oxygen pump

also white clouds, and there are a couple species of snail and other things... check out aquariumfish.net it will tell you anything and everything you could ever want (or not) to know about pet fish. hope this helps

Goldfish is incorrect, they need a filter in their tank. The only fishes I can think of off hand are bettas and gouramis. They're both labrynth fish-meaning they take oxygen from the surface of the water, as opposed to other fish that take the oxygen in through the water. Interesting, this site also includes perch in that group, didn't know that! Lists a few other species as well-snakeheads and some eels: http://www.labyrinthfish.info/lf/index.cfm .

goldfish and betta's

Corydoras catfish and a few other fish will take gulps of air at the surface and the oxygen will be extracted in their intestines. The bubbles provided by an air stone do not add any oxygen to the water but rather just help to circulate the water so that carbon dioxide and other harmful gases can escape into the air and oxygen and can be replenished in the water.

I only know about Betas. They don't need any kind of oxygen pump. My sister-in-law had hers in a little glass bowl on a special shelf and it lived fine. You just need to remember not to put more than 1 male Beta in the tank. They can be with other fish that are not fin-nippers. They usually get along with most other fish. I had mine in with goldfish,mollies and guppies.