Though I don't keep Pelvicachromis pulcher (Kribensis or Rainbow Kribs), it's a popular cichlid in the hobby. There are several species of Pelvicachromis, and sometimes "Kribs" is used to label all of them. However, when most cichlid keepers refer to "Kribs" they mean the pulcher species.
Male and female Kribs are both very protective of their fry, and the parents are highly territorial. But apparently, that's not the only behavior that is reflective of the species. As it turns out, female Kribs are a bit predictable regarding their mate selection when given options.
If you only have a breeding pair of these beautiful little cichlids, then you won't be able to experience their mate selection process. But if you had a community of males and females, what might females be looking for in a mate?
A group of researchers at the University of Hamburg in Hamburg, Germany recently discovered that, given options of male boldness behavior (defined as "activity under simulated predation risk"), females may well exhibit a preference. Observing both level of boldness and degree of boldness consistency, the researchers concluded that females tend to favor males who exhibit boldness levels dissimilar to their own level but favor males that are similar in degree of consistency to their own. In other words, females with high levels of boldness tend to favor males with lower levels of boldness (and vice versa), but favor males with the same degree of boldness consistency as themselves. What does this mean? It means this mate selection pattern would be expected to occur more frequently than what would be expected versus a random mating pattern.
Scherer, U., M. Kuhnhardt, and W. Schuett. "Different or alike? Female rainbow kribs choose males of similar consistency and dissimilar level of boldness." Animal Behaviour 128 (2017): 117-124.
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