bettas mouth. please respond asap!

Question
my betta is in a new 10 gallon tank with a sword.  i had three other fish. i bought all of the fish last friday, and the 2 angels and the clown loach died this week.  the pet store did not tell me that it is not okay to put 5 fish in  together in a tank that i just set up.  i learned this from reading your answers this week.

the betta and a sword are the only remainders, and i am hoping to keep them!  the betta was doing fine until tonight.  i noticed that his mouth is white all of a sudden. it looks like there is something white sticking out of his mouth.  he also seems listless.  he was fine today and had a great appetite.  

what happened, and what do i do ?  

Answer
Hi Tracy;

He may be suffering from Columnaris. It will attack when fish are under stress. Here is an article about it and how to treat it;

http://freshaquarium.about.com/cs/disease/p/columnaris.htm

I hope he feels better soon.....

At Your Service;
Chris Robbins