I think I understand you.

You probably don’t know me, and I probably don’t know you either, as this is an open letter addressed to those who answer “pescatarian”— or similar terms like “pescetarian” or “pesco-vegetarian — when asked about which diet they follow. I have never been a pescatarian myself, but I have met quite a few during my life, so I am familiar with the concept. I have spent many years noticing what people eat, and I have arrived at some conclusions. This is why I think I understand you.

Please allow me to prove it to you, but before that, I want to thank you for having rejected the consumption of flesh from terrestrial animals. I know that some pescatarians eat eggs or consume dairy, while others don’t, but all of them reject the flesh of pigs, cows, sheeps, horses, camels, chickens, ducks, geese, pheasants, ostriches, rabbits, guinea pigs, or any other terrestrial bird or mammal people have converted into “meat”, and this is a very good thing that should not be underestimated.

I am not quite sure if you also reject the flesh of reptiles (such as crocodiles) and amphibians (such as frogs), even if most are also terrestrial animals, as some are very aquatic, and it may be that your criteria to consume them are based on where they live. However, I am pretty sure you would reject the flesh of seals, dolphins, and whales too, so I don’t think you could simply be defined as a “vegetarian who consumes aquatic animals” — please forgive me if I am wrong about this.

I think I understand why you don’t consume the animals mentioned above, because I also reject food containing parts of them. You probably reject them for ethical, environmental, health, spiritual, or cultural reasons, right? Perhaps you started rejecting them for one of these, but then you added the other reasons too. If that is the case, we have this in common, as I started to reject the flesh of these animals for animal rights reasons, but now I have added all the other reasons too.

If you also reject eggs, dairy, and honey, we have this in common too, and I imagine that the reasons you chose for these rejections are very similar to those for rejecting flesh. In any event, saying “no, thanks” when offered some food is something that you and I probably do quite often, even in situations when it would be easier to accept it had we not been gifted with the morals that guide our behaviour. So, thank you for not caving to social pressure or convenience and for sticking to your values.

There is something, though, that you and I do quite differently. You consume the flesh of some animals, and I don’t. You consume the flesh of hagfishes, lampreys, elasmobranchs, chimaeras, lobe-finned fishes, ray-finned fishes (which belong, respectively, to the biological animal Classes Myxini, Hyperoartia, Elasmobranchii, Holocephali, Sarcopterygii, and Actinopterygii, collectively named “fishes” even if this is more a culinary term than a biological term), as well as aquatic molluscs (such as octopuses, squids, cuttlefishes, clams, mussels, and oysters), crustaceans (such as lobsters, crayfishes, prawns, shrimps, crabs, and barnacles), and perhaps also some sea urchins and other marine invertebrates which collectively are sometimes referred to as “seafood” — all of them members of the Animal Kingdom, and therefore “animals”.  

Because of this difference, the number of species of animals you consume and I don’t, is likely higher than the number of species of animals we both reject. This is quite something because, on the face of it, the fact that you do not apply the same values that make you reject the flesh of some animals across all animal species seems quite irrational. As I said earlier, I think I understand you, that’s why I don’t think it is irrational. I think it is misguided, but not irrational, and I think I understand why your rationale on this issue clashes with mine.

Here is what I think is going on: I think you don’t reject the fishes and aquatic invertebrates as food because either you think they are “inferior” animals who would not suffer when hurt or killed, or you think that they may suffer, but such suffering is inevitable because you need to consume them to be in good health. Am I right?

If so, allow me to address these two justifications, because I think I have something that may help you. I have some information I hope you will value, as you probably used it before to reject the consumption of other animals. I have some knowledge I hope you will appreciate, because if you didn’t, you would not be a pescatarian but a regular “meat-eater”. I have some insight I hope you will relate to, because it qualifies some of the assumptions that you have used to select who is edible and who is not edible to you, that is.

I have two identities that inform my opinion: I am, first, a scientist. I am, in particular, a zoologist who specialises in animal behaviour (also known as an ethologist), and I have been one for over 40 years. The second thing I am is an ethical vegan, and I have been one for over 20 years.

As a zoologist, I can now tell you that most of the authors of scientific papers you may have read that support the idea that fishes are not sentient beings and cannot feel pain are no longer alive, and they have been replaced by scientists who have revisited the issue and now concluded that they indeed feel pain and are as sentient as you and I. This has become a growing consensus among reputable biologists, zoologists, animal physiologists, animal psychologists, and ethologists. 

Most peer-reviewed studies now point to the conclusion that all those vertebrates under the umbrella term “fishes” suffer when hurt and killed, and many scientists, including me, go beyond that by saying they have “consciousness” like mammals and birds. As far as the aquatic invertebrates is concerned, the consensus that is being reached goes in the same direction regarding octopuses, squids, cuttlefishes, lobsters, crayfishes, prawns, shrimps, and crabs, and the only ones left where there is still debate and significant difference of opinion are clams, mussels, oysters, and barnacles (but, in my opinion, they are all sentient too). In other words, if you have been pescatarian for some time and use the “non-sentient justification”, then this one is no longer available to you for the majority of animals you eat, as the scientific consensus has shifted significantly. Don’t take my word for it, go and check it yourself, and you will see (look up the 2012 Cambridge Declaration on Consciousness and the 2024 New York Declaration on Consciousness).

The second pescatarian justification, the health one, comes from two directions: a very old-fashioned one that suggests that animal proteins are needed for a healthy life, and a more modern one that says humans need to include Omega-3 fatty acids in their diet to be healthy, and fishes are a very high source of them. Well, the existence of healthy vegans who have been vegan for decades, like me, outright disproves the first one, and science has already explained why vegans tend to be healthier, suffer less cardiovascular disease, diabetes, cancer and obesity — because they are better adapted to nourish their bodies from a plant-based diet rich in fibre, vitamins, and minerals than from the cholesterol and saturated fats rich animal-based diets (and the flesh of fishes and marine invertebrates still has the same unhealthy components as the flesh of cows, pigs, or chickens — although not necessarily in the same quantities). The second one, the Omega-3 one, is more interesting. It’s true we humans need to ingest it, and it’s true that fishes have lots of it, but the fishes get it by eating algae. Most vegans get it from the same source the fishes get it, supplementing their diets with Omega-3 acids taken directly from the same algae — I take such supplements in the form of satchels at a cheap cost of 30 pence per day (40 US cents). But this is the crucial thing: vegans get cheap, pure Omega-3 from their supplementation, but pescatarians get expensive Omega-3 from contaminated sources full of toxins and unwanted chemicals.

You see, Omega-3 in “seafood” comes from inside the flesh of fishes and aquatic invertebrates, but such flesh has been contaminated by all sorts of pollutants that we humans created and dumped into the water, where these animals live. Mercury, a very toxic element, is one of the most well-known — and toxic — examples of contaminants found in fishes, and pescatarians are the ones most exposed to such toxicity. I am sure that you will understand how this is possible, if you think about it: We create the pollutants and toxins in our industries, we dump them to the oceans or the rivers (which take them to the oceans), and these contaminate some small fishes swimming in them, who will be eaten by bigger fishes increasing the concentration of such toxins, who in turn will be eaten by bigger ones concentrating them even more (known as bioaccumulation), until they end up on the plate of pescatarians with the maximum concentrations. Vegans, on the other hand, will get their Omega-3 directly from algae grown in uncontaminated water — and will pay much less for it — so the “health excuse” no longer holds water — pun intended. 

And here is another piece of food for thought: as the contamination of waters keeps rising, the contamination of fishes keeps rising too, so, every year, pescatarians are at a higher risk of serious health problems (and, by the way, don’t think that such risk decreases if you eat farmed fishes, because the contamination in fish farms may be even higher due to the intensive ways the animals are raised).

I know, that’s a lot to think about, but let me add a piece of information that may be the “last straw” that would make you consider whether you should stop being a pescatarian and move toward a healthier and more ethical diet. Have you thought about how many more animal lives have been sacrificed to feed pescatarians compared with traditional meat-eaters? I made this calculation myself. When you use the average grams of animal flesh people consume in a year, and how many animals such flesh is equivalent to, you will find that an average pescatarian is responsible for about 1,400% more animal deaths than an average non-pescatarian meat-eater who only eats terrestrial animals (such as cows, pigs, chickens and lambs). Another way to put it is that an average pescatarian causes fifteen times more animal deaths than an average non-pescatarian meat-eater. If you are sceptical about this figure, make your own calculations (and you will most likely find that I chose very conservative estimates), but before that, just think about your plates. How many full animal bodies could you find in a steak dish a meat-eater would eat, compared with a paella “seafood” dish that you would eat? 

Fifteen times more animal deaths. That’s quite a lot. However, this number is not an accurate estimate. It is, in fact, an underestimation. This fact will explain why: between 10% and 40% of fishes caught worldwide are unintentionally caught and are partly thrown back into the sea, either dead or dying (this is known as bycatch). 

If the number of sentient lives lost for you is something that worries you, the question you may want to ask yourself is, “Is it worth it?” Now that you know these animals suffer for you to eat them, and when you eat them, not only do you not improve your health in relation to the health of an average vegan, but your health risk increases considerably, is it really worth it? Are the reasons you chose for being a pescatarian outdated and no longer valid, so now they have become excuses rather than justifications? 

I may be wrong, but I think I understand you. I think you chose your diet because you thought about it with the available information you had at the time, then you fell into the habit of following it without thinking too much about it anymore, and you stuck to it out of convenience and routine. That’s understandable. However, now you know more, and even if you think I may be trying to deceive you because I am a vegan with “an agenda”, nothing prevents you from looking at this issue by yourself, trying to see if you can “debunk” my claims. 

If you do, I hope you will change your diet in the right direction. After all, you became a pescatarian because you are a rational person, and for the same reason, you now may decide to become a vegan — joining the millions of vegans who live healthier and more ethical lives.

I hope you do, for everyone’s sake.

Best wishes.

Jordi Casamitjana

London, UK