Which Farmed Fish Welfare Issues Does the Public Care Most About? (Activist Messaging)


When advocating for non-human animals, it helps to keep in mind that humans are often influenced to act when they perceive an individual as suffering. This fact is especially relevant to fish advocacy, since humans have a much harder time empathizing with fish than they do land animals.

It also leads us to ask these questions: Which farmed fish welfare issue is perceived as causing the most suffering? And which farmed fish welfare issue is most likely to prompt the public to demand change from major food companies? Answering these questions will allow farmed animal protection groups like Mercy For Animals to create more effective talking points and more persuasive materials (videos, websites, and so on) when advocating for policy improvements for farmed fish.


For this study, we recruited 215 participants from Amazon Mechanical Turk. We presented them with short descriptions of six major farmed fish welfare issues: crowding, slaughter, handling, feeding practices, breeding, and water quality. Each issue was described in two to three sentences in the persuasive style typically used by animal protection organizations. The six issues were presented to participants in a random order.

After reading about an issue, participants were asked three questions:
  1. To what extent do you think the issue you just read about causes pain and suffering to fish? (The response scale was from 0—fish don’t suffer at all—to 10—fish suffer greatly, much like humans.)
  2. If you found out that a restaurant that you eat at, such as Burger King or Red Lobster, served fish products (such as fish sandwiches or fish fillets) from fish who were raised in the condition you just learned about, would you want to stop eating at that restaurant?
  3. How important do you think it is for restaurant chains, such as Burger King or Red Lobster, to serve fish products (such as fish sandwiches and fish fillets) from fish who are not raised in the condition you just learned about?
Participants were also asked to force-rank the six welfare issues on how much suffering each issue caused.

We analyzed 203 completed responses using t-tests, with p-values adjusted using the Holm-Bonferroni method.


Which Practices Are Viewed as Causing the Most Suffering?

On a scale of 0 (fish don’t suffer at all from this) to 10 (fish suffer greatly from this), participants rated the six farmed fish welfare issues between 6.2 and 7.9.

Crowding, slaughter, and water quality were rated as causing the most suffering. These three issues were rated significantly higher than handling, feeding, and breeding, although the differences between these three and the others were not statistically significant.

It is worth noting that participants rated fish capacity for suffering fairly close to human capacity for suffering. We’re not confident that this is an accurate picture of how much participants think fish can suffer. In this subsequent study, fish were thought to have a significantly lower capacity for suffering than other farmed animals. Since we didn’t ask participants to rate any other animals in the current study, we don’t think that the absolute values should be used but that we should focus on values relative to one another to determine which welfare issues are thought to cause more suffering than others.

Would You Eat at Restaurants That Used These Practices?

On a scale of 0 (this practice would not make me at all less interested in eating at a restaurant) to 10 (this practice would definitely make me less interested in eating at a restaurant), ratings of each of the six issues ranged from 5.5 to 7.2.

Poor water quality (and its outcomes on fish welfare) was the issue that made people most likely to want to stop eating at a restaurant, and the difference between it and the other five welfare issues was statistically significant.

Should Corporate Policies Be Changed?

On a scale of 0 (it’s not at all important that companies prevent this practice in their supply chains) to 10 (it’s very important that companies prevent this practice in their supply chains), participants’ ratings for the six issues ranged from 5.9 to 7.4.

Poor water quality was the issue that participants felt most strongly restaurants should not allow in their supply chains. (This result was also statistically significant.) The second-most important issue participants wanted companies to address in their supply chains was crowding. Participants were least concerned about breeding. (The difference here was also statistically significant.)

Welfare Issues Ranked

After rating all the issues separately, participants were asked to rank the six welfare issues according to which issues they thought caused the most suffering.

Overwhelmingly, people ranked slaughter as causing the most suffering to fish. Just over half (52%) of participants put slaughter at the top of the list. The issues of water quality and crowding were also ranked high by participants—crowding was ranked first or second by about half of participants, and water quality was ranked in the top two by about 40% of participants.

Breeding was ranked last by nearly half of participants, and feeding was ranked last or next to last by about half of participants.


The results of this study suggest that poor water quality, along with the welfare issues it causes, is the farmed fish welfare issue that resonates most with the public. It is the issue that participants felt most needed to be addressed in a restaurant’s supply chain. And participants were most likely to stop eating at a restaurant if poor water quality existed in its supply chain.

Crowding and slaughter also appear to be issues that generate some concern from the public, with slaughter viewed as causing the most fish suffering. Poor breeding (and the welfare issues it causes) appears to be the issue least likely to generate public support for policy change.

These results suggest that farmed animal protection organizations working to create policy changes to protect farmed fish should focus primarily on poor water quality and its outcomes and secondarily on crowding and slaughter.

More research is needed, however, before drawing any final conclusions on this topic—in particular, research to see whether these results hold when participants are presented with more comprehensive information, such as a webpage or petition with pictures and text. Mercy For Animals intends to carry out such research in the coming months.


Below are the descriptions of animal welfare issues presented to study participants.

Tanks are so overcrowded that the fish are jammed so tightly together they can barely swim around and often don’t have enough oxygen to breathe. This causes fish to become so agitated and aggressive they sometimes bite off the tails and eyes of other fish.

Unlike some other farmed animals, they have no meaningful legal protections during slaughter. They are often killed by being chopped open while still alive and fully conscious. Others are left in open air or in ice slush to slowly and painfully suffocate to death, which can take anywhere from ten minutes to several hours.

Fish are often yanked out of the water for long periods of time (which causes them to start to suffocate), are swung by the tail, and are dropped or thrown onto hard objects. They are also often crowded tightly together by nets, and are sometimes maimed or killed by being jammed against sharp objects during the handling process.

Feeding Practices
The majority of wild-caught fish are actually caught and killed to be fed to factory farmed fish. Because of this, fish farms are a leading cause of overfishing and ocean depletion, as well as many of the other consequences of overfishing:  coral reef destruction, ocean acidification, and destruction of non-targeted species like dolphins and turtles.

Poor Breeding
Fish are artificially bred to grow as fast and as large as possible with no concern for how it impacts their welfare. As a result, these unnatural fish are often abnormally aggressive with one another and suffer health problems caused by their poor breeding.

Water Quality
The water quality in the tanks is often very bad, which causes a host of problems for fish, including infestations of parasitic sea lice, which eat away the flesh and faces of fish. Fish receive no individual veterinary attention, and the bad water quality leads many fish to slowly and agonizingly suffer to death from disease or other ailments.

Supporting Documents