Bandi Posted October 28, 2015 Report Share Posted October 28, 2015 (edited) There is a misconception out there that among male America's only the male gets the nuchual hump. Here are photos of my large pair. The female is the orange one, the male mostly white. Both are over a foot long. The male is easily a foot deep. Edited August 9, 2018 by Bandi Quote Link to comment Share on other sites More sharing options...
RD. Posted October 28, 2015 Report Share Posted October 28, 2015 (edited) I posted this a few yrs back on another forum, it explains how & why both sexes grow nuchal humps. But you are right, many hobbyists are under the impression that only a male can grow a nuchal hump, your female clearly proves that wrong. Nice chunky pair! Hormonal control of the nuchal hump in the cichlid fish Cichlasoma citrinellum C.R. Bleick - Zoology Department, University of California, Berkeley, California 94720 USA Abstract A nuchal 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. George Barlow also discusses this subject with regards to citrinellum kept in captivity in the following paper. http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1022&context=ichthynicar&sei-redir=1&referer=http%3A%2F%2Fwww.google.ca%2Furl%3Fsa%3Dt%26rct%3Dj%26q%3Dthe%2520midas%2520cichlid%2520in%2520nicaragua%2520barlow%26source%3Dweb%26cd%3D1%26ved%3D0CCAQFjAA%26url%3Dhttp%253A%252F%252Fdigitalcommons.unl.edu%252Fcgi%252Fviewcontent.cgi%253Farticle%253D1022%2526context%253Dichthynicar%26ei%3D8JWJT7nFFtLRiAKBx_3gCw%26usg%3DAFQjCNEYWNS0_mv2VpOzUIKaGjulEpIU6Q#search=%22midas%20cichlid%20nicaragua%20barlow%22 The factors determining the presence and size of the nuchal hump are complex, but they tend to assure that maximum dimorphism occurs at the time of pair formation. A typical progression makes the point: a male with no nuchal hump is brought into the laboratory and put into a situation conducive to breeding. Within a few days he develops a large hump. Then he is paired with a female. The hump recedes during the one or two weeks of courtship. Sometimes it diminishes rapidly, in less than one day, just before spawning (C.R. Bleick, pers. comm.). It stays reduced through the parental phase. If the pair completes the rearing of young and commences another breeding cycle, the male does not develop a large nuchal hump this time. But if the female is taken away at this point for a few days and is then returned, or replaced with a new female, the hump develops anew in the male. Here the elaboration of the nuchal hump is stimulated by the factors associated with thwarted sexual behavior and pair formation. Groups of males kept without females in large tanks regularly develop enormous nuchal humps that persist. The humps on such males often become grotesque, and far exceed anything seen in nature. The behavior of these males suggests that aggressive behavior might be involved in stimulating the development of the hump. Aggressive activity is also an important aspect of courtship behavior, particularly during pair formation. Edited October 28, 2015 by RD. Quote Link to comment Share on other sites More sharing options...
Bandi Posted October 28, 2015 Author Report Share Posted October 28, 2015 Thanks for that info RD Quote Link to comment Share on other sites More sharing options...
Pikeaholic Posted December 17, 2015 Report Share Posted December 17, 2015 Do pure Labiatus get humps. I just got 12 of them from the states, incredible red colors on some and yellows on others. I know you want pic`s, they will follow soon, lol Quote Link to comment Share on other sites More sharing options...
RD. Posted December 17, 2015 Report Share Posted December 17, 2015 Yes, pics for sure! And yes, pure labiatus can get humps, but generally never anything near as large as a midas. Quote Link to comment Share on other sites More sharing options...
Pikeaholic Posted December 17, 2015 Report Share Posted December 17, 2015 Thanks Quote Link to comment Share on other sites More sharing options...
RD. Posted December 17, 2015 Report Share Posted December 17, 2015 This large male is owned by an MFK buddy of mine. Over a foot long when that pic was taken. Most of his Amphilophus, including that male lab came from Rapps. http://www.monsterfishkeepers.com/forums/threads/amphilophus-for-cookiemonster.203143/ Quote Link to comment Share on other sites More sharing options...
Pikeaholic Posted December 18, 2015 Report Share Posted December 18, 2015 Spectacular Devils, love them all, lol Quote Link to comment Share on other sites More sharing options...
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