みずうおじゃありませんでした
水魚じゃありませんでした
mizū o ja arimasendeshita

Noun
Desu Copula

The polite, past negative form of みずうお

1. Was not a water fish.; Was not like a fish in water.; Was not skilled/comfortable (in a situation).

Past/Perfective
Negative
Polite
Terminal Form
Usually Written in Kana