I also think the bleu motoros are specially treated to make them bleu.Specially while the color disapires after a few months the only bleu ray I have ever seen is Bleu Pearl ray in our breeding stock. Pic below.
Regards
Frank
In Peru the rays looked pretty similar unless you know what you were looking for. the ones that we figured would turn blue did after about 2 weeks without stress in the US. the other big factor was the lighting used. You'lle notice some pictures are way bluer then others... probably because the flash was at the right angle or freaquincy to show the blue. Unfortunatly we haven't kept any of them long enough to find out what the cause is. We have received larger blue rays that were shipped to asia... so I'm not sure if it is a thing they would grow out.
As mentioned before the blue may be caused by a diet, or symbiotic bacteria. there may be numerous causes. Any of which may be hard to maintain in a home aquaria.
PS That ray is so freakin' awesome... please contribute to the gene pool!
Thanks for the compliment this was one of the last Pearl rays caught in the wild. The moment we seen it, we knew it was something special. Hopefully in the future the male will get some females pregnant and we get some beatifull offspring.
Regards
Frank