Hey All, I recently bought a new Aquarium around 6 weeks ago, and right now it has one Shubunkin only. I thoroughly cleaned the Aquarium around 2 weeks ago, but now I noticed dark brown patched appearing on some of the decorations placed inside the fish tank, and at certain spots on the walls of the aquarium as well. I was wondering if you guys have an idea what it is, and what needs to be done for it.
Regards
Regards