So we ended up buying two Mystery snails and 6 neon tetras for Newt's tank. He is curious about the snails but does not bother them. He tried to chase one of the fish for half a second and then stopped, because he is a big lazy baby. One of them that wasn't very interested in schooling with the others vanished over night, I'm guessing Newt ate him, which is a surprise to me because he is very lazy. The snails have done an awesome job of eating up lots of the waste left by the tetras and by Newt, and I'm thinking of also getting some ghost shrimp. I was wondering, how many can I get for my 40 gallon tank without disturbing the other three groups (those being my turtle, the tetras, and my snails)? They're only about 40 cents a peice, so I was thinking about getting maybe 15-25. Is that too many? Thank you!