**Background:** Nile tilapia (Oreochromis niloticus) is a major aquaculture species, and precise amino acid (AA) nutrition is critical for optimizing growth, health, reproduction, and fillet quality while minimizing environmental nitrogen loss. The last comprehensive AA requirement summary was the National Research Council (NRC) 2011 edition. Since then, many new studies have been published, but inconsistencies in recommendations persist due to differences in fish strain, size, basal diet composition, and statistical methods. This review consolidates data from 1988 onward to propose updated, stage-specific AA recommendations.
**Methods:** The authors reviewed studies that determined AA requirements for Nile tilapia, primarily using single-AA addition or deletion methods. Data were expressed on a dry-matter basis. Growth rate, feed conversion ratio, and protein retention efficiency were considered the most appropriate response variables. Simple means (± standard deviation) were calculated for each AA recommendation. The authors also computed stage-specific dietary AA recommendations (g/kg diet) based on previously established crude protein requirements for fry (460 g/kg), nursery/pre-growout (350 g/kg), and growout (320 g/kg) stages, and for broodstock at three protein levels (350, 380, and 400 g/kg). Ideal AA ratios relative to lysine were also derived. Statistical methods used in the reviewed studies included broken-line models (27% of recommendations), linear and broken-line (9%), polynomial regressions (50%), and the deletion method (14%).
**Key Results:**
- **Tissue AA composition:** Lysine was the dominant essential AA (mean 6.6 g/100 g crude protein across stages), and glutamic acid the dominant non-essential AA (mean 12.0 g/100 g crude protein).
- **Dietary AA recommendations (g/kg diet):** For growout stage (320 g/kg crude protein): Arg 16.3, His 7.7, Ile 12.2, Leu 13.4, Lys 18.2, Met 9.0, Met+Cys 10.9, Phe 10.9, Phe+Tyr 19.2, Thr 13.8, Trp 0.3, Val 11.2. For nursery/pre-growout (350 g/kg CP): Arg 17.9, His 8.4, Ile 13.3, Leu 14.7, Lys 20.0, Met 9.8, Met+Cys 11.9, Phe 11.9, Phe+Tyr 21.0, Thr 15.1, Trp 0.4, Val 12.3. For fry (460 g/kg CP): Arg 23.5, His 11.0, Ile 17.5, Leu 19.3, Lys 26.2, Met 12.9, Met+Cys 15.6, Phe 15.6, Phe+Tyr 27.6, Thr 19.8, Trp 0.5, Val 16.1.
- **Ideal AA ratios (% of lysine):** For growout: Arg 81, His 34, Ile 51, Leu 66, Met 41, Phe 70, Thr 89, Trp 23, Val 73. For nursery: Arg 86, His 30, Ile 56, Leu 84, Met 41, Phe 64, Thr 103, Trp 16, Val 60.
- **Key individual AA findings:** Lysine utilization efficiency was 63% in nursery/pre-growout and 48% in growout fish. Cystine could spare up to 49% of the methionine requirement on a molar sulfur basis. The optimal branched-chain AA ratio (Ile:Leu:Val) was 1:1.3:0.9 for pre-growout fish. Tyrosine replacement value for phenylalanine was 37% on a molar basis. Arginine at 23.9 g/kg diet improved immune responses and survival against Streptococcus agalactiae, but 41 g/kg promoted liver necrosis.
- **Non-essential AAs:** Glutamine, glycine, taurine, and carnitine were identified as conditionally essential or functional AAs with roles in growth, intestinal health, antioxidant capacity, lipid metabolism, and flesh quality.
**Clinical Implications:** The updated AA recommendations provide a more precise framework for formulating Nile tilapia diets across all production stages, including broodstock. Using the ideal protein concept with lysine as the reference AA simplifies diet formulation and supports cost-effective, low-nitrogen-excretion feeds. The review highlights that genetic improvements in tilapia have increased growth rates and fillet yields, likely raising AA requirements above NRC (2011) values. Future research should focus on AA interactions, digestible AA requirements, the role of non-essential AAs, and the application of genomic tools to refine recommendations further. Well-balanced AA diets are essential for improving both the economic and ecological sustainability of tilapia farming.