A pike doesn't aggro you even after you punch it if it has an item in its mouth.

This issue is pretty vague. Can you elaborate?

righto, i'll record some videos after i get home from school

Yes, this is intentional as the Pike is considered eating the fish item when it has a fish item in its mouth.
Although, we always consider changing a feature if it feels awkward.

knew it, thanks

i'm pretty sure this is intended
After you punch a pike with a fish item in its mouth, the pikes completely ignores you, but if the pike has any other item, like bone meal, he'll go for you like usual.