While the fish will provide enough curiosity, remember that same curiosity may tempt them to get too close to the edge to get a closer look, raising the risk of them falling in, hitting their heads on the edge of the pond, or even drown. A child can drown in less than 6inches of water.
Reduce The Slippage Factor
Just like your local pool takes preventative action (such as enforcing a no running rule), you can also take action to ensure pond safety. Consider using a slip resistant material to ensure that smooth edges around your water pond are not a hazzard. You may also want to look at creating railings along walk ways. Ask your local building authority on suggestions on how to lower the risk of someone slipping on the edge of your water garden.
During the planning stages of building your water pond, you should have contacted your municipal building authority to ensure that your plans abide by the local building codes. Do you have to build a fence around your water pond (ponds built with a certain depth require fences). How large of an area can your water garden pond be, and what other legal considerations should you make?