<p>ZBTB48 (also known as TZAP) is a transcription factor that has previously been reported to bind to telomeres and act as a negative regulator of telomere length in human cell lines. To explore whether transcription factor activity and telomere length regulation are conserved at the organismal level in vertebrates, we generate a <i>zbtb48</i>^{<i>−/−</i>} zebrafish line via CRISPR‒Cas genome editing. The <i>zbtb48</i>^{<i>−/−</i>} mutants display no obvious physical or behavioral abnormalities in the first two generations. We find no statistically significant changes in telomere length in first-generation adults. However, for the gene regulatory aspect of Zbtb48, similar to that in human cancer cell lines, we observe downregulation of <i>mtfp1</i> at both the mRNA and protein levels in the <i>zbtb48</i>^{<i>−/−</i>} mutants. This suggests that <i>mtfp1</i> is an evolutionarily conserved regulatory target of Zbtb48. Further investigation of the spatiotemporal expression of <i>zbtb48</i> in previously published zebrafish data reveals low transcript expression in diverse tissues, except in germline stem cells and gametocytes of the gonads. Notably, Mtfp1 protein downregulation is detected in the ovaries of 40 dpf <i>zbtb48</i>^{<i>−/−</i>} mutants and in the testes of both 40 dpf and 10.5-month-old <i>zbtb48</i>^{<i>−/−</i>} mutants.</p>