What does fich which mean?

"Fich which" is not a common phrase in English. It's possible you've misheard or misspelled the phrase.

Could you be thinking of:

* "Which" - a question word used to ask for specific information.

* "Which one" - used to request a specific item from a selection.

* "Fish which" - perhaps you meant to say "fish which", referring to a specific type of fish.

Please provide more context or a complete sentence so I can better understand your question.