How do swim bladders help fish go up and down in water?

The trick is the swim bladder, which is basically like an air-inflated balloon that can expand and contract depending on how much gas is inside. When the swim bladder expands it will increase in volume and therefore displace more water. This increases the fish's buoyancy and it will float upward.

Explanation:

the correct answer: the index of refraction of the second medium is lower i tried this persons answer and it was wrong this person is lying

b) the inside picture would look at a very high temperature in a very low ph