Updated publication reference for PubMed record(s): 31856193. Skeletal muscle in fish presents a high plasticity controlled by a dynamic balance between anabolic and catabolic signaling pathways. Decreased food availability can inhibit muscle growth and trigger muscle catabolism pathways, thu promoting muscle atrophy. In contrast, anabolism may be favored during restoration of food supply, promoting the muscle growth. Considering this, we analyzed fast-twitch muscle of juvenile Piaractus mesopotamicus (pacu) submitted to a prolonged fasting (30 days) and refeeding (up to 30 days) using shotgun proteomics and gene expression analysis. The relative rate of weight and length increase, as well as the expression of mafbx and igf -1 genes, suggest that prolonged fasting caused muscle atrophy and that 30 days of refeeding led to partial compensatory growth. Shotgun proteomics analysis identified 99 proteins after fasting and 71 proteins after refeeding periods, of which 23 and 17 were differentially expressed after fasting and after 30 days of refeeding, respectively. Most of these differentially expressed proteins were related to cytoskeleton, muscle contraction and muscle metabolism. Among these, parvalbumin (PVALB), a calcium-binding protein and food allergen, was selected for further RT-qPCR analysis, which showed that pvalb mRNA was not changed after 30 days of fasting and 30 days of refeeding, but it was downregulated after 6h and 24h of refeeding. This suggests a post-transcriptional regulation of PVALB in fish muscle. In conclusion, our results suggest that muscle atrophy and partial compensatory growth caused by prolonged fasting and refeeding affected the muscle proteome and PVALB expression. Our results can contribute to the understanding of muscle anabolic and catabolic pathways in response to changes in food availability.