Came across this video, while I do not agree with the conclusion I found it to be interesting
To me sexual dominance (appear intimidating to other males and attractive to females) makes more sense. Nuchal hump is sexual dimorphism to start with, most of the action happens because of systematic water retention. In Midas cichlids, hump grows in ideal breeding condition, progresses to be maximum size to occur at pair formation and when paired hump recedes, sometimes as fast as day, so I don't think it gives fish any advantage as energy reserve. In one study, when groups of male midas were kept without females in large tanks they developed enormous nuchal humps that persisted. I don't think it's a mechanical advantage but more like looking scary. Composition of Hump in African cichlids is slightly different than American cichlids, and more of permanent compared to American cichlids.
My references
https://digitalcommons.unl.edu/cgi/viewcontent.cgi...
https://www.sciencedirect.com/.../pii/0016648075901367
Two research papers I couldn't get as they lack public access are (but looked at abstract)
1. Does sexual selection account for the conspicuous head dimorphism in the Midas cichlid?
2. Hormonal control of the nuchal hump in the cichlid fish Cichlasoma citrinellum
To me sexual dominance (appear intimidating to other males and attractive to females) makes more sense. Nuchal hump is sexual dimorphism to start with, most of the action happens because of systematic water retention. In Midas cichlids, hump grows in ideal breeding condition, progresses to be maximum size to occur at pair formation and when paired hump recedes, sometimes as fast as day, so I don't think it gives fish any advantage as energy reserve. In one study, when groups of male midas were kept without females in large tanks they developed enormous nuchal humps that persisted. I don't think it's a mechanical advantage but more like looking scary. Composition of Hump in African cichlids is slightly different than American cichlids, and more of permanent compared to American cichlids.
My references
https://digitalcommons.unl.edu/cgi/viewcontent.cgi...
https://www.sciencedirect.com/.../pii/0016648075901367
Two research papers I couldn't get as they lack public access are (but looked at abstract)
1. Does sexual selection account for the conspicuous head dimorphism in the Midas cichlid?
2. Hormonal control of the nuchal hump in the cichlid fish Cichlasoma citrinellum
