Positive Welfare For Fishes

Fish are often left out of animal welfare considerations, and many people fail to see them for the thinking, feeling beings that they are. Despite lacking facial expressions that we can decipher, or vocalizations that humans can easily understand, “fish” are incredibly complex range of species, with the ability to feel pain, fear, and stress. Not only are they able to feel these negative emotions, but they can likely feel joy, happiness, and playfulness as well. These positive emotions are often left out of animal welfare guidelines, which usually focus more on the absence of harm than the presence of pleasure.

In this study, researchers from New York University give an overview of the history behind positive welfare theory and expand on how it could be applied to captive fishes. Positive welfare, put simply, is the idea that the absence of harm only guarantees a neutral welfare state, and animals must have the ability to perform certain behaviors that are beneficial for their mental and physical well-being for their lives to truly be considered “good.” The freedom to play, socialize, and explore is essential to most animals’ welfare, including humans. Human psychology has recognized this for many years, but animal welfare guidelines still primarily focus on alleviating suffering and reducing physical signs of stress.

There are three motivational factors that the authors believe to be important in the promotion of positive emotional states. First, the motivation for value effectiveness, which is simply the drive to have or avoid certain material outcomes. With regards to positive psychology in fish, research could determine which food sources and habitats certain fish species most prefer. The motivation for control effectiveness is essentially a desire for agency – the ability to have control over one’s own life, to an extent. There is no research relating to this motivation in fish specifically. One study shows that Nile tilapia are less stressed when given control over their own feeding schedules, but more research is needed. The final motivation discussed is that of “truth effectiveness” – the desire to learn, explore, and engage in intellectual stimulation. Again, there is little research done in this field relating to fish, but the authors note there is some anecdotal evidence of fishes’ curiosity. They also note that, while many animals will observe and explore novel things in the right circumstances, unfamiliarity can also cause stress. To prevent this, the authors recommend stimulating environments that closely mimic the fish’s natural habitat.

Further to the above, positive well-being is correlated with several physical signs, which the researchers review. Physiologically, neurotransmitters like dopamine and endogenous opioids are associated with positive emotional states in most animals, as are well-functioning immune systems. Fish possess the necessary brain chemistry for these physiological states, and therefore are likely able to feel positive emotions as well as pain and stress.

Behaviors such as communication, socialization, and play are also important indicators of positive mental health. Many fishes, especially schooling species, are quite social animals, and the researchers list studies that provide some evidence that fish are capable of play. Some examples include: cichlids, observed to chase each other in a non-threatening way and nip at their parents’ sides; great white sharks, observed hunting when not hungry, possibly for fun; Atlantic salmon, whose jumping behavior has been hypothesized to be a form of locomotor play – similar to exercise in humans.

Play is one of the most important behaviors in captive animals due to its correlation with welfare states. When animals are happy and healthy, play behaviors are much more common. In situations where animals are stressed, crowded, or unhealthy, play behaviors decrease or disappear. Therefore, facilitating play behaviors in captive fishes is extremely important; lack of play provides an easily-observable sign of poor mental or physical health.

The authors of this review are unsatisfied with the current state of research regarding positive welfare in captive fish, and urge more scientists to explore the topic. However, they are still able to offer some suggestions, the most important of which is the creation of environments that closely mimic fishes’ natural habitats and provide opportunities for socialization and play. Captive fish, especially those used for food, are often kept in completely unsuitable environments for positive emotional states, and future animal welfare guidelines should ensure that all captive animals, including fish, are given the opportunity to live good lives. Considering the stunning scale at which fish are killed for food, animal advocates should follow developments in this field closely.