In the spring I got some Peruvian scalares from Larry Waybright and the males had -to varying degrees-a nuchal hump which gave them a facial profile rather the opposite to that found in altums. Later on in the summer I obtained a group of 4 sibling domestic silver pearlscales and reared them in the same tank as the peruvian with the largest hump who was also the dominant angel in the tank. One of the pearlscales quickly outgrew his siblings and began to challenge the Peruvian. Over a period of 6-8wks he supplanted the Peruvian and harasses him from time to time. Coincidently he has grown a magnificent hump (if you like humps in angels-I don't) and the deposed Peruvian has completely lost his. Can anyone corroborate/disconfirm that in scalare lineages where males can develop such a hump that it is an indicator of dominance within the group? Incidently one of tthe other male pearlscales mated with another domestic female & showed no hump at any time-there was no other male present. He was smaller and had a classic "altum notch" so from this group I speculate that tendancy to develop a nuchal hump is genetically variable, sensitive to social status & gender specific.