Is my beta sick?

Question
Hi,
I've had a male beta for about 4 months now in a medium bowl that holds a little more than 20 ounces of water.  The instructions I got with him said he should be cleaned once a month or so, but over the last few weeks the water has been evaporating really fast and getting dirty more quickly.  I associated the rapid water reduction with the fact that the air in my dorm is so dry, but I don't know if that's logical.  At any rate, I had cleaned the bowl twice in 2 weeks, and let it go a week and a half before doing it again because I didn't have much time, and I had been accustomed to having at least 2 weeks in between cleanings.  This last time, I admit it had gotten more gross than usual, and I'm afraid that might be part of the problem.  It was yesterday that I cleaned the bowl, and today he has fuzzy white gunk on his beard.  I'm pretty sure it wasn't there before.  I'm hoping this is something I can treat with some drops or vitamins?  It doesn't seem to affect his behavior, because he is still pretty active, but I still don't like it.  I've been letting his new water sit in a bottle for a week or so before cleaning him, and feeding him something called BettaMin.  It's mostly flakes, but there are also some shrimp bits that I make sure to include when I feed him.  I wanted to make sure neither of these things was likely to encourage the problem.
Thanks for your time!
-Ellen

Answer
Hi Ellen;

You have done the right thing is changing more water more often. Bettas in bowls need water changes twice a week to keep their water clean. Waiting a whole month is really not good. Ammonia and other toxins from fish waste accumulate more and more every day that goes by. It will burn the fish and cause the infection you see on him. Get a product called "Betta Max" by Aquatronics to treat it. Keep him as warm as possible too. This helps his immune system functioning properly. You might also consider feeding him less food. If the bowl is getting dirty very soon, you might be giving him too much.

Followups welcome.

At Your Service;
Chris Robbins