all normal?
ph
nitrates
nitrites
amonia
hmmmm....... i would try a water conditoner, alot of city water has clorine and maby even floride added,, pluss if it has rained alot the city water company somtines even adds more chemicals to help the dirt settle,, usually would never bother a human but fish are pretty tiny. do you use salt at all? only use aquarim salt. table salt with iodine in it can kill them. no more salt then a half teaspoon per gallon,, will help heal up the fins. is he stressed at all? how do u change his water? do you scoop him out and put him in a little cup or do you just suck 25 to 50 % out at a time with a airline tube? do you have a heater in the tank? whats the temp? most bettas like it somwhere between 78 to 82 degrees farinheight,, not sure what celcious equals to.is he still eating? what do you feed him and how much? if all else fails get a picture and try to post in the emergencys section. if he seems really sick try to get a hold of ,,,,, wilder ,,,, he is crazy knowlagble about all sorts of dieses and illnesses.