The erosion of a cory's barbels are typically related to water quality. If you are reading ammonia or nitrite in your water test, that is likely the cause. Whenever I have problems, the first thing I do is test the water. If you don't have a test kit, take a water sample to a fish store near you...most will do free water testing. However, I recommend that you get one as soon as possible. They are invaluable tools and for about $20 you can get a complete kit.
