Top definition
mystery fish is another word for a gross vagina. Its any girl that has been around and possibly contracted an std. You have no clue where she has been or who she has been with, therefore she could be called "mystery fish"
"Dude, Amber has been around so much, im changing her name in my phone to mystery fish"
by hcmhcxmc March 09, 2008
Happy St. Patties Day!