Fire Belly Toads are toxic, do not keep them with any other animal.
They are from southeast Asia.
Fire Belly Newts are from China, at least the ones in most pet stores.
Fire Belly Newts produce some potent skin toxins and have fairly prominent parotid (poison) glands on the sides of their head.
Although they might share the same water sources in the wild, they would not be accustomed to sharing the same small pool day after day and the toxins will build up and stress, hurt, even kill either species, especially if the water isn't changed a few times a week. Especially the newts and their eyes since they spend most of the time under water and feeding in the water, they would be ingesting all that fire belly toxins day after day in food, as well through their skin. You won't know until it's to late and it's sometimes very hard to tell if something is wrong.
Your friend is probally causing both the newts and toads stress and pain without even knowing it.