Identifying potential patterns in pirarucu (Arapaima gigas) composition, as a function of the different fish muscle zones (dorse, venter, ventrecha and tail), was the main objective of this research. For such, the different pirarucu muscle zones were evaluated, in order to obtain proximate composition and minerals content. It was also determined amino acids and fatty acids contents in fish muscle. The dorsal, ventral and tail muscle zones presented similar moisture (76.5-78.2%), protein (17.8-18.9%), total lipids (1.0-1.5%) and ash (0.9-1.2%) contents. On the other hand, the ventrecha zone presented 25.8% of protein and the major total lipids content (17.1%). The main minerals found in fish muscle were K (183.5-288.6 mg/100 g muscle) and Na (65.1-175.5 mg/100 g). Glutamic acid (3027.6 mg/100 g muscle) was the main amino acid found in fish muscle, which presented 48% of essential amino acids in the protein fraction. Lipids content showed 57.3% of unsaturated fatty acids and 42.7% of saturated fatty acids.