I finally found some Clithon diadema ( horned bee nerite). They are the size of a pencil eraser. They are in qt right now. Cleaning some diatoms from my anubias. They are small enough to get all the hard to reach places that my larger nerites miss. I have been waiting for these snails for years. So my paranoia has to do with my surface skimmer. I think they are small enough to crawl down into it. Once they reach my filter they are goners. I am going to take some thin plastic and set it over the open top of the skimmer. I was going to glue it. I think it would be too hard to clean though.This should keep them out. A temporary glue would be nice. Any ideas on this one would be welcome! I have the Tom's aquarium products skimmer. I can't make my mind up about this. Perhaps I should give them their own nano and use it for a plant cleaning station? When my rhizome plants get algae covered, just toss them in there.