Fish Also React to the “Love Drug”

Written by on October 11, 2012 in Marine Life
Neolamprologus pulcher. Photo credit: Guérin Nicolas.

Neolamprologus pulcher. Photo credit: Guérin Nicolas.

Researchers are now a big step closer to determining why some species live solitary life styles while others develop complex social relationships.

Oxytocin, the “love drug”, is the hormone that plays a role in making humans fall in love.  Researchers have discovered that this same hormone (called isotocin in fish) plays a similar role in fish.

“We know how this hormone affects humans,” explained Adam Reddon, lead researcher from McMaster University.  “It is related to love, monogamy, even risky behaviour, but much less is known about its effects on fish.”

Reddon and his research team studied the cichlid fish Neolamprologus pulcher, an unusual species that forms permanent hierarchical social groups.  Each group has a dominant breeding pair with many helpers to look after young and defend territory.

They injected some fish with isotocin and some with a plain saline solution.  The fish injected with isotocin were more aggressive when placed in a territorial competition with a single other fish and were more submissive when confronted by more aggressive fish in groups.

“The hormone increases responsiveness to social information and may act as an important social glue,” says Reddon.  “It ensures the fish handle conflict well and remain a cohesive group because they will have shorter, less costly fights.”

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Copyright © 2012 by Marine Science Today, a publication of Marine Science Today LLC.

About the Author

About the Author: Emily Tripp is the Publisher and Editor of She holds marine science and biology degrees from the University of Miami's Rosenstiel School of Marine and Atmospheric Science and a Master of Advanced Studies degree in Marine Biodiversity and Conservation from Scripps Institution of Oceanography. When she's not writing about marine science, she's probably running around outside or playing with her dog. .


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