Here is my thought and it might be way off the mark, but the start of my augment is based in a field I am familiar with and then moves towards a grayer area. As a society that tries to save every baby born at all costs, look at the incidence of disability within our species, it is rather high as disabilities come in all shapes and forms, some can be seen clearly but most cannot, and even more are not diagnosed till much later in life. In nature a lot of this gets worked out with the whole “survival of the fittest” argument, but our tanks, a lot of fry get a chance at life that they never would in the wild. So because such a large percentage of fry survive, we are bound to see some that are less than perfect. It would be best for the breeders to grow the fish out to a much larger size to insure the fish are high quality, but the problem with that is, many of us would rather buy them while they are smaller and cheaper. I would rather take my chance on ten fish I get to grow out then one 6inch winner.