Ten-eleven Translocation (TET) enzymes catalyse the active removal of DNA methylation through the iterative oxidation of 5-methylcytosine (5mC) into 5-hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC) and 5-carboxylcytosine (5caC). While proper 5mC patterning is important for embryogenesis and differentiation, and is often dysregulated during disease formation, very little is known regarding the precise mechanisms of 5mC removal. In this study we aim to identify and characterize novel components implicated in 5mC removal pathways by using CRISPR/Cas9 genome editing and reduced representation bisulfite sequencing (RRBS) technologies. We have generated F0 CRISPR zebrafish embryos for dozens of genes and have studied their effects on embryonic development and DNA methylation by phenotypic observation and by investigating 5mC dynamics at a subset of enhancers known to undergo active demethylation. Several knockouts display developmental defects ranging from impaired intestinal development, heart edema, curved tails to head and eye malformations similar to those observed in TET1/2/3 triple knockouts. F0 mutants for Poly (ADP-ribose) polymerases and for an RNA Binding Motif Protein have so far been found to display increased 5mC at a subset of the aforementioned enhancers. By using CRISPR/Cas9 and RRBS technologies we have identified a number of genes involved in zebrafish embryonic development and with potential roles in active DNA demethylation.