Two weeks ago I traded my strictly nocturnal species of octopus for a bimac from my local LFS. I'm not sure of the species I had, but he was primarily red in color and never seemed to change much compared to a previously-owned bimac. He was very active during the night and ate freeze-dried shrimp everyday, but as soon as I turned on even the dimmest of lights he disappeared into the sandbed. It was very hard to "trade" him in because he was doing so well, but I could never seem him except under a red light and even then could never really see him. So reluctantly I swapped him for a bimac that my dealer had ordered for me. When the bimac came in, I let them keep him for a week to make sure he was healthy and eating. When I went in, he was out and interacting with the customers; so I decided to make the trade. After I put him in my 75-gal tank he seemed to adjust quickly. He was out and about later that evening and was coming out in spurts for the next few days. He ate some ghost shrimp I put in and I think one hermit crab. However, for the past week he has stayed in his lair (a fake barnacle) and covers up the hole with an assortment of small rocks and empty hermit crab shells. A couple of times I have removed some of his "wall", but he quickly sticks out a few tentacles and covers the hole back up. I had the water checked and the water quality was excellent. The SG level is 1.025 and the temp is approx 76F. The only other inhabitants in the tank are two starfishes, an urchin, two snails, two conchs, a cucumber and three hermit crabs (inteneded as food). I guess I am asking am I losing this one? My previous bimac was much more active than this one. I might also add that I had my nocturnal guy for over 2 months under the same water conditions, if that helps.