The upstream open reading frame (uORF) as an important component of the 5′ untranslated region (5′-UTR) of eukaryotic genes, has attracted much attention in recent years due to its significant role in gene expression regulation. However, research on uORF in fish is relatively scarce at present. In this study, using CRISPR/Cas9 gene editing technology, we targeted and knocked out the uORF in the zebrafish growth hormone receptor gene (ghr) to explore the impact of uORF removal on ghr expression and zebrafish growth and development. By constructing a zebrafish model with a ghr-uORF deletion, we found that after knocking out the uORF, the mRNA and protein expression levels of the ghr gene increased, and the mutant zebrafish showed a growth advantage at the later stages of growth. In addition, the muscle tissue development of the mutant zebrafish also changed, with muscle fiber morphology becoming more circular and arrangement being tighter. These results indicate that uORF plays a suppressive role in regulating ghr gene expression, and knocking out uORF may promote the growth and muscle development of zebrafish. This study provides a new perspective for understanding the regulatory mechanism of uORF in animals and offers a new strategy for genetic improvement in fish.