Fin Rot?

[fluffycabbage]

My betta has quite see through fins, the ends are a little ragged but not bad. He was nipped a bit by other fish when i first got him but hes been in a tank with just 4 small corys for over a month now, and while the fins have repaired a bit theyre still not back to normal.
I cant add salt to the tank because of the corys, so what would you suggest?

Ive done a 90% water change, and will do a 50% change daily to see if it improves.

 

[Azaeil]

I dunno, they look alright to me.. do they have a white edge to them? If you could get him to flare up and snap the photo we could see the fin damage better.. It could just be scarring from the nipping. One of my girls has scar nicks on her tail from two cambodians ripping at her, not at once, but when I attempted to change the females..

 

[loraxchick]

from the photo it honestly looks just like new-growth. kinda see-thru at the tips. can take a few weeks to "color up". for now id just keep his water nice and clean and watch for signs of the fins actually eroding or chunks going missing seemingly overnight. also any actual white fluff/fuzz on the area in question.
looks good to me tho. just keep an eye on him and any changes in behavior/eating.
all the best
cheers