My Yoyo Loaches seem to be eliminating excess gas of some kind, because I hear little noises as they get involved in eating. I don't serve beer though.

EDIT: It occurred to me that I might come across as a prude, but that isn't the case at all. I simply believe in obeying the laws that require someone be over 18 to be served beer. Not one of my tenants in my tank even approaches that age.