Purpose: To create a CYP gene mutant from D. magna as a model for xenobiotic metabolism study Methods: We performed RNA-seq of wildtype 12 days old D. magna to find out the basal expression level of CYP genes. We picked up 5 highest expressed CYP genes and examined the temporal expression level from day 0 to day 12 by qPCR. We chose the highest expressed gene and performed mutagenesis to this gene by CRISPR/Cas9 to creat a mutant line. Results: From RNA-seq result, we found that CYP360A8 is the highest expressed CYP in D. magna. qPCR result showed that CYP360A8 has developmental pattern where its expression is low in juvenile, increase 6 fold by maturation time and stay stable till day 12. Mutagenesis experiment of this gene resulted in the obtaning of a monoallelic mutant. Paraquat exposure to this mutant line showed more sensitivity of the mutant compared to wildtype (showed by 1.3 fold lower of EC50). Conclusions: Our study showed the first mutant model of CYP in D. magna. This may be the start of creating a panel that list D. magna CYP gene with its inducing xenobiotics. Overall design: mRNA profiles of 12 days old wild type D. magna