Hi,
I used to have a fresh water shrimp, he was great, did fine in my tank and also did ok in a wee tank with no heater etc while I was treating my normal tank! Thats the problem with shrimps, if you get white spot they need to be removed from the tank first! Thankfully I have not had an outbreak of white spot for a while now and my new wood shrimp seems to be doing fine!
BTW Get yourself a wood shrimp, mine is a really lovely bright red!!! Especially when they have just shed their skin.
He just sits on top of a silk plant that the air bubbles through and filters any passing bits of food, deffinatly not aggressive, just wanders about sometimes, a great addition to my tank!!
hope this helps, if you want any info or piccies? give me a shout!