WNK2 and infection: <h4>Introduction</h4>Mitogen-activated protein kinases (MAPKs) are central to stress and innate immune signaling in fish, but their genomic composition and infection related transcriptional responses remain unclear in bighead carp (Hypophthalmichthys nobilis).<h4>Methods</h4>We performed a comparative genomic survey across 24 species and characterized MAPK family members in bighead carp based on conserved motifs, gene structure, and synteny.