There isn't any nearby water for them to reproduce, sorry. I might try your suggestion actually. Is there a chance that it'd bring foreign bacteria into the water though?
I'm not too sure if he's been rubbing against anything, but he seems to try to scrape himself against the actual tank glass... nothing else. Is there any way to prevent a potential parasite? I don't want him suffering :(
It's really weird though... One moment he seems calm on the bottom of the tank, then he starts moving around rapidly out of nowhere... I've noticed it twice so far and it does occur close together. Maybe the parasite does something to him at those moments?