Marginal plants will help with frogs and toads as protective cover. Do you plan to have any "natural" edge on your pond. Amphibians do best in fish-free bodies of water, but they will show up and make a home either way. Having a shallow fish-free body of water (wetland) near your pond is great for wildlife, especially amphibians, even if it only holds water part of the year. Post pictures if you can.