awesome devil...very nice. yeah the nuchal hump on these guys can increase or decrease in size on a daily basis depending on a number of factors. I've had devil types who's hump would go down if I missed a water change and would then plump right back up after I did one. The male xiloaensis in my avatar doesn't have quite the hump that he did in that pic now because the smaller one that was with him (that I suspect was female but never knew for sure) died when I moved and I traded away his brother that was in the same tank and was equal size to him so the one in my avatar had a larger hump due to showing dominance over his brother.