nope the shrimp shouldn't bother it at all.
I'd suggest having them feed the tank in the store and see if they're eating.
Several people have had trouble during the last year or so with them not eating.
I actually prefer this type, as they remain smaller, but I've tried 3 of them, and a green, and black of the other variety this year, and none of them ever ate.
http://ww.liveaquaria.com/product/prod_ ... CatId=1441
It's frustrating because I've had two of the little guys in my 55g and they did just fine. The first one I had for two years. The second had been in the tank for a year when I lost it in the move. All I can think of is that one of the main suppliers has started using cyanide to capture them. Of the 5 fish, the last one even ate at the store, and continued to eat in my tank, but his stomach kept getting smaller and smaller. Not a good sign.
B