Gerbils are, by nature, incredibly accomplished diggers and chewers! They bore easily and there is nothing worse than seeing gerbils gnawing away at the bars of a tiny hamster cage! Gerbils do not climb as much as other rodents and so a wire cage isn't really suitable at all - they will simply not benefit from the height.
Old fish tanks are perfect for creating gerbilariums, the most creative housing for these tenacious tunnelers and the photos here show some set up with peat and hay layers before the gerbils went in (some "after" shots to come soon).