How do Rd/midas get their nuchal hump

[LordofCICHLID]

My red devil is doing some weird stuff at night then i noticed the hump was larger is their something they physically do to acheive a larger hump

 

[duanes]

The hump is a water filled sack, that can get larger, or smaller depending on the dominance of the fish in the community hierarchy. The more alpha, the larger it can get, if you put a more dominant individual it the tank, it can shrink away to no hump at all.