Amazing!! I saw this myself a while back and could hardly believe that a fish could create such a wonderful pattern to attract a mate. We still have so much to learn about nature.
Amazing how a skill such as that would evolve. Did one of them one day just decide "hey, I wonder what would happen if I made two ridges, one beside the other?". A female spotted this and went "wow, pretty cool. Is this guy single?". News of the fish's dating prowess spread and other males came along to view his creation and copy it for themselves. Of course they had to add their own flair. Over time it got more and more complex. Given another million years I wonder would the design change further.
