Can fish feel pleasure? Scientists say yes, and they might even crave it
The Surprising World of Fish Pleasure: Can Fish Really Feel Joy?
When you think of a creature enjoying life to the fullest, a fish might not be the first image that pops into your head. However, recent research is challenging this perception by suggesting that some fish not only seek out pleasurable experiences but may even remember and crave them.
Marta Soares, a behavioural physiologist at the University of Porto in Portugal, explains that historically, fish research has focused on their stress levels. But in a study published in Proceedings of the Royal Society B, Soares and her team delved into a different aspect of fish behavior: can fish feel good?
Their study focused on mutualisms, interactions between species that benefit both parties. One fascinating example is the relationship between the bluestreak cleaner wrasse and the threadfin butterflyfish in coral reefs. The cleaner wrasse feeds on parasites on the butterflyfish’s skin, providing a free grooming session in return.
The researchers wanted to determine if these interactions went beyond hygiene and actually elicited positive feelings in the fish. They found that butterflyfish preferred to hang out in areas where they had interacted with cleaner wrasses, suggesting a positive memory associated with the experience.
Further experiments using opioid mimics and blockers revealed that fish have an opioid system in their brains that regulates pleasure. When given a morphine-like drug that stimulates pleasure receptors, the fish showed increased attraction to the cleaning area. Conversely, blocking opioid receptors with naloxone resulted in a loss of interest in the cleaning zone.
The team also explored whether fish simply liked the cleaning or actively wanted it. By introducing obstacles in the tank, they found that the fish were willing to navigate barriers to reach the cleaners, regardless of the presence of opioid mimics or blockers.
While some scientists remain cautious about interpreting these findings as evidence of fish experiencing pleasure, the study’s implications are significant. Understanding that fish can change their behavior in response to positive experiences could lead to improved treatment of fish in aquaculture and aquariums.
Ultimately, this research challenges the traditional view of fish as unfeeling creatures and highlights the complexity and flexibility of fish behavior. As we continue to uncover the intricacies of the underwater world, it’s clear that fish may be more similar to mammals like dogs and primates than we once thought.
