could someone please explain to me the difference between the pleco with the red eyes and the same with the black eyes.... I am looking for the pleco that basically goes yellow - nice bright lemon yellow...(the ones I have seen in the LPS look sort of a blonde color - do they get yellower with age?? . are they both the same except for the eye color? ... anyways I WANT to purchase the bright yellow one, so what should I look for? Thanks in advance!