Betta seems fine, but hes not eating

Question
Hello:
I have a single male betta in a 2 gallon bowl. One live plant. His water is treated for chlorine and I add a little salt to it and I change it once every two weeks.

For the last week or so, he won't eat. He was eating fine until then...I fed him BettaMin flake food and he'd even nibble on my fingers to get it. He still "greets" me at the bowl in the morning, but when I put the food in, he doesn't eat.

He doesn't show any visible signs of illness. He swims around, flares at me (or the mirror I put up for him) and blows bubble nests, but he just doesn't eat.

I *think* this may have started when I began putting the mirror up to his bowl for 5 min. a day. That's when the bubble nests started, too. I tried to feed him after not using the mirror for a day to see if maybe the mirror was stressing him out, but he still wouldn't eat.

I clean out the uneaten food, but I'm not sure what to do. Help? Thank you.

Answer
First of all, the mirror is not a good thing.  Betta's are very territorial and will chase other males away.  He will become stressed if he sees another male fish that won't go away.  
 It sounds like you are doing a good job cleaning his tank (although once a week would be better).  Make sure his tank is warm enough.  Sometime people open their windows this time of year and if he's in a bowl, the temp might have dropped.  If you don't have a heater, put you finger in.  You should just barely be able to feel the water, so luke warm. He might also be constipated, so offer a pea (canned or frozen) without the shell.  If it's frozen, thaw it under warm water.  Other then that, you just have to watch for other signs of illness.  A fish not eating is usually the first sign that something is wrong, but you can't treat it until you know what it is.  Keep in mind a healthy fish can go 2 weeks or more without food, so if it is just that he is upset, he'll be ok for a while.  I hope this helps you.