That's not rare at all. It's normal for older loaches to have faded lines between their bars.
edit: you can see some of them at
http://www.loaches.com/species-index/clown-loach-chromobotia-macracanthus
edit: you can see some of them at
http://www.loaches.com/species-index/clown-loach-chromobotia-macracanthus