Sentience
Dictionary definitions are a poor argument in themselves but are nevertheless useful in distinguishing the point of an argument. I haven’t completed my decision, but I think I’ll have to forego fishes as a dining option just the same. The idea posited among the comments on this site that fish are not sentient, that the pain it was recently determined they feel is non-conscious, seems incomplete. Sentience is not thought, but feeling, even if it is qualified as requiring perception, so pain is pain, and pain experienced beyond a certain limit is suffering. If God didn’t want us to eat the animals, he wouldn’t have made them delicious, right? That’s just despair. If humans are different than animals it is in the choices we make (shades of Jonathan Livingston Seagull), and we can elect to eat soybeans and little vitamin pills, or we can compromise and reduce suffering but still factory-farm, or we can join the red-in-tooth-and-claw crowd. What we cannot do and claim anything more than tool-maker status among the apes is to remain disconnected from our actions. St. Paul says we are to judge the angels and therefore are authorized under the laws of heaven to judge among ourselves, but I’m not really prepared to start handing down edicts. I’ll just forego the prawns, thanks.