He doesn't eat he darts and hits into things he's losing his colour his fins are rotting away he only comes up for air he breaths heavy you keep his water VERY clean what is wrong with your betta?

STRESS! (and TOO much attention). I keep my bettas for up to 3 years by NOT cleaning the water except every 6 months. I add water to keep the tank full (regular tap water with conditioner from the fish store). When mine did that, I put him behind a book and left him A LONE, except for feedings, for a week. Problem solved!