I bought a shrimp, I believe a Ghost Shrimp, 2 weeks ago, and he was light brown, translucent in color. A couple of days later he "reshelled", or whatever that's called when they leave their old shell and grow a new one . A few days after that, I noticed that he'd turned very dark brown in color, and he's stayed that way ever since. Do you think that's because of the new shell, a different diet, or something else? I don't have previous experience with shrimp. He seems to be doing perfectly fine, no sign of disease as far as I can tell.