fishillusionment
Explanation
The Joke
A scientist (wearing a lab coat) proudly explains to a visitor their method of "ethical animal consumption." The scientist describes raising a fish by showing it videos of heroic, law-abiding fish. Then, when the fish is mature, they show it those same heroic fish secretly collaborating with pescetarians (people who eat fish but not other meat). The result is that the fish becomes so disillusioned and cynical that it "feels nothing and longs for death."
The fish is shown in a tank looking utterly despondent, with blank, dead eyes. The caption at the bottom reads: "We discovered a new form of ethical animal consumption."
The Humor
The comic is a dark satire on the ethical debates surrounding meat consumption. Rather than solving the moral problem of killing animals for food by, say, improving living conditions or finding alternatives, the scientists take the absurd approach of psychologically torturing the fish into wanting to die. The joke is that this technically makes the consumption "ethical" because the animal consents to its own death -- but the method of achieving that consent is arguably far more cruel than simply catching and eating the fish normally.
It also parodies the way humans sometimes create elaborate ethical frameworks to justify their behavior while making the underlying situation worse. The concept of showing a fish propaganda videos about other fish collaborating with their predators is a wonderfully absurd twist on real-world disillusionment -- like finding out your heroes were corrupt all along.
References
Pescetarianism is a real dietary practice in which a person abstains from eating meat but continues to eat fish and other seafood. The ethical debate around pescetarianism often centers on whether fish experience suffering, which this comic takes to an absurd extreme by depicting a fish experiencing profound existential despair.