Being with the Wrong Partner Puts Fish in a Bad Mood: Study

No, this isn’t fake news–it is actual scientific research. The upshot:  It appears humans are not the only creatures to develop a bad mood when they are with the wrong mate.  A new scientific study suggests that it also happens to fish.  The study seems to indicate that fish pine for their desired partners, challenging the view that only humans form emotional attachments.

Study overview

Researchers performed a series of tests on convict cichlids — a species of small, monogamous fish native to Central America — to measure their mood and emotional attachment.
They allowed 33 female fish to choose a male mate and then monitored the behavior of the females when they were not paired with their preferred partner.
In a series of tests, researchers trained the fish to recognize and open boxes, distinguishable by their color and position in the tank: a “positive” box filled with a reward of food and an empty “negative” box. Biologists then presented the fish with a third “ambiguous” box and measured the reactions of the female fish before and after separation from their preferred partner.
Scientists found that the females who were paired with their preferred partner were quicker to investigate the ambiguous box, but if a female had been separated from her preferred mate, it affected her responsiveness to the task.
Study Results
The researchers found that the females who were denied their first choice adopted a more “pessimistic” outlook on life.  That is, females separated from their preferred partners showed a “pessimistic bias” — in other words, a bleaker outlook on life — when presented with a challenge.
Scientists also found that females paired with their preferred male “invested more in reproduction,” spawned earlier and spent more time attending their eggs.  (source)

More specifically, the study found that females paired with their non-preferred male had lower reproductive success than those paired with their preferred male. The researchers then tested objectively affective states in fishes. Females that were assigned their non-preferred partner exhibited pessimistic bias, which indicates a negative affective state. By contrast, females that were assigned their preferred partner did not exhibit changes in their affective state. The researchers conclude that the results highlight the fact that the influence of pair-bonding on affective states is not human-specific and can also be observed in non-human species.


Journal Reference:  Chloé Laubu, Philippe Louâpre, & François-Xavier Dechaume-Moncharmont, (2019).  Pair-bonding influences affective state in a monogamous fish species, Proceedings of the Royal Society, B,