As RD said, the nuchal hump is a water filled sack. It will grow (fill with more water) the more dominant a fish is, and/or visa versa.
Green Terror Nuchal hump Growth
- Thread starter Acerbeast
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Where did you get this information? I'm not saying that is is correct or incorrect statement. Ive read that it was a fat deposit connected to the upper dorsal muscle on several readings including the the research from Dr. George Barlow and Paul Siri, both were noted fish biologist and did extensive work with Amphilophus. Both men that probably know more about ecology than I will ever know.
I just found some info that suggest its is both fluid and fat...
"al hump (forehead swelling) develops in both male and female Cichlasoma citrinellum prior to spawning, and subsides shortly after spawning. Hump development is due to edema of the modified nuchal hypodermis. Fat stored in the same tissue does not contribute to prespawning hump development, although it may cause a residual, enduring hump. Plasma water increases slightly in fish with a nuchal swelling, indicating systemic water retention. The prespawning nuchal edema resembles preovulatory sexual skin swelling in monkeys. Nuchal hump development in males is gonad dependent. A hump could be induced with mammalian gonadotropins (HCG or ovine LH) in intact males but not in castrates. However, the steroid hormones testosterone, 11-ketotestosterone, 17β-estradiol benzoate, progesterone, hydrocortisone acetate, and aldosterone failed to induce a hump. A decline in the hump comparable to that occurring after spawning was induced by homogenate of C. citrinellum rostral pars distalis (8 r. p. d. per male fish); and a slight effect was obtained with ovine prolactin (2 daily injections of 7.5 μg/g). These results suggest that PRL secretion may inhibit the hump during the parental period."
I posted the following here several years ago. I have also seen the humps expand in size, and then go back down in size. Impossible to do if it was simply stored fat. I posted the same quote, and one from Barlow.
https://www.monsterfishkeepers.com/forums/threads/the-nuchal-hump-in-amphilophus.472442/
Below is a pic where the nuchal hump in a Flowerhorn was sliced open. That pretty much ends the debate. In Flowerhorn, large nuchal humps are known as water koks. I've also owned a few FH males with this trait, just like my midas, the hump squishes when it is pressed against the glass, which is what I would expect from tissue surrounded/filled with fluid.
HTH
https://www.monsterfishkeepers.com/forums/threads/the-nuchal-hump-in-amphilophus.472442/
Below is a pic where the nuchal hump in a Flowerhorn was sliced open. That pretty much ends the debate. In Flowerhorn, large nuchal humps are known as water koks. I've also owned a few FH males with this trait, just like my midas, the hump squishes when it is pressed against the glass, which is what I would expect from tissue surrounded/filled with fluid.
HTH
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RD. That is a pretty good video hard to argue with that one.
As for the argument "I have also seen the humps expand in size, and then go back down in size. Impossible to do if it was simply stored fat" Well you wrong that one, you obviously haven't seen my gut. Also know as a beer kok.
As for the argument "I have also seen the humps expand in size, and then go back down in size. Impossible to do if it was simply stored fat" Well you wrong that one, you obviously haven't seen my gut. Also know as a beer kok.
When i got my GT he was the dominant male in the tank and showing a hump at a small size. within a week of being in my tank and being at the bottom of the pecking order his hump dissapered and he wasnt as colorful. I put him in his own tank and with in a week his hump was back and his color was better then ever. My Gt is so timid. I guess this was a combination of dominance and stress that caused him to loose his color and hump
my 5 inch white saum male grows a hump whenever i remove the divider separarting him and a female. when i put back the divider to separate them his hump disappears.
