Water HyacinthWater Hyacinth Flower Water Hyacinths are one of the most useful plants for a water garden. Hyacinth provide shade to limit the available light They are great at removing nutrients to limit algae growth. Koi will often chew on their roots or just eat them. This is a very prolific plant and will spread quickly. Always compost your surplus plants. NEVER place water hyacinth in natural streams, ponds or lakes! Water Lettuce is another prolific surface plant Water lettuce will shade a pond Water Lettuce removes nutrients from the water Koi will often chew off their roots Always compost your surplus plants. NEVER place water hyacinth in natural streams, ponds or lakes! Water Lettuce with FlowerRuffled Water Lettuce