"I thought it was a real thing," Rowling said. I had been told in my youth that fish only grow to the size that's available. So I was confident of this and thought there will be a term for a creature that only grows to the available space.
"But then I looked it all up and I found to my horror that fish remain stunted if the water quality is poor so they don't have that quality at all. So I had to coin this phrase because I'd conceived of this creature that could shrink or grow according to the available space."
