I bought a Bleaker (which I think actually looks more like a Polleni) yesterday, and while it was definitely black in the store's tank, after almost 24 hours in my tank, i's definitely brown. it went pale grey as soon as the store salesperson bagged it, due to stress. Which I get, but by now I would have thought it would have turned to back to black. Anyone help me explain this and what I can do about it?