ABSTRACT Variable individual growth rate is a phenomenon observed in fish cohorts that influences the aquaculture performance and fish cohort ecological viability. Our aim was to compare gene expression patterns of key growth genes in zebrafish larvae with different growth rate. The body length of sibling zebrafish larvae at 6 days post hatching (dph) was measured. The larvae were reared to 20 dph and measured again. Two body-length groups were clearly observed: 4 mm (small larvae) and 5-6 mm (large larvae). Total RNA was isolated from both groups. Growth hormone (gh), growth hormone receptor (ghr), insulin-like growth factor 1 (igf-1), insulin-like growth factor receptor (igf-1r a/b), insulin-like growth factor binding protein 1 (igfbp-1), thyroglobulin (tg), cholecystokinin (cck), and ghrelin were evaluated by quantitative polymerase chain reaction (qPCR). Glucokinase (gck) and igfbp-1 were included as a gene expression marker of larvae nutritional status. Two genes showed significant differences between the body length groups, igfbp-1 (P = 0.01) and igf-1r (P = 0.02). The igfbp-1 suggests than growth rate variability was associated with the larvae nutritional status and this condition affect the gene expression pattern of igf-1r. Therefore these genes are interesting genes markers for growth rate variabilities studies.