Hmm i dunno others but i just let them flare 5 mins per day only.

---

Added on September 7, 2012, 3:24 pm

Maybe the coloration just came out? If he still makan normal and active then there is no worries but to be safe maybe you should find one small dried daun ketapang, wash abit & let it float inside the tank. Your betta would love you for that  .

---

Added on September 7, 2012, 3:36 pm
Wow i'm not an expert here but it looks like fin rot. My betta also kena before. What i did change 30% water with conditioned water then add a pinch of salt (sorry i dun hv measurement as i do things only agak agak) then add dried daun ketapang let it float in the tank. To ease your little guy i suggest you reduct the level of water so he no need struggle taking air at the top, let it rest much. Only feed if he wants to eat.
I did just that with mine, it took quite sometimes for him to heal. If water became brownish the next day, it is normal because of the daun ketapang macam tea leaf and will aid it's healing process.