The topic of koi pond plants is a somewhat contested and confusing topic among pond owners. Some people that you talk to will tell you shouldn't put plants in a koi pond for various reason, and others will tell you that plants are actually very beneficial in a koi pond and should be incorporated if possible. So which is it? Well to be honest, in our opinion both sides are right in a way, and we tend to sit somewhere in the middle of the fish pond plants debate. It is definitely beneficial to have plant life in your pond, and it's also possible though proper selection and placement to create an environment where koi and plants can co-exist. There a couple ways to achieve this balance. Read on for more information.
The main problem with combining koi and water plants is that koi are likely to eat many varieties of plants. In some cases, koi can be quite destructive, and are able to quickly destroy a plant that is not protected in some way. That being said, we have also heard reports of some koi being quite gentle with plant life, nibbling here and there, but not to the point of killing the plant.
As we discus in more detail on this site (see our page on plants for ponds for more info), plants are beneficial to ponds for a number of reasons. Apart of the obvious aesthetic benefits of plants, one of the main reasons include increased shade which helps keep the water cooler in the summer and helps fight algae growth by limiting algae photosynthesis. Another important reason is the natural biological filtration that plants provide by absorbing nitrates which in turn helps fight dreaded blanket weed (also called string algae). In sunny or hot climates, plants can also provide your koi some shade to prevent sun related injuries and problems.
Assuming at this point that you'd like to try adding some koi pond plants, here are a few tips to minimize the likelihood of your koi eating the plants.
One way to keep koi away from your plants is to build a shallow shelf into your pond along the edge where water plants can be planted. Larger rocks can then be placed at the edge of the ledge, which will prevent koi from being able to swim in and amongst the roots of the plants, which are planted between the edge of the pond and rock barrier. Using this method you are still able to get some plant life in your pond while keeping your koi at a safe distance. There is a potential problem with this approach if you live in an area that has racoons, who have been known to use shallow shelves to stand on while fishing for your prized koi. When constructing such a shelf, use your best judgement based on your particular location and planting goals.
A vegetable filter takes the idea of separating your koi and plants one step further by actually creating a separate pond or containment area where a large amount of moisture loving plants can be planted. A vegetable filter is actually seen as part of the filtration cycle and is usually placed after the last stage of biological filtration. After the water leaves the biological filter, it then is pumped into the vegetable filter before eventually being returned to the main pond via gravity.
If you feel that your koi are well behaved, you could always try placing some plant life in your pond and seeing how it goes. As we mentioned earlier, there are many koi owners that get great success out of combing koi with floating plants as well as deep water and marginal plants. To give your plants the best chance against potentially nibbling koi, choose hearty varieties that grow quickly in your particular climate. Have any particular plants that work well? Tell us about it so we can share it with others!