Because they need it. They can't actually breathe out of water so they need things like filters or the back of boats to make air bubbles
Fish breath underwater
they have gills.
I will assume you are not joking. A fish does not hold it's breath it can breathe underwater using its gills.
Um, with gills. . . ??
they have gills
Because you have lungs and fish have gills.
Yes there is air underwater. Water is a mix of Hydrogen (H) and Oxygen (O). Hence the name 'H2O'. Hope I helped. (also, fish filter the oxygen through their gills to breath.)
yes penguins do need air to breath underwater.
They have gills which enable them to breath underwater.
w
Tortoise does not have gills to help it breath underwater.
Seahorses are fish that live underwater and breath with gills, and have fins.