Growth traits in largemouth bass (Micropterus salmoides) are crucial indicators of quality and yield. Thedevelopment of growth single nucleotide polymorphism (SNP) markers and exploration of dominant genotypesand growth genes will enhance our understanding of the genetic mechanisms underlying growth and development.Moreover, this research will facilitate the selection and breeding of new populations with exceptional growth traits.Using restriction site-associated DNA sequencing (RAD-seq), we conducted SNP screening in the F0 generation ofthe northern subspecies of largemouth bass, focusing on extreme groups with very high body weights (top 1%) andvery low body weights (bottom 1%). A general linear model (GLM) was applied to establish correlations betweenthe SNP genotypes and four growth traits (body weight, body length, body height, and body thickness) in a cohortof 230 F0 individuals. Additionally, candidate genes associated with growth were predicted using gene annotationinformation, and the combined additive effects of the dominant genotypes were analyzed through examination oftheir aggregation. A total of 4196486 high-quality SNPs were identified across 23 chromosomes of the largemouthbass. Using a population-specific genotype frequency threshold of 0.7, we initially screened 100 potential SNPloci related to growth and identified 12 that were significantly associated with growth. Specifically, five SNPswere significantly associated with body weight, 10 SNPs were significantly associated with body length, fourSNPs were significantly associated with body height, and five SNPs were significantly associated with bodythickness. Notably, the candidate growth genes fam174b, diaph2, kiaa1549lb, and ppip5k1b were linked to specificSNP markers including SNP19140160, SNP24406191, SNP3355498, and SNP9244620, respectively. Theenrichment of 6−10 dominant genotypes resulted in an average increase of 32.07% in body weight, 9.63% in bodylength, 9.96% in body height, and 10.58% in body thickness compared to the enrichment of 0–5 dominant genotypes,significantly improving the effect of genotype enrichment. The 12 fast-growth SNP markers and four candidategrowth genes identified in this study could assist in the improvement of growth traits in largemouth bass.