I bought 6 zebra Nerite snails about six months ago and I read that they can lay eggs, but the eggs don't hatch unless they are in salt water. I'm here to tell you that's not entirely true. I suspect I have about 4 females and they have laid scores of eggs in the last six months. Today I noticed that I have a few baby zebra nerite snails in my 100% freshwater 20 Long. It's not exactly an infestation , but please know that you're going to get some babies even if you keep them in fresh water.