Carcass Yield and Morphometric Characteristics of Semi-Intensive Pond-Cultured Piaractus brachypomus (Paco) at Three Commercial Weight Ranges in the Central Jungle of Peru

The expansion of tropical aquaculture in the Peruvian Amazon has increased the need for quantitative information on processing performance and morphometric variation in commercially important native fish species. This study evaluated carcass yield, morphometric characteristics, intestinal traits, and edible tissue recovery of Piaractus brachypomus across three commercial weight categories (251–350 g, 351–450 g, and 451–550 g) in the central jungle of Peru. A total of 75 specimens were collected from a semi-intensive earthen-pond aquaculture unit at the Satipo station of the Tropical Animal Science Program, Universidad Nacional del Centro del Perú, located in Río Negro District, Satipo Province, Junín region, and analyzed under a completely randomized design with 25 fish per category. External morphometric measurements, intestinal variables, and processing yield indicators were recorded and analyzed using analysis of variance, regression models, principal component analysis, and Pearson correlation analysis. Most morphometric variables increased significantly with body weight, whereas tail length remained stable among categories. Principal component analysis explained 80.8% of total morphometric variation and showed clear separation among commercial weight groups. Intestinal length and relative intestinal ratios also increased progressively with fish size. Carcass yield exhibited a moderate decrease with increasing body weight, concomitant with a substantial increase in edible tissue recovery in larger fish. Fresh body weight showed a strong positive relationship with edible tissue recovery and emerged as the main predictor in multiple regression models. These results indicate that commercial weight influences body conformation, digestive development, and processing performance in P. brachypomus, providing information that may support harvest optimization and processing management in tropical aquaculture systems.