Although no symptoms of infection or outbreaks were observed in rag1−/− zebrafish that may explain the upregulation of antiviral and pro‐inflammatory genes, bacterial load was assayed as the transcript level of 16S rRNA in wt and rag1−/− control samples (total visceral mass in 4‐month‐old fish) by qPCR using universal bacterial primers. Here, RAG1 is linked to infection.