I live in Iowa and my pond has recently thawed. I was out there fixing a rock that had fallen out of place and I noticed there were a couple small snails on the rock. Are snails ok to have in your pond? My pond has 2, 8inch koi and I will be adding 2 more small koi so they can reproduce to fill the pond in the future, and I have lillies and other plants in the pond. Also, are they ok if I bring one or two in the house to put in my 40 gallon aquarium?