In mammal, interleukin 17 A and F is hallmark inflammatory cytokine that plays key roles in protection against infection and intestinal mucosal immunity. Especially, in gastrointestinal tract (GI), the induction of production of antimicrobial peptides (AMP) via Paneth cell is one of the most fundamental role of IL-17A and F to keep good condition of GI microbiome and health. However, in teleost, although mammalian IL-17A and -F homologs, referred to as IL-17A/F1-3 have been identified in several fish species, its function in intestine are poorly understood. So, in this study, to understanding the role of the IL-17A and F in the intestine of the teleost, we focus on the IL-17A/F1 and construct its mutant strain in Japanese medaka (Oryzias latipes) using the genome editing technology, CRISPER-CAS9 system and performed 16s metagenomic analysis for KO and WT gut microbiome comparison.