The Pond itself is a community building project of sorts, that comes with four stages. The first stage is achievable by paying 10,000 coins in the game’s store, so long as you have 10 cement blocks available to turn in.
Cement Blocks can be given to you by your friends as a gift item from the game’s free gifts page, as seen below, or you can purchase them for 1 Playfish Cash each from the game’s store.
Once you have a Pond, you can upgrade it for more coins, and even more Cement Blocks (see above), an afterward, you’ll be able to purchase an Ugly Duckling to swim in it. The Ugly Duckling costs 40 Playfish Cash, and eats 30 units of Wheat at a time. It produces eggs worth 3,000 coins, and according to Playfish will apparently grow up after being properly taken care of, presumably into a beautiful swan. In addition, once you have a pond, you’ll be able to grow “special plants” within it.
Want a pond of your own in the game? Head over to the game’s page to start sending (and asking for) those Cement Blocks to (and from) your friends so that you can!