Earlier when the lights were on I noticed his leg was stuck in something, so I pulled it off for him. I went to check on him with the lights off and he was on his side struggling to move with crabs enclosing on him. I moved him to another part o the tank, to keep the crabs away. He is the coolest shrimp ever, cleans my hand when I put it in the tank, crawls all over my arm. I really don't want him to die..... Ive had him for over a year. What should I do?