Would you use a painted/glazed terra cotta pot as a decoration? I found a plant pot that is terra cotta but it is painted or glazed, i'm not sure with what. What are the chances it could be bad for my fish?
Same thing if it's made in Mexico. Had to be real careful about that when buying new food crocks for my macaw. The ones brought in from Mexico weren't food safe. That's also true for any clay flower pots people are using as caves under water.
I think you might be able to seal that using something to make it safe. I'm not sure exactly what works best for that, but maybe someone else could let us know.