So what exactly is a “nuchal hump”? Ever see a cichlid (or other fish) with a pronounced hump on its forehead? That’s a nuchal hump. What’s its purpose? That depends on the species. Research has shown that the hump serves multiple purposes, some of which are specific to the genera or species. For the Lake Tanganyikan keepers out there, findings from a recent study in Ichthyological Research do not contradict prior studies that found that the hump on Cyphotilapia gibberosa helps the species identify conspecifics and their gender. Since both male and female gibberosa possess nuchal humps, this means that the shape and size of the hump actually serve as identification markers within the species. I find this interesting because most research on Cyphotilapia focuses on the frontosa species. There just isn’t as much out there on gibberosa. In fact, it’s quite new as an identified species, being formally named in 2003. If you’re new to cichlids, it’s probably difficult to distinguish gibberosa from frontosa. As the only two species in the Cyphotilapia genus, they are very similar and often mistaken for each other. For details on the distinguishing characteristics, see the paper by Tetsumi Takahashi and Kazuhiro Nakaya in Copeia (full citation below), the very article where gibberosa was formally described and named.
I’ve only kept one species of cichlid with a nuchal hump, Telmatochromis sp. “temporalis shell,” so I can’t speak about gibberosa or frontosa other than to point out they are larger cichlids and thus require large tanks. As I’ve stated many times, I don’t keep the brutes. I keep cichlids typically categorized as “dwarves.” Needless to say, cichlids with nuchal humps are very visually distinctive from other species. Frontosas are immensely popular in the cichlid hobby and, if they and gibberosa exhibit the same exciting behaviors that my Telmatochromis do, you’re in for a treat.
Citations: Takahashi, T. “Function of nuchal humps of a cichlid fish from Lake Tanganyika: inferences from morphological data.” Ichthyol Res (2018). https://doi.org/10.1007/s10228-018-0614-y
Takahashi, T. and Nakaya, K. “New Species of Cyphotilapia (Perciformes: Cichlidae) from Lake Tanganyika, Africa.” Copeia, vol. 2003, no. 4, 2003, pp. 824–832.