My Oscar goes BERSERK at the sight of water bottles, the metal or plastic kind. Especially if they are held sideways to resemble...a fish? I don't know why. It can be any color or material and I don't know how he keeps a catalog of what is and isn't a water bottle, but it's totally real. I can hold up similar things like vases, shoes and such, it just doesn't do the same thing as a water bottle. I don't do this on a regular basis, but the day we discovered it we were trying to comprehend why he was scared of them. We could ascertain nothing useful from our efforts so we gave up.