Before ever starting on a pond there is one question you must ask yourself – "Do I want to ever have fish in my pond?". There is a big difference in the way a water garden and a fish pond are built. Fish need filtration (and an adequate amount of it!) while a garden pond, depending on how clear you want your water, can have nothing other than the plants themselves. Also, more maintenance is needed for a pond if you have goldfish or koi.