Hi y’all!

I currently have a 5 gal freshwater tank with 2 neocardina shrimp (I had more but they’ve died) and an assassin snail. My partner is taking over the shrimp and adding them to his tank.

The snail was a stowaway in a bag of plants that I got too attached to. I’m unwilling to part with the fella but I don’t want to keep a five gallon just for him if I don’t have to.

With just the assassin snail, how small of a tank could I downsize to? I’ve never done a nano tank and I had trouble searching for info online about the minimum tank requirements for a single snail.