When I got my first fish for my 4ft tank about 3 months ago, the dealer gave me an assasin snail, as I told him I'd picked up some snails in plants I'd bought online. I rarely see it, now and then he sort of saunters across the sand, so I got a big surprise when I saw 3 little assasin snails in the front corner of the tank. I'm thinking there are probably a lot more as I watched one of them bury himself completely. It seems I got a female assasin. Surprised though at the length of time between aquiring the snail and seeing these young ones as I spend a lot of time looking and fiddling with my tank. Looks like the ramshorns will soon be no more.