Koigender is a xenogender that is strongly connected to koi fish, either identifying as such or incorporating their concept into one's gender to better understand it. This connection could be due to one's kintype, but the term is not exclusive to otherkin.
This gender can also feel calm and like a fish swimming peacefully in a pond. Another way one could experience this gender is in a connetion to the marble like texture of some Koi Fish, the gender feeling random and hard to grasp.
One who identifies as koigender may refer to themselves as "koigirl," "koiboy," or "koienby", depending on their other gender identity/identities.