Hi. I have one nerite snail in the tank with my shrimps. I noticed it could be active sometimes, but sometimes it wasn't or sleep a lot. I also found it was hanging around above the water's surface for few times. I am wondering if this is caused by poor water quality or not enough algae(food)? In fact, the shrimps are fine, but only two out of ten have turned to red colour sometimes. Sometimes the shrimps will come up behind the snails and grab on the shell for awhile. Should I add any green vegetable pieces/food to the tank for the snail? 
