I was looking closely at my background and realized that 2 Ghost shrimp had somehow crawled out of the tank and got stuck between the background and the tank. I didn't realize I had to worry about the Shrimp sneaking out of the tank. Is this a normal occurrence? What can be done, I have covers on my tank but there are enough tiny cracks for them to get out, if they are determined. Why would they want to leave the tank? Thoughts, anyone?