hi hello, spicy take of the day:

"pescatarians" eat meat, fish muscle is meat. it's animal flesh.

if you insist on trying to hang with the vegetarians just because you only eat aquatic flesh and not mammal flesh it's because fish and crustaceans gross you out a little, sort of the way bugs and worms gross you out, so you consider them a moral exception for aesthetic reasons.

similar rationale as to why people always want to save the bees but not the wasps. bumblebees seem cuter and pollinate pretty flowers and fruits. wasps seem like vindictive jerks that just build grey papery nests or mud caves.

it's an emotional/aesthetic decision trying to disguise itself as an ethical one