Always rather assumed it... When it is talked about in other languages though there are seperate words for 'the flesh of mammals' and 'fish'. 'Meat' in english is like... It's like how we don't have a gender neutral word for 'cow' or 'bull'. The closest thing there is is 'cattle'.
yeah, I understand the etymology behind it and it does make sense
Still, I make fun of the girl that used to work here that claims to still be vegetarian despite eating fish because fish != meat.