I just had a thought, is it possible that the motoros can be turned blue pending on diet? Flamingos turn pink when they eat the shrimps is it possible that if the rays are eating a lot of electric blue crays?
yes and no... there has been talk about it however it stays with them as they are in tanks as well as wild, and being kept on the same food... and it then fades
if it fades then it could be a vascular issue that is a genetic.. correcting as it gets older..
im just trying to come up with a reason for this variant..