The ceramic fish tanks bought in the market will kill the fish as soon as they are put in them. The inside is pure white. The fish tanks must be poisonous. Can anyone tell me why?

After buying a fish tank, clean it and put potassium permanganate to disinfect it, then clean it and add water to raise it. Fish will definitely die if you put tap water in it. Tap water needs to be dried for more than three days before you can raise fish. As for the guarantee The steps for "opening a tank" to keep fish alive are complicated and require a filtration system. Tanks without a filtration system must be left for at least a week during this season before fish can be added