I have two Bettas and they share a ten gallon tank with divider, one has a huge sackish looking thing under his chin area, what could be wrong?

Question
He was fine a week ago and now he looks like he is ready to pop, is there something to do or is he just too old?  I have put meds in water but nothing.

Answer
Hi Melody;

He could have an abcess from an infection or he is constipated and it is causing him to bloat up in that area. It could even be his gills hanging out from an infection there. You might want to try an antibiotic called "Maracyn 2". It absorbs inside the fish where infection is. Give it a few days to start working. Here are some links to disease info with photos to help narrow down what it could be;

http://www.bettatalk.com/betta_diseases.htm
http://www.mushi.petfish.net/bettadisease.html

I hope he feels better soon......

At Your Service;
Chris Robbins