The preset invention relates to a promoter to target a fluorescent protein to the muscles of fish, such as A. nigrofasciatus, for ornamental purposes, which is a Mlc3 (myosin, light polypeptide 3, skeletal muscle) promoter. The Mlc3 promoter has the nucleotides of tilapia (Oreochromis niloticus) myosin light chain 3 (Mlc3) promoter region, which is potential to be a tilapia Mlc3 promoter to enhance protein expression in muscle of fish, particularly for the generation of ornamental fish.