I'm keeping some temporary cories for a friend in my tank with goldfish, apple snails, MTS, and lil ramshorn snails. I'm holding them for her while she moves. I like the cories and how they are always cleaning up the bottom... I have sand substrate and it gets dirty-looking fast. I'm wondering about a snail-safe loach for when the cories leave. I read that some types can go in colder water, although I don't keep my tank too cold(around 72). My tank is pretty well fully stocked, so I only want one loach if it would do OK on its own. So, does the loach of my specifications exist?? I've never had a loach before so what else should I consider before I buy?