Reference for Meilah 40:21

ביום הקזה עסקינן דלא אכיל איניש דגים

And it ha further been taught: One should not let blood after a meal of fish, fowl and salted meat! - Rather said R'Papa: We deal with a case where [the vow was made] at a time when his eyes were sore, when one does not eat fish.

Jastrow

Jastrow