Fish - The Most Popular Species in the Water Animal Water

There are many types of animal in this world. 

Some of them can be found on the land, like cows, horses, cats, dogs, monkeys and many others. 

Some are seen flying on the air, like birds and flying insects. 

The last and the largest habitat of the animals is the water. 

There are many different animals that you can find in the water. 

The most popular one is fish.

Exploring the water animal world is very fantastic. 

You can find various types of fish species. 

There are small fish and big fish. 

The shapes also can be various. 

If you dive to the deep sea, you will meet the colorful fish with various shapes and sizes. 

Just like any other animal species, fish also needs oxygen. 

Fish have gills on the both sides of the head. 

The function of the gills is to filter the oxygen from the water. 

With this magic organ, fish can stay alive under the water.

There are freshwater fish and marine fish. 

The freshwater fish can be found at the river or lake. 

This type of fish is only able to live in the water with low salinity level. 

It is different with the marine fish that needs the salty water to stay alive.