Paqr9 is a gene encoding membrane progestin receptor e (mPRe), the fifth subtype of the five mPR subtypes, and is currently classified a member of the progestin and adipoQ receptor (PAQR) family, which consists of 11 genes. To elucidate the physiological functions of the mPR subtypes, we established gene knockout (KO) fish via genome editing of seven paqr genes in zebrafish and analyzed their phenotypes. The null-mutant strain of paqr9 (paqr9