How much amount of Formalin and malachite green to add into the tank directly, the tank is 850 liters. Another question, this reagent of the picture contains Zn "zinc". It doesn't show any lavel. The tarjet is a couple of Motoro stingrays, they share their tank with guppies, the most of them are affected by Trichodina sp and fungus. Any recommendation will be wellcome.

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![DSC_0057[1].JPG DSC_0057[1].JPG](https://www.monsterfishkeepers.com/forums/data/attachments/867/867941-21f37f6845307603143c5536e2ab5fd3.jpg?hash=IfN_aEUwdg)
![DSC_0058[1].JPG DSC_0058[1].JPG](https://www.monsterfishkeepers.com/forums/data/attachments/867/867942-16aa8e1c9d333ec8cb7bc7a394edf833.jpg?hash=FqqOHJ0zPs)