The Slender Sunfish (Ranzania laevis) is circumglobal in tropical and warm temperate seas, including the Mediterranean, Sea of Marmara, and Persian Gulf. In Australia, it ranges from Lizard Island, Queensland, around southern Australia, to North West Cape, Western Australia. This assembly is based on PacBio HiFi long reads, Dovetail Omni-C libraries and Illumina short reads. Data was generated at the Minderoo OceanOmics Centre at the University of Western Australia and assembled in house using a custom pipeline (https://github.com/MinderooFoundation) that follows Vertebrate Genomes Project workflows (https://vertebrategenomesproject.org/). The raw data and version 1 assembly are made available and should be credited in accordance with Ocean Genomes data use and sharing policies URL: https://www.minderoo.org/oceanomics. To discuss interim access, please contact oceangenomes@uwa.edu.au.