A few days ago I noticed something a little odd about one of the "nose flaps" (I have no idea what it's properly called) on my black moor. It was sticking up and I could see what looked like a little white under it. Now, about four days later, there is definitely a little fuzzy white bit there and now on the other side of the flap. It looks like ich to me, but it hasn't spread and the other fish seems clear. I put some melafix in yesterday, but I'm wondering if I should treat with Rid-ich or wait and see if it spreads. I hate to medicate if I don't have to but I also don't want it to get worse . . .
Stats and info:
-18 gallon, 2 fish
-No ammonia or nitrites; ~20 ppm nitrate
-Doing 15% water changes every other day to bring them down
-Carrot (the fish in question) had a pretty bad scape injury about 6 weeks ago then was moved into a larger tank about a month ago, so he's had some stress recently
-He's eating and acting fine
Thanks for any advice!