DNA polymerase theta (Pol θ)is a conserved an A-family polymerase that plays an essential role in repairing double strand breaks, through micro-homology end joining, and bypassing DNA lesions, through translesion synthesis, to protect genome integrity. Despite its essential role in DNA repair, Pol θ is inherently error prone. Recently, Pol θ has been identified in various cancer types, suggesting Pol θ's promiscuous nature aids in cancer progression. Here we present a study comparing the structure and function of the polymerase domain of zebrafish and human Pol θ to determine the potential of zebrafish as a model for Pol θ function. We show that these two proteins share a large amount of sequence and structural homology, but differ in key loop areas thought to drive defining functions of the enzyme. Despite these differences zebrafish Pol θ still displays characteristics identify in human Pol θ, including DNA template extension, microhomology-mediated end joining, and translesion synthesis. Additionally, we found several important residues within loops of the polymerase domain that support function unique to Pol θ. These results will support future studies with zebrafish as a model to investigate Pol θ function.