my newest tank is a 20 gallon with a sand substrate, which some of you may have read has 2 juvenile african leaf fish, a rubber lipped plecos, a striped peacock eel, and a rapheal catfish. i havent had a problem with lack of oxygen, but i decided to hook up the bubblewand (its "glued" to the bottom, not literally glued, i just cant remember what the stuffs called ) its hidden under the sand. when i plugged it in. the fish seemed fine, just a little nervous. im wondering if these kinds of fish really need the extra oxygen or what? thanks in advance for any help or opinions