A few weeks ago, I was searching for a scholarly article on something cichlid related and stumbled upon some interesting research on convict cichlids. I downloaded the paper and read it. I then looked up the authors and discovered that they regularly use cichlids in their research. I reached out to them about doing an interview for the blog and, thankfully, they agreed.
Professor François-Xavier Dechaume-Moncharmont is a behavioral ecologist who teaches at the University of Lyon in Lyon, France. His research focus is the evolution of decision making, within a sexual context, of fish.
Dr. Chloé Laubu is a former student of Dr. Dechaume-Moncharmont, and her research focuses on mood and personality of convict cichlids in a sexual context. Dr. Laubu works in the Laboratoire Biogéosciences at the University of Burgundy. The two researchers have authored several papers together, and their research is quite complementary.
With the introductions out of the way, let’s get started.
Talk a bit about your research as mentor and mentee.
During her research project in my lab, Chloé was interested in the most important, exciting, and difficult question in the world: how to find your soulmate? This is particularly challenging not only in our species, but also in most animal species, particularly those involving long-lasting pair bonds between partners and bi-parental care of the young. Our model species to explore this question is a tiny freshwater fish, the convict cichlid (Amatitlania siquia), which lives in some volcanic lakes of Nicaragua. The female and the male form stable pairs for several reproductive events – they collectively defend a territory, build a nest, take care of the eggs, attend the fry, and protect the young against predators during their foraging trips in the morning. It’s an exhausting task that requires both excellent coordination and commitment. Chloé’s project was to investigate two aspects of the relationship between convict cichlid partners as described in the next two questions.
Much of your research focuses on mating behaviors of convict cichlids. In fact, your paper (see Laubu et al., 2016 in references at the end) from a few years ago, co-authored with two others, titled “Mismatched partners that achieve postpairing behavioral similarity improve their reproductive success” is quite interesting. Can you summarize the findings of that effort?
In this paper, we considered the compatibility between partners in terms of personality. When ethologists speak about personality, it is not a naive anthropomorphic view of the animal. Personality can be rigorously and objectively characterized using standardized behavioural protocols assessing the activity, neophobia (fear of novelty), exploration, sociality and aggressiveness.
Our initial project was to assess the reproductive success of pairs of fish either matched of mismatched for their personality score. Very early during the analysis of the data, Chloé brilliantly identified an unexpected result. The mismatched pairs (pairs we have experimentally formed with fish of opposite personality) tend to look alike. We also observed that behavioural convergence was beneficial for partners. Converging pairs had better reproductive success (raised more young) than mismatched partners that did not converge. This behavioural convergence between partners has never been observed in any other (non-human) species.
More recently, you both co-authored another paper (see Laubu et al., 2019), along with Dr. Philippe Louâpre, which examined something a little different about convict pairing, but nonetheless interesting. In “Pair-bonding influences affective state in a monogamous fish species,” female convicts were actually trained to move an object. Can one of you describe this research for the readers?
In this paper we investigated a slightly different question. Chloé was interested in the adaptive value of emotion. We wanted to assess the existence of an emotional bond between partners. Here, the challenge was to develop an experimental procedure to objectively assess the emotional state in fish. One could not just make them verbalize their inner feelings.
Chloé had another brilliant idea. She transposed a psychological test classically used in humans, the judgment bias test, in which the experimenter compares the response of an individual to an ambiguous cue to the response to either a positive or a negative cue. If the response of the individual to the ambiguous cue is close to the response to the negative cue, it is interpreted as a pessimistic state of mind. Chloé succeeded to do that by teaching fish to open boxes covered by a colored lid (don’t miss the video illustrating this behaviour). The fish quickly learned to recognize the color of the positive box (containing a food item) from the negative one (no food reward). It was thus possible to assess the emotional state of mind (pessimistic or optimistic) of the fish by recording her reaction to an ambiguous box covered by a lid of intermediate color.
We then divided our females into two groups. Some females were paired with their most preferred partner, whereas for the others the preferred males were removed, and they stayed in the company of a less preferred male. In the latter group, we observed a pessimistic response to the judgment bias test. The absence of the loved one makes the female fish feel pessimistic.
Among the external factors influencing affective states, have you been able to determine if one is more influential than another with respect to positive valence (e.g., food quality versus water quality)?
We don’t know yet, but we are working hard to find factors that improve the mood in our fish, not only for animal welfare purposes (it is crucial to rear happy animals when you are studying their natural behaviour), but also we would like to experimentally elicit positive affective states in future tests. We are convinced that, as in most animal species, enrichment (e.g., presence of toys, complex habitat to explore) has highly a positive effect on the fish mood (See Höjesjö et al., 2004; Zidar et al., 2018; McCoy et al., 2019). Do fish actually play? Some researchers think so (See Burghardt, 2006).
What else might we be able to learn about affective states in cichlids that you did not hypothesize in the 2019 paper?
There is so much to explore. For instance, we don’t know for how long the emotional state lasts. Is it a very short-term state (few hours) or does it last for weeks? We don’t know if this positive state observed in a sexual context is able to bias other decisions. We are expecting that the rose-coloured glasses effect should be general in many contexts (e.g., mate choice, parental care, feeding, exploration, tolerance to danger).
Based on your experiments with convicts, have you been able to identity a single characteristic of males that makes them most attractive to females (in general)?
Here, I am convinced that body size is a major cue used by the female to find a partner. In a previous paper (See Dechaume-Moncharmont et al., 2013), we have shown that she is not looking for the biggest male in the tank but a male of matching size (30% larger than herself). A too large male is potentially dangerous in case of intra-pair conflicts and a too small male is unable to defend the nest against intruders.
Have you considered experimenting with other monogamous cichlid species besides convicts, perhaps to compare/contrast to your work with the convict cichlid? If so, please talk a bit about that.
Yes, we would like to work on emotion in other species. We are currently discussing with colleagues working with African cichlids in order to adapt our protocol in those species, but it’s too early to know if this attempt will work. Animal behaviour studies are generally long-term experiments. We will have to be patient, here.
It would be also relevant to transpose our protocol in other monogamous species that are more genetically distant from convict cichlids (some birds, rodents or primates for instance) to compare if there is also an emotional bond between partners in other species with similar pairing situations.
For hobbyists who keep convict cichlids, are there any behavioral patterns that you have observed which serve, or might serve, as clues to whether the hobbyist has a compatible or incompatible breeding pair? If so, can you describe these?
We generally allow an individual to choose a partner among several ones. It is straightforward to assess its preference in terms of display and spatial avoidance. In the convict cichlid, agonistic displays are easy to spot. A fish quickly becoming darker also indicates a high level of aggressiveness.
Please talk a little about what’s next for your cichlid research.
There is so much we don’t know about fish’s inner life. Most of us still consider that fish have very weak cognitive skills (the infamous 3-min window memory), whereas we are accumulating evidences about their impressive memory, spatial orientation skills, complex decision rules, etc. For instance, fish are capable of transitive inferences (See Grosenick et al., 2007), one of the components of rational thinking not always mastered by the humans.
As I said previously, we are trying to enlarge our understanding of the emotional states in our species (e.g., duration of the emotional state, existence of emotional contagion). I would also like explore the underlying mechanisms, particularly the role of hormones.
For some interesting video of behaviors described in the interview, visit the University of Burgundy’s cichlid team YouTube channel.
Balcombe, J. (2016). What a fish knows: the inner lives of our underwater cousins. New-York, USA: Farrar, Straus and Giroux.
Burghardt, G. M. (2006). The genesis of animal play: testing the limits. Cambridge, USA: MIT Press. Retrieved from http://www.worldcat.org/isbn/0262524694.
Dechaume-Moncharmont, F.-X., Freychet, M., Motreuil, S., & Cézilly, F. (2013). Female mate choice in convict cichlids is transitive and consistent with a self-referent directional preference. Frontiers in Zoology, 10(1), 69. doi:10.1186/1742-9994-10-69.
Grosenick, L., Clement, T. S., & Fernald, R. D. (2007). Fish can infer social rank by observation alone. Nature, 445(7126), 429–432. doi:10.1038/nature05511.
Höjesjö, J., Johnsson, J., & Bohlin, T. (2004). Habitat complexity reduces the growth of aggressive and dominant brown trout (Salmo trutta) relative to subordinates. Behavioral Ecology and Sociobiology, 56(3), 286–289. doi:10.1007/s00265-004-0784-7.
Laubu, C., Dechaume-Moncharmont, F.-X., Motreuil, S., Schweitzer, C. (2016) Mismatched partners that achieve postpairing behavioral similarity improve their reproductive success. Science Advances, 2(3). doi:10.1126/sciadv.1501013.
Laubu, C., Louâpre, P., Dechaume-Moncharmont, F.-X. (2019). Pair-bonding influences affective state in a monogamous fish species. Royal Society Proceedings B., 286. doi:10.1098/rspb.2019.0760.
McCoy, D. E., Schiestl, M., Neilands, P., Hassall, R., Gray, R. D., & Taylor, A. H. (2019). New caledonian crows behave optimistically after using tools. Current Biology, S0960982219308401. doi:10.1016/j.cub.2019.06.080.
Zidar, J., Campderrich, I., Jansson, E., Wichman, A., Winberg, S., Keeling, L., & Løvlie, H. (2018). Environmental complexity buffers against stress-induced negative judgement bias in female chickens. Scientific Reports, 8(1), 5404. doi:10.1038/s41598-018-23545-6.