Mary Moodie's Garden Centres emphasize the basic principles to bear in mind in planning your aquatic garden to ensure that you have a micro ecosystem.
Most pond plants require a sunny position to do well.
A site that collects water after rain should be avoided as this may cause flooding into the pond and muddying of the water. An even water temperature is desirable so avoid a position which is subject to cold winds particularly in spring as this will delay growth. Leaves dropping into the pond will foul the water so avoid a position with overhanging branches. The sound of running water is relaxing in the garden and can help to charge the water with oxygen, which fish breath. However, this is not essential to keep fish in a pond.