I really like the quote about cod but I'm not particularly inspired by the moral given for the story. I'd prefer "I eliminated a non-terminal ethical principal when I realised my thinking was pretentious bullshit, moving towards a more coherent ethical framework. Yay me!"
I noticed that too; of course not eating fish is an ethical non-issue given how much other low-hanging consequentialist fruit there is.
However, note that his justification for his change of heart is pure rationalization. Whatever good reasons there might be for eating fish, or for abandoning vegetarianism, "they eat each other" is a bad one, a confabulation.
Fish and other animals are not capable of reflecting ethically on their actions, so they are ethically blameless for whatever they do. That does not mean their suffering doesn't count. Franklin knew that.
This is our monthly thread for collecting these little gems and pearls of wisdom, rationality-related quotes you've seen recently, or had stored in your quotesfile for ages, and which might be handy to link to in one of our discussions.