The problem is no-one knows which species are being sold. In the UK, feeder shrimps are Palaemon and Crangon spp., and these are brackish to marine, while in the US there seem to be a mix of freshwater and brackish species of Palaeomon and Palaeomonetes, depending on how close to the coast you are. Shrimps are incredibly difficult to identify even to genus level, and most hobbyists get completely muddled when trying to identify their beasts.
Fpr example, doing a quick
Google search, I found ghost shrimps identified as "Callianassa californiensis", which they most certainly are not. Callianassids are very distinctive, live in the sea, have giant claws, and don't look anything like the glass shrimps hobbyists have.
Cheers,
Neale
I have been keeping around 5 ghost shrimp in my tank at 1.010 and all seem to be doing fine. They shed about once a week or get eaten by puffer. What is the limit to these in salt conditions? Tried trying to find out some by google, but all they say is they are freshwater.