Trapdoor snails are scavengers that consume fish food, fish waste & algae in ponds to help keep them clean not green. We've been through the green stage and its a whole lot more enjoyment when the water is clean & clear. In the picture above you can see Freckle, a fancy speckled goldfish to the left of the bubble in the water. Sometimes the fish play with the snails and knock them from their jobs cleaning the walls. Most times they leave them to their work with no cause for disruption. Our darling clean up crew goes everywhere they wish ~ I have even found them outside the pond on the plants. Three in all. Two larger snails and one sort of small one. Some say there is a need for more in our size puddle with fish ~ but three seems like a fabulous number to me.
Maybe its really not that bad being a snail ~ living the aquatic life with fish, a tadpole & plants. Seems pretty simplistic to me.