Fish rule the world. That is, they’re one of the oldest animal families to live on Earth. They were here long before the dinosaurs – about 500 million years ago — and they still thrive. There are over 25,000 known species of fish. There are probably many more that we haven’t discovered yet.
Fish are vertebrates. That means they have a backbone. But unlike mammals, fish don’t have lungs. They breathe by taking oxygen from the water in through their mouths, where it passes over the gills. The gills then absorb oxygen from the water and send the oxygen throughout the body. Some fish are carnivores. They eat other fish and small animals and insects. Other fish are omnivores, eating both plants and animals.
Fun Facts About Fish for Kids
- Fish are cold-blooded like reptiles and amphibians. They can’t control their body temperature.
- Some fish live in salt water, such as halibut and cod. They live in oceans and seas. Freshwater fish, such as trout and catfish, live in lakes and rivers.
- Salmon migrate every year to breed and lay eggs.
- Fish have a good sense of taste, sight and touch. They can feel pain.
- The largest fish is the great whale shark. It can grow to 50 feet long. The tiny Philippine goby is about the size of your pinky fingernail.
- Thrive: grow and live well
- Vertebrate: an animal with a backbone
- Cold-blooded: unable to regulate body temperature
- Migrate: temporarily move
Learn More All About Fish And Their Major Types
Watch an intriguing video about how the seahorses got their body shape:
A video documentary about the anatomy of a seahorse.
Question: Are sea horses fish?
Answer: Despite their horsey shape, sea horses are fish. They have very small fins and can’t swim fast.
Question: Do people ever farm fish?
Answer: People farm, or raise, fish in the ocean, as well as on land. Large man-made pools or tanks are called hatcheries. Fish are born and raised here to sell as food.