Ok, no laughing! Vitamin D is something everyone needs and fish are an excellent source I'm told. That makes me wonder how do they get it? Can they get it from the sun? That would mean they would need to be near the surface alot or be warm water fish. So is it good to put your goldfish in a sunny windown or not? Too much warmth from the sun? I'm not a fish person just someone curious? Any insight would be appreciated. Thanks again.