Effect of weight classes on body composition and processing yield of cultivated matrinxã (<em>Brycon cephalus</em>)

Abstract

Matrinxã is a native fish from the Amazon basin, which has been cultivated in the Southestern region due to increasing interest in sport fishing. Although there is no agreement on the ideal commercialization weight for the species, fishing has been carried out with fish above 600 g. This study aimed to determine the processing yield and body composition in three weight classes. Forty-five fish were collected in fish ponds at Caunesp, Jaboticabal, SP, according to the following weight classes: P₁ = 400 to 500 g; P₂ = 501 to 600 g; and P₃ = 601 to 700 g. The fish were filleted and their body composition was determined. The following yield parameters (%) were evaluated: skinless fillet, visceral fat, headless carcass, and total residue. For body composition, moisture (M), crude protein (CP), lipid (L), and ash (A) were determined. The weight had effect on (p < 0.05) the visceral components (V), and headless carcass (Cs/H); however, fillet yielding (F), visceral fat (VF), and residue (R) did not display significant difference (p > 0.05). The lowest value obtained for headless carcass and visceral components was observed for weight class P₁ (75,94% e 8,38%) and the highest for P₃ (78,05% e 9,48%). It should be noted that visceral fat is about 43% of total visceral components for all weight classes with significant and positive correlation (r² = 0.957*). The body composition showed significant differences with respect to ash: the highest value was found in the heaviest weight class. Although not significant, a tendency for higher fat accumulation in heavier fish was observed. The lipid content reflects a common feature in tropical fish species. From the analysis of the results, it is possible to conclude that crude protein and lipid were similar for all evaluated weight classes. Therefore, smaller fish may be processed while maintaining fillet yield.