Here is some advice from the Suffolk Wildlife Trust
Golden rules for pond planting
Avoid inadvertently introducing alien, invasive species which out-compete our native pond plants and pose a threat to our native invertebrates, amphibians and fish by blocking out heat and light from the water. These are sometimes sold as oxygenating plants in garden centres, or, fragments of them may have got into pots of other plants (some stores only stock native only plants to reduce this problem).
Once in a pond situation, these invasive species grow rampantly and – once established – are often impossible to control. Such species most commonly found in Suffolk’s ponds and to be avoided are the following:
• New Zealand pygmyweed or swamp stonecrop can grow on both land and water and completely take over a pond.
• Water fern or fairy moss, a tiny floating leaved plant, which smothers the pond surface, especially in sheltered situations.
• Parrotsfeather can appear pretty in a goldfish bowl but once in a pond situation becomes very difficult to manage.
• Canadian pondweed is often sold as an oxygenating plant but once in a pond can fill the waterbody and require regular removal.
• Curly waterweed resembles Canadian pondweed and is often sold as oxygenating Elodea crispa in garden centres. This can similarly fill ponds.
Use plants that occur locally
Ideally, find a donor farm pond source nearby that does not support invasive, alien species that could be a real nuisance on the recipient pond.
Remember that all plants won’t suit all soil types and different plants often dominate in some years so if you plant a huge variety, the chances are they won’t all thrive.
Do some homework to establish whether the pond plants – native or otherwise – you intend to transplant are suitable for the size of recipient pond. Often, small ponds can be swamped by native invasive vegetation that is quite appropriate and in check in a large pond.