Silicone in fish tanks?

I bought "Premium Waterproof Silicone: Window/Door/Attic/Basement 100% Silicone". My research thus far had said that it's safe, as long as it's 100% silicone, without anything mold or mildew resistant. However, now that I take a closer look at the bottle, on the back it reads "Not for use below the water line, where FDA compliance is necessary, or aquariums." (despite the fact that it is "permanently waterproof". ) What do you guys think? Is this just something they say to cover their backsides?