Barbel Erosion

How long have U had them? Did U notice if they were missing when U bought it? How are your water params? U may have high nitrates. If so, gravel vac the substrate more often and do a 50% partial

Sharp edge substrate will damage the barbels too.

I got the cory cats (there were a total of three) on 9/6. I honestly don't know what her (his?) barbels looked liked when I got her, but I just noticed the problem so I think it is recent. They were very shy when I first got them and I didn't see them much. My water usually tests low on everything, but I will check nitrates again. What specifically would cause high nitrates, as opposed to ammonia or nitrites? Also, my substrate is flourite covered by sand, but the flourite is stirred up and on the surface in some places.

High nitrates could be caused by what your dosing fert wise. But if you didnt know what its barbels were before hand and the others are fine then its most likely purchased like that.

Swan