Study Reveals that Fishes Have Distinct Personalities – Research Update

Hello, Frank Indiviglio here.  Working with Brown Trout (Salmo trutta), researchers at the University of Gothenburg (Sweden) have confirmed what many fish-keepers have learned by experience – that fishes of the same species possess individual characteristics and distinct personalities.

Aquarium Fish with Personality

Aquarists learn early-on that individual fish react very quickly to changes in their environment, and that not all do so in the same manner.  Even the universal tendency of aquarium fishes to move towards the glass in anticipation of food when someone passes by is not usually shared by every tank inhabitant (this is actually a quite interesting bit of learned behavior – after all, fishes that rushed out to “greet” large beasts would not last long in the wild!). 

Many folks find the various Cichlids to be among the most “personable” fishes, and my own experience supports this.  Observing several breeding pairs of Firemouth and Convict Cichlids convinced me that different personalities were clearly being exhibited…a disturbance that would send one male into hiding would spur another to attack; a certain female might be easily distracted from her maternal duties, while no amount of food could temp another to stray far from the fry, and so on. 

Native fishes that I have collected were even more individualistic, especially as regards their adjustment to captive habitats and new foods…Pumpkinseed Sunfishes in particular constantly surprised me with their unique reactions and behaviors.

The Survival Value of a Personality

In a study recently published (December, 2010) in Sweden, researchers tested the reactions of wild-caught Brown Trout to novel objects and to changes in their environments.  Individual fishes of the same age and sex exhibited widely varying behaviors in each situation – the same stimulus could incite different degrees of aggression, exploration or avoidance behavior. 

The trout were also marked and released back into the wild, and studied there.  In most cases, individuals exhibiting “shy” behavior in the lab grew more quickly (in the wild) than did bolder fish.  The researchers believe that bold fish might fare well in bare, indoor aquariums because they would be first on the scene for food.  In their infinitely more complex native streams systems, shy fishes would be able to compete more favorably.  Changing environments and other pressures seem to insure that no one personality dominates, at least among Brown Trout.

Although the issue was not addressed, I can’t help but believe that the presence or absence of predators is also an important influence on which personality type dominates in a particular situation.

Observations in the Field

Observations that I’ve made of wild Electric Eels, and others’ studies of Archerfishes and Yellow Perches, have convinced me that learning abilities and personalities vary among fishes.  Please see the article below for some related stories, and to find out how to conduct learning/personality experiments with your own fishes.

Further Reading

Fish Intelligence: Home Experiments 

Minnows Learn to Trust Others

We’d love to hear about your experinces with the “personable” fish you’ve kept. Please write in with your questions and comments. 

 

Thanks, until next time,

Frank Indiviglio

Brown Trout image referenced from wikipedia and originally posted by Zouavman Le Zouave
Firemouth Cichlid image referenced from wikipedia and originally posted by Tomolyka