| lots of sub-conversations around that subject, Mark.
Beni types , especially modern beni, lends to 'stretch'. It actually doesn't stretch like elastic ( an unfortunate description created by Toshio Sakai) but rather, as the fish develops the dermis gets more billowy and expanded and the chromatophores continue building along the pattern margins.
But as far as beni goes in general, new looks always excite the koi public. And sometimes those looks are age based in terms of when they look best.
The classic deep purple beni with very hard white skin is an example of this. But that mix of chromatophores tends to be very short lived as the skin expands.
The final piece to the puzzle is the pattern restriction. The white ground will open up to reveal certain piebald pattern gene expressions as the hormones and nerves develop in younger fish.
Bottom line is, there can be lots of reasons and I'd avoid a universal answer to all situations as lines are going to be different in how they develop. JR |