How do fish sink or float?

Answer 1

By my own understanding when a fish breathes in oxygen through the gills from the water it goes into its lungs, just like a human respiratory system.

So surely if a fish dies it will still have air inside of it. Air as we know is less dense compared with water and anything filled with air in water; tends to rise.

If the lungs are on he under side of a fish surely this would make the fish tend to roll onto its back and be 'upside-down'

Answer 2

Fish float because of an organ called a swim bladder. In fact, paleontologists (folks who study fossils) think that the modern tetrapod (four-limbed creature) lung could have evolved from a modified swim bladder.

Answer 3

If its still moving, then it's dying.

If it isn't, then it's dead.

Answer 4

some fish have air sacks that help them float cuz its full of air

Answer 5

Its oxygen rises to the top of its body in order for the fish to float upwards
All species of fish are different and prefer to dwell, or float, at different levels in the water.

Answer 6

A fish would swim vertically if it was reaching for food. If it was FLOATING vertically, I am sorry to say, but, it's most probably dead.

Answer 7

there blatter is a gas and helps it flout