Angelfish with hole in the head - what to treat with?

I would vote for using the Metronidazole, that is the classic HLLE remedy.

Yes, but Hole-in-Head is not the same as hole in fin. Fins don't have sensory pores. That's not to say using Metro won't help (it's also an antibiotic), but it wouldn't be my first choice unless I was sure of an HLLE diagnosis.

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Well, a pimple that bursts and turns into a hole sounds a lot like HLLE to me. Rather, I should say it sounds like Hexamita, which is one of the more common causes of HLLE. One thing you might want to try is Metronidazole combined with a Furan compound - it's usually a very effective combination. I always try to keep Furan 2 handy since it treats both gram negative and gram positive bacteria.
 
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