LF formalin 37% to treat Brook

[Vagabonddance]

Thank you so much for your reply and for sharing this information.
In terms of my clownfish, I had him in quarantine with hyposalinity water for 3 weeks. The white coating on his skin disappeared for fell off. He has been going strong since with no signs of breathing or any issues. Maybe it wasn’t brook. It did not look like ich. I have been giving him garlic and selcon. Anyhow he seems fine. But if it comes back I will follow your suggestion. Thanks for sharing.