Fish with chemical burns often have a "beaten up" apperance, sometimes with cloudy film over their eyes. In severe cases, the scales may fall away, exposing red or raw-looking skin.
They should look like white lesions on the sides of the fish or places where the scales are coming off. It is hard for fish to get chemical burns though, unless you used untreated water in the tank.
Fish with chemical burns usually don't live. If they do, they may have deformities with their fins, gills, and swimming abilities. Their scales may fall off or be very flaky looking.
It depends on what type chemical burns they have ammonia burns are most common and can leave spots on the scales and cloudy eyes cure water changes every two weeks.
