...is it okay for goldfish to eat cake?

No, this was not intentional. I had given Torin a piece of his leftover birthday cake (ironically, in the shape of a fish), and he leaned over the tank from my arms, crumbled a bit in his fist, and *plop! plop!* *gulp! gulp!* down it went into the mouths of several greedy goldfish!
The fish seem fine, but fish and cake isn't like birds and rice, is it? Just want to check...