertebrates put together!

🤩 Did you know?

The first fish appeared about 500 million years ago.
The sturgeon is one of the biggest freshwater fish; one weighed about 1500 kilograms.
The whale shark is the biggest fish in the world.
Most fish lay huge numbers of eggs, sometimes millions.

🔎 Find out more

🌟 How do they breathe underwater?

A fish gulps water through its mouth, and it flows over the gills on each side of its head. The gills take the oxygen dissolved in the water, then the water flows out through the gill slits.

🔍 Fins and tail

A fish swims by swishing its tail from side to side, and uses its other fins to steer, stop and balance, like a bike's handlebars and brakes.

💡 Protective scales

Most fish are covered in small scales packed together like roof tiles, and a slimy coating that helps them slip through the water and protects them from disease.

🎯 Amazing fish

There are fish that fly above the water, fish that glow in the dark depths of the sea, fish that puff up like a spiky ball, and fish that walk on their fins in the mud!