I have a banded coral shrimp that I have had for the past 2 years. Today he started acting very strange... he seemed to "square off" against and attack non-existent opponents. He would repeatedly flick his tail and shoot backwards across the aquarium, like they do when they molt, but he molted two days ago... since then he has been hiding behind a rock, which is unusual for him. He usually spends most of his time hanging out on the back wall, or upside down on the crappy UV sterilizer floating in the tank. I checked the water, and everything is ok. Not perfect, but no worse than usual. The fish in the tank seem ok (they avoid him like the plague!) and the hermit crab and blood shrimp are still doing fine. I have never seen him act like this before. It is almost like something is messing with his instinctive behavior. I semi-jokingly suggested that he was going senile. After all he is pretty big, and how long can glorified cockroaches really live? I'm not sure what to make of all this. I changed out about 8 gallons of water. Its a 50 gal tank. At "press time" he is still hiding in a dark corner, and may be missing a claw (it is hard to see). He may be physically damaging himself. Has anybody ever experienced something like this? His behavior was always very predictable before, but he has been acting weird for the past day. Any ideas?