Question: Are fish cannibals??

Though this may seem like a random question, there is a reason behind it. I was at my parent's for the weekend and (as I often do) don't think I fed my fish before I left (though I had the day before, Thursday, so I figured they were o.k. -- they've gone longer than that without food!!) Anyway, when I came home from school on Monday, I finally remembered to feed them. I have this habit (given my frequency of feeding) of checking the top for floaters and counting my fish. I have 2 goldfish and 5 little neons. I'm usually more worried about the neons since they are so small, but I'm sure I usually am aware of the goldfish also. When I went to count them on Monday night, I was trying to count the neons, when I suddenly realized -- there is only one goldfish in here!!! I looked over the top, bottom, between the little decoration thingies, and even in the filter, but didn't find it. I then looked around the floor and the only dead animals I found were stink bugs (are they as bad where you live as they are here???!!) Basically -- I CAN'T FIND IT!! I didn't see a skeleton in or around the fish tank and I'm not really sure what to do next! I guess I'll just be greatful that if the other fish did cannibalize the poor thing, at least they survived another day or two!!

I think I need to go home and feed my fish now . . . .