How Do Fish Breathe Underwater? | Easy Science Reading

This short science reading passage is for English learners. Read the passage, learn key vocabulary, and answer the questions.

Fish use gills to take oxygen from water.

Reading Level

A2-B1

Word Count

285 words

Reading Passage

Fish live in water, but they still need oxygen to survive. People get oxygen from air with lungs. Fish get oxygen from water with gills.

Water has a small amount of oxygen mixed inside it. This oxygen is not the same as the oxygen in an air bubble. It is dissolved in the water, so fish need special body parts to take it out.

Most fish breathe by opening their mouths and taking in water. The water moves over the gills. Gills are thin and full of tiny blood vessels. These small blood vessels help oxygen move from the water into the fish's blood.

At the same time, carbon dioxide leaves the fish's blood and goes back into the water. This exchange helps the fish keep living, moving, and growing.

After water passes over the gills, it flows out through openings near the sides of the fish's head. This movement is very important. If water does not move over the gills, many fish cannot get enough oxygen.

Some fish must keep swimming so water keeps moving over their gills. Other fish can pump water over their gills while staying still. Different fish use slightly different methods, but the main idea is the same.

Fish do not breathe water itself. They take oxygen from water. Their gills are built for this underwater job.

Fish breathing shows how animals are adapted to their homes. A fish's body is made for life in water.

Water moves over gills so oxygen can enter a fish's blood.

Key Vocabulary

Word	Meaning	Example
gills	body parts that help fish take oxygen from water	Fish use gills to breathe underwater.
oxygen	a gas that animals need to live	Fish take oxygen from water.
dissolved	mixed into a liquid	Oxygen is dissolved in water.
blood vessels	tiny tubes that carry blood	Gills have many blood vessels.
adapted	changed or built for a certain way of life	Fish are adapted to live underwater.

Reading Comprehension Questions

1. What do fish use to breathe underwater?
2. Where is oxygen found in water?
3. What happens when water moves over the gills?
4. What leaves the fish's blood?
5. Why must water move over the gills?

Answers

1. Fish use gills to breathe underwater.
2. Oxygen is dissolved in the water.
3. Oxygen moves from the water into the fish's blood.
4. Carbon dioxide leaves the fish's blood.
5. Water must move over the gills so fish can get enough oxygen.

Short Summary

Fish breathe underwater with gills. Water moves over the gills, oxygen enters the blood, and carbon dioxide leaves the body.

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