Terrible Advice Tuesdays: When a fish glances (scratches itself against rock/gravel), that means it has ich.
The rest of the story: I hear this one a lot so let’s break it down:
1) A fish that glances could have a disease, and it could not. Fish glance for several reasons including rubbing off dead scales/skin. Just because a fish is glancing that is not a 100% positive diagnosis for a disease as discussed in my No-Nonsense Quarantine guide.
2) A fish that has marine velvet (Amyloodinium ocellatum) or Brooklynella (Brooklynella hostilis) is just as likely to glance as a fish with ich (Cryptocaryon irritans). Therefore, if you see a fish glancing, ich should be one of the diseases that you watch for, but don’t exclude other diseases as well. Also, if the fish has Brooklynella and you treat it for ich, the fish would get the wrong treatment entirely.
If you see a fish glancing in your tank, make note of it and keep a closer eye on the fish. However, don’t freak out and immediately assume it is sick and quarantine it unless you see a disease present.
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