Get A Room!

My nerites do that all the time. Since there are no eggs in the 50 litre tank, the red nerites are either infertile or both the same sex. So not really sure what they are up to 

Finding some of these now..... 

I doubt they've come in on any plants as I haven't added any for ages now (probably a couple of months) and even then I go over any plants before adding them to pick off any snail eggs I can find.

I don't actually mind having some snail babies as long as they aren't going to end up being pests like the ones that come in on plants. I'd imagine these should be ok as they're quite a decent size fully grown (a couple of inches) and if I do end up with quite a few I'd imagine they would be saleable?

That's assuming they are baby snails....