cleaner fish

Cleaner Fish Reduce Aggression in Captive Aquaria

Cleaner Fish Reduce Aggression in Captive Aquaria

Aggression among fish is a natural behavior. Competition for resources like food, territory, and suitable mates is literally a matter of life and death for many fish. This natural, even instinctual behavior can become exacerbated in the confines of captive aquaria (um…in your fish tank, for short). Aggression can escalate in an aquarium because of the limited space and mixture of species can cause unnatural interactions. Well, the good news here is that researchers from the University of Queensland may have found a solution to the problem–and the solution is cleaner fish.

cleaner wrasse
image by Silke Baron

According to the research, the presence of a cleaner fish species,  Labroides dimidiatus, reduced the amount of aggression in the captive aquariums studied. The Australian researchers measured how frequently predator fish chased prey fish in the captive aquaria in the investigation. What they found was that predators chased their prey two thirds less frequently in aquaria with cleaner fish than in aquaria without. If you think about it, that’s an astounding behavioral change. If the predator fish, on average, chased prey fish 10 times on an average day, it suggests that they would chase prey only ~3 times, simply because a cleaner fish was present.

The decrease in aggression appears to be tied to the cleaner fish’s behavior of touching the ‘client’ fish with their fins.  The Cleaner wrasse touched predator fish at least three times more than non-predator fish.  Also, the more often they touched their ‘clients’ with their fins, the more peaceful the tank was.

Neon Goby
Another cleaner fish species

The research does not claim to be a cure-all for aggression or to be a solution for mixing incompatible species.  It does, however, suggest that cleaner fish have a calming effect on the tank’s inhabitants.

Published in Aquarium Fish International: January 2009, page 18

Based on the following article

Please note, the image images to the left and below are of another cleaner fish species–the neon goby, one of my absolute favorite beginner fish. The study specifically looked at the Cleaner Wrasse, a fish with a notoriously dismal success record in the saltwater aquarium hobby, which is a fish that the average hobbyist should avoid. So if you intend to try and put the findings from this research to use in your own aquarium, I encourage you to try the neon goby instead. Before you do–take a few measurements of aggressive behavior for a week or two before and after you add the cleaner fish and leave a post here to let us know what YOU observe.

To learn more about reducing aggression in a saltwater tank, check out this article.

cleaner fish
Image by Greg Tee

Written by Albert B. Ulrich III, author of the Reef Aquarium Book Series.






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