: For Koi, a depth of at least 3 feet (approx. 1 meter) is recommended to ensure they have room to grow and hide from predators. Structural "Posts" & Shelves

: Digging a ledge approximately 1 foot deep and 12–18 inches wide around the perimeter allows for marginal plants like Iris or Pickerel .

True "deep water" plants can survive with 4 to 10 inches (or more) of water over their crowns.