I am the recent purchaser of a male Abdopus aculeatus. I'm in my third week with him, it'll be a month this Sunday. He's been a great pet for me, he reacts to our (my wife and I) presence at the tank, he would come up and eat out of my hand, he would display for us, he would endlessly explore things we put in the tank for him (he adored a black coffee mug, he used it for a den). Unfortunately, I now believe him to be becoming senescent. He's turning grey, he can't hold his colors, instead of using his whole arms to move around he only uses the base and lets the rest flop, he's stopped eating, he avoids his dens to stick on the glass or a corner and his skin looks droopy, for example, it's not tight around the eyes. The thing that gets me the most is that he always seemed to move with a purpose, he would go from rock to cup to rock to crab to rock to den before. Now, he'll leave a corner of the tank, crawl on the glass, then go back to a corner of the tank. He's grown a bit since I've gotten him, he's about two and a half inches long in mantle length. When I bought him, not knowing what species he was, I figured that his small size (about 1.75 inches mantle length) meant that he was, if not a baby, at least a younger one. He did come to me appearing to have led a fairly rough life. he was missing one arm entirely, half of another, had three that were very much smaller than the rest and only three full size arms. After doing some research though, it appears that 1.5-2 inches ML is mature for these guys. This really has me sad, he's been such a cool pet. I realize there's nothing I can do to stop this, but I imagine there's probably some that I can do to slow it down. I'm gonna read up to see if I can make his golden years nicer. Well, that's Boo's bittersweet story.