4 Inbred Depression?

Sometimes, in animal breeding, even if you don't select for any oddity, you still get change in the animals.

Often, domestic animals just don't have that vitale look of a healthy wild type.

There is what is called "inbred depression", which is the opposite of "hybrid vigor".

This fish doesn't seem to show any oddity, but it doesn't have the vital look of the wild type.