Getting the air out is easy, just thread an air-tube and suck it out. It's amazing how much air the average humans lungs can hold. 
I used that with a little fish diving-bell I was playing around with in a 10 gallon. I also want to make a bridge from plexiglass. (Click for bigger images)

I used some floating pellets to lure the fish up there. The molly learned quick.. would swim up into it whenever I walked by.
Finally going to get him some friends. Tank has cycled (and been upgraded to a 20 long) and I plan on adding some females and Bio-Spira tomorrow.

I used that with a little fish diving-bell I was playing around with in a 10 gallon. I also want to make a bridge from plexiglass. (Click for bigger images)



I used some floating pellets to lure the fish up there. The molly learned quick.. would swim up into it whenever I walked by.

Finally going to get him some friends. Tank has cycled (and been upgraded to a 20 long) and I plan on adding some females and Bio-Spira tomorrow.