if you have live rock or certain types of coral in your tank the light that is connected to your tank will creat oxygen through photosynthsis with the live rock and coral.
Yes, most freshwater fish need a air stone in their tank. And even if they don't need one it will improve the fishes health.
it cleans the tank and keep the fish heathy
Yes, every fish tank should have a filter, but depending on the kind of fish it can be exempt. If not an air bubbler is a good idea. The filter cleans the tank, along with putting oxygen in the water, and the air bubbler also puts necessary oxygen into the water.
Most of them pump air into the tank so that the fish can breathe better. You should get one if you have a bamboo shrimp, I know from expirience. The usefull thing an air pump can do is to drive a filter which is designed to remove the poisons that occur in every fish tank. Simply using it to blow bubbles is a waste.
you dont have enough O2 in your tank, you may need to buy a air stone and pump, they stay up top because there is more air in the water up there. maesure you have good circulation and lighting
no a plant does not provide oxygen in a fish tank, it has to have an air supply going to it. The fish can eat the plant though.
Betta's are a very strange type of fish. For most fish putting them into previously boiled water would kill them, boiling water removes the oxygen vital for life. However, Betta have a special organ that lets them breath atmospheric air. Which means every now and then bettas will go up to the surface to get air. So maybe there is a chance of a BETTA surviving since it would not rely on the air in the water.
fish need air because they won't be able to breath if they didn't have air, and fish need air badly because they spend most time in the water. fish need air as much as we do.
you can as long as you have a filter and a fish tank
Like all freshwater fish, It depends on the power of the filter and how clean the water is...
Cause its dead
You could as long as they are tiny, but they need a better tank than that, they need filtration and air in the water, very few fish can live in a bowl for very long, the ammonia builds up or the air runs out.