How does a goldfish grow as a size of a foot when in seawater and still the same size when in a bowl?

Goldfish release growth-inhibiting hormones into the water they live in: the more goldfish in a smaller space, the less likely they are to grow. For instance, if I have a common goldfish in a 5 gallon tank, it will grow to about the same size if I had 6 of the same fish in a 30 gallon tank. But leave that fish alone in a 30 gallon tank, and it will grow larger. This is why pond goldfish grow bigger.

But goldfish won't grow at all in seawater; they aren't Saltwater Fish.