I am a vegetarian, and I disagree with this. I feel that it is more ethical to kill and eat an animal that has at least been given a chance to live a free and natural life, vs. confining it to a prison from birth.
Of course, it would be impossible to maintain humanity's current level of meat consumption without animal farms. I would prefer that people dramatically reduce their meat consumption, and eat only hunted/caught animals.
The level of intelligence I will eat, between chicken and fish, is totally arbitrary.
I think this is true for anyone who is not actually vegetarian.
The next level down is insects and oysters, I suppose.
Don't eat octopus because they are smart
Eat fishes, even those able to detect, hunt, defeat and eat octopus (therefore smarter than them)
After we left our hobby farm I decided to not eat anything smarter than a fish. (I don't eat octopus)
I like being Pescatarian.
I do try to avoid wild fish for ethical/environmental reasons. Food animals should always come from a farm, obviously.