Flagstone Bad for my fish?

[caliskier]

I was wondering if flagstone from the local stone store would be bad for my fish. It is light gray on one side and dark gray on the other, the guy called it silver stone or something like that.

 

[TCTFish]

Depending on the type of fish you have and if the rock will leach any heavy metals that could hurt the fish. If it is inert, it should be safe for any fish. If it is not inert, then skip it or test a small piece in a separate container of water. Test the pH prior to putting a piece in water then again sometime after it's been in the water for a while. If the pH jets up and if you have soft water fish, then pass it up.