First of all , English is not my mother tongue and i have a question about poetry
i know it is a stupid question but is it necessary to use a fixed metric system in poet ?
sorry for my bad english
No, it is not.
There are a lot of English-language poems that do not use metre.
For example, Marianne Moore made a poem called "Poetry".
It is not consistent.
Many people associate poetry with the use of metre, though.
I hope that helps!