Why do some Cichlids grow bumps on their head??

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vanimal

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I was just wondering why some cichlids and other kinds of fish grow bumps on their head?? And does any body know how to make them grow one? Is it just for males or can females get them too? Any explanations will be appreciated! :) Thanks!
 
Well to give you an example, Here are
Photos of a frontosa which is a large cichlid from lake tanganika. As juveniles they have no bump. Females usually seem to have smaller bumps or
None at all, and males have medium to large ones.


Female

image-776184653.jpg




Juv.
image-1151495685.jpg



Male
image-717344905.jpg


If this is the kind of bump your talking about.

~Photos do not belong to me~
 
vanimal said:
I have a yellow lab and 2 other african cichlids

The labs wont grow a kok. Depending on what the other are they might but prolly not if the are mbuna. Frontosa are african cichlids and do. Off the top of my head i cant think of any mbuna that do. Still wanting to see those pics so i can help u id them.
 
I'm not sure why they develop them (they're called nuchal humps, by the way).

Does anyone know of any cichlid species that are dimorphic and have nuchal humps? The african species that have them that I know of (frontosa's, Steatocranus casuarius and cyrtocara moorii) are all monomorphic species.

Maybe they play some sexual role among these monomorphic types (broadcasting a male's vitality to the female while at the same time used to intimidate rival males when competing for females). Just guesses though.

Frontal view of frontosa nuchal hump
img_1968008_0_83cf1ea879ee254b36bb122cabf8b54d.jpg
 
As far as I know the humps are used for nudging females during the breeding process, as well as to attract a mate.

I know a lot of SA/CA cichlids get them. And just a handful of African cichlids do.

I am pretty sure the size is determined by dominance/genetics. For ex. My RD has a slight hump, but... When I add feeders or target fish it will grow twice or more in size. Being that he is a single fish with nothing else in his tank his hump is usually not at a noticeable bulge.

It is also not uncommon for dominate female cichlids to grow a hump as well. I used to keep dovii a few years ago and my female had one, (not impressive by any means but she had one).
 
I'm not sure why they develop them (they're called nuchal humps, by the way).

Does anyone know of any cichlid species that are dimorphic and have nuchal humps?

There loads of dimorphic new world genus's that display that, even the common archocentrus nigrofasciatus has this trait.
 
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