I've had the white cave in my glofish tank for about 2 months now and the only thing strange that I've noticed are little orange spots on it. All of my fish are fine, I used to have the decoration in with my cories, mollies, and guppies. Everyone is still healthy and happy. I've also made new decorations for my betta tank for shrimp to hide in. I've had no problems with it. I use the sculpey oven-bake clay. I would've painted them, but I have no idea what would work best in water...