Airfoil for silent-running ventilation

I'm looking for small fans for use in a terrarium/vivarium (about 30 gallons or so), but want it to be silent (or very near). It doesn't need to be an airfoil design, but that's what came to mind when thinking silent. My hope is that one blowing air in at one end of the cage and another blowing out at the other end will work out. I know vibration reduction plays a factor, but there's also the sound of the motor and buffeting. Any advice concerning vibration reduction would be nice, but I would like to start with a fairly silent fan - so product recommendations?