What fish need oxygen in water?

No fish likes to be in bad water although there are some species that have developed methods of surviving in these bad low Oxygen conditions. The Anabantid family which includes the Betta and the Gouramies have developed a "Labyrinth" which allows them to get oxygen from the air by means of a chamber in their skull are some that can survive in poor water conditions. You should still follow the basic rules of fish keeping if you want to be successfull keeping fish. The rules are. :-1 inch of fish needs at least 1 gallon of water. :- Every tank needs a permanently running cycled filter. :- Every tank needs at least 50% of its water changed every week. If you keep to the above rules, and feed the fish good food it/they will stand a chance of living a normal lifespan. If you fail in any of them I can guarantee that your fish will be constantly getting sick and will have a very short lifespan.