No matter what size you plan your
pond to be, you will always wish you had made it larger.
A pond 100 sq ft of surface area or larger provides
an ideal amount of surface area for many varieties of
aquatic plants and fish. This is not to say however
that a smaller pond or a container garden cannot be
enjoyable or interesting. The minimum depth should be
18 inches for ponds with plants and ornamental fish
that are not Koi. However, if you are in a colder climate
or are keeping only Koi your depths should be 3 ft or
deeper. The proper depth will enable fish to survive
the winter more easily and keep them cool in the summer
months. A shelf of 12-18 inches wide and about 9-12
inches below the surface can be created for the placement
of marginal plants and some other potted aquatic plants.