Re: aqua babies?
Correct, Psycho, but only biological filtration. Yes, fishboy, it does provide biological filtration, but then again, so does the gravel, the tank walls, the plant, etc.; anywhere where the nitrifying bacteria can grow. It doesn't, however, provide mechanical or chemical filtration.
Ryan, an "aquababy" is a teeny tiny acrylic cube (about 1.5 pints, I think) that houses 1 live fish or frog, a teeny plant, "live" gravel, and water. The fish are usually fry. The ones I've seen had zebra danios in them, and when the fish grows at all there simply won't be enough room for him.
In short, they're torture chambers for fish. Thankfully, I haven't seen any down here since I moved here.