まるさばじゃありませんでした
丸鯖じゃありませんでした
marusabajārimasendeshita

Noun
Desu Copula

The polite, past negative form of まるさば

1. It was not a round mackerel.; It wasn't a round mackerel.

Past/Perfective
Negative
Polite
Terminal Form
Usually Written in Kana