I read one of your threads, rip ramses... That you found a battery in the tank, i don't have anything like that but i do have this decor that's been bugging me to take it out lately.
When we first got it, it was never that brown or rusty looking like it does look now on the top. My gf got it because she thought it'd look cool and it does.... In the past I've always used plants and rocks, never any decor items like this... What do you think? Could be introducing a bad fungus that's starting a fin rot? Or other fungal issues? The water params are fine and the three guppies treat each other with respect and play together....