Summary A 20 week feeding with three dietary protein levels (40, 45 and 50%) and four dietary energy levels (18.5, 19.8, 22.1 and 22.4 MJ kg−1) by range (P/E) ratios of 17.86–26.85 mg protein kJ−1 was conducted to investigate optimum protein, energy and protein to energy (P/E) for final weight (FW), specific growth rate (SGR), feed conversion ratio (FCR), protein efficiency ratio (PER) and Hepatosomatic index (HSI) Acipenser persicus Fingerling (Average weight 10.26 ± 0.11). Study was carried out in 3 × 4 factorial design. Acipenser persicus Fingerlings reared in fiberglass tank (500 L water volume) and fed to apparent satiation fourth daily. At the end of the experimental period six fish were sampled randomly from each replicate, killed and were preserved at −20°C for body composition analysis and Hepatosomatic index. The same energy level, increase in dietary protein from 40 to 45% resulted in significant increases in the final weight (FW) and Increase in protein levels from 40 to 45 and 50% led to a significant increase in (PER) Protein efficiency ratio fishes (P < 0.05). At similar protein levels, increasing energy from 18.5 MJ kg−1 to higher levels (21.1 and 22.4 MJ kg−1) resulted in a significant increase in W2 and PER values and an improvement of FCR (P < 0.05). Highest FW belonged to fish fed diet 7 (45% protein and 21.1 MJ kg−1) followed by fish fed diet 8 (45% protein 22.4 MJ kg−1) and fish fed diet 4 (40% protein and 22.4 MJ kg−1). Increase in dietary energy level from 18.5 to 24.4 MJ kg−1 resulted a accumulation of lipid in carcass. The highest body lipid and protein showed in fishes fed diet 3 (40% protein and 22.1 MJ kg−1) and 4 (40% protein and 22.4 MJ kg−1). The present study showed that diets containing 40% protein and 20.1–25.9% lipid with a P/E ratio of 17.86 mg kJ, prepared from good quality ingredients can meet the dietary requirements of A. persicus fingerlings without leaving adverse effects on the biochemical composition of the body.