Breeding, raising selecting out quality. With pure breeds, you know what they will look like and no need to grow out and wonder. With FHs, the batch can be similar but not all in the batch are exactly the same look or quality.
Some FHs are just normal and are the lower quality, but ppl still buy anyways because they want a FH. But high quality are a bunch of money because not all are the same.
It's not really the strain that costs money ppl!! Don't get into it the wrong way like many others have and and waste money.. What can the strain mean if the fish of that strain looks like crap?? It's the fish that shows outstanding quality & traits not many have that makes them worthy or pricey.
There are a few ppl out there that will use strain names to represent their fish they sell. So you expect something good of the fish when you hear the cool strain, then you waste money, space, and time bringing it home then it grows out to be an average looking fish. Don't be fooled by strain. Pay your money for what you see..
Im just trying to help out..