He could just be getting old. I had a betta fish live for 10 months once. Fish just don't live that long. Also, when you change water, and clean the bowl how do you do it? You are supposed to leave a 1/4 of the old water mixed in, and dechlorinate it for longest life. I didn't bother but I guess it doesn't hurt.

If your worried about blonde box of rocks, just replace the fish with another fish thats similar enough in looks to it.