I bought myself a pair of filter shrimp, looking to be older (they're around 3-4 inches) to put in with my community tank and upon finally letting them out into the tank they dove for a synthetic fallen log and immediately made it their new home. They spend every moment of the day clinging to the top of the log (inside of it) where my cory usually spend a little down time during the day. Is it normal for them to be so painfully shy? And would they be a danger to my smaller tetras, or dwarf frogs?