I literally had over a hundred of them in my 20g long, they were crawling all around the tank even during the day, which was weird because I thought they were supposed to be nocturnal. A lot of times when I looked in my tank I would see what looked like a giant snail orgy, which it essentialy was, or must have been, cause now there are thousands (okay, maybe not thousands, but definitely hundreds) of baby MTS. I don't know how fast they grow, but they are like the size of a speck of sand right now so they're not an eyesore. Nonetheless, I was worried that this was gonna continue exponentially, so I got 5 assassin snails from msjinkzd, (did you know they're actually whelks, not snails? I dunno, I thought that was interesting), and less than a week later I barely see them anymore, it's crazy! I also got some amanos, nerites, and other shrimp, and they were all awesome and really healthy, you guys should definitely check out her website, she's got lots of cool stuff!
Still, I do wanna know, how fast do they grow? Now I'm worrying the assassins are going to run out of food! lol