u/Distinct-Sky-3117

Hi all, got a question im sure someone will have the knowledge on. I was at a koi shop the other day they have many ponds of all different sizes, and one was massive about 15 or 20ft across and 10ft deep there was some of the biggest koi I have ever seen in there, I mean massive 3ft or longer koi 100+pounds. And none of the other koi are like that cuz the ponds that they are in, the smaller ponds there about 1ft or so. Which alot consider a normal size. Ive always herd. Dont put a goldfish or a koi and any fish that will get big in a 20gal tank cuz it will stunt there growth, well where is the cut off cuz a 1000gal pond is also stunting a growth to a curtain degree compared to a 10000gal pound.