Do Fish Have a Personality?

Yes, Fish Have Complex Personalities

The study of animal personalities has become a hot topic in behavioral biology.

Bring up the possibility of fish personalities to people of a certain advertising age, and they’ll happily remind you that it was the unique character flaws of one Charlie the Tuna that kept him permanently off Starkist’s hook.

But after the laughs die down, some scientists are left asking earnest questions about fish and animal behavior and point to research suggesting that individual personality traits may not be entirely human property.

Do Fish Have Feelings?

For most pet owners, the question is a non-starter. Fido is a saint, Tabby is a snob, and Polly wants her cracker—now! Individuals all.

And most people are aware of the many “personality” studies done with primates.

However, some animal personality researchers take it further, observing meaningful and consistent individual differences in at least 60 other organisms, including hermit crabs, squirrels, sheep, spiders, and lizards. But are those differences in personality?

According to Alison Bell, an animal personality researcher at the University of Illinois, Urbana-Champagne, personality is simply a consistent individual difference in behavior. “If that’s the definition we want to use,” she asks, “Then why do we want to restrict ourselves to one kind of organism?”

What is the Personality of a Fish?

Bell’s fish tanks at the Urbana-Champagne laboratories are swirling with speculation about fish conduct. She and her team work with sticklebacks measuring, among other things, their reaction to a supposed predator. Researchers insert a replica of a pike and watch what each stickleback does.

Also Check Out →  Artiodactyla - Even Toed Mammals Facts

What they’ve found is that individual fish behave… well, individually. Some show aggression, others retreat—consistently. Other traits observed are boldness, shyness, curiosity, sociability, and activity level. And this individual behavior extends to other situations. For example, the fish that confronts the “predator” exhibits aggressive traits elsewhere, such as picking fights among his own group.

So why, ask researchers, does one individual hide when danger presents itself and another boldly goes about its business? And why do those who behave in one way repeat that behavior even when circumstances don’t warrant it?

The Animal Personality Puzzle

Most species will adapt behavior to the environment—say, if food sources drop, an animal may change its foraging strategy or frequency.

But what stumps animal behaviorists is that similar traits, like aggression, shyness, or risk-taking are found in dissimilar species, like fish and birds, but not in every member of the species. And members of the same species of the same age, size, and sex can show a wide diversity of behavior, even under similar circumstances.

In the wild world, a strong personality can be an evolutionary liability—that is, personality can lead to rigidity, and in the wild flexibility makes more sense. For example, some spiders are more aggressive in defending their territories, but this same aggression may drive them to kill and eat their own offspring.

Researchers at the Santa Fe Institute in New Mexico have been looking for an evolutionary basis for animal personalities. They think that those animals with a lot to lose, especially in terms of reproduction, will be more cautious than those with little to lose. These are the late bloomers, who first take time to survey the surroundings. Their still-to-be-realized stake in the future governs their prudent behavior in the present.

Also Check Out →  What do Crickets & Grasshoppers Eat?

The reckless and aggressive, meanwhile, will throw caution to the wind, reproduce early with nary a thought to the circumstances and live, in an animal kind of way, for the day. “It’s all a bit puzzling,” says Sander van Doorn of the Institute, “because a risky personality leads to risky behavior in many unrelated activities. A hawk that will torment smaller birds is also likely to challenge an eagle.”

In other words, having a certain animal personality can get you erased from the gene pool. Yet, it exists.

Animal Personality—Science or Fad?

The scientific camps seem to divide along the lines of the behavior that determines personality vs. personality predicts behavior. Human behaviorists and some old-school ecologists dismiss much of the personality research as a fad. Even some working in the animal behavior field hedge on calling individual characteristics “personality”—preferring neutral tags like “behavioral syndromes,” “temperament,” or “variability.”

Luc-Alain Giraldeau, a behavioral ecologist at the University of Québec at Montréal is one of the scientists who find that lacking theoretical models, the research offers no new insights for behavioral and evolutionary biology. “Animal personality does not have the foundations of the theory,” he says. “So when we find it, we don’t know exactly what we’ve learned about biology.”

The Evolutionary Driver Behind Personality

For researchers—believers and unbelievers—the question that ultimately needs to be answered is how such a range of differences might have evolved. And if these differences are maintained in a population, they must carry some adaptive value. What is it?

Heady stuff. And perhaps the only way to bring the two sides together is to replace the “person” in personality with a new scientific term… Animality? Zoonality?

One can only wonder what Charlie would make of the debate.


  • “Do Fish Have Personalities?” by Alla Katsnelson in The Scientist, Volume 24, Issue 3.
  • “Do Pets Really Have Personality?” by Lee Dye, ABC News online.
  • “Animals Have Personality,”

Leave a Comment