&lt;!-- @page { margin: 2cm } --&gt; &lt;p class="western" align="justify"&gt;The performance of juvenile pacu, &lt;em&gt;Piaractus&lt;/em&gt; &lt;em&gt;mesopotamicus&lt;/em&gt;, held at three different stocking densities, 14, 28 and 42 fishes/ m³, and two levels of tanks water renovation, 1¹/2 and 3 h, with two replications, was tested in a 3 by 2 factorial design. A series of 12 concrete rectangular shaped tanks (4,0 m x 1,5 m x 0,8 m deep), installed outdoors was utilized. The result of this study suggests that stocking density has a marked effect on the growth of juvenile pacu. It was observed that an increase of treefold in density and decreased water flow were related to increased mortality.&lt;/p&gt; &lt;p class="western" align="justify"&gt;KEY-WORDS: &lt;em&gt;Piaractus&lt;/em&gt; &lt;em&gt;mesopotamicus&lt;/em&gt;; fish; stocking density; water flow.&lt;/p&gt;<br>&lt;!-- @page { margin: 2cm } --&gt; &lt;p class="western" align="justify"&gt;O desempenho produtivo de juvenis de pacu, &lt;em&gt;Piaractus&lt;/em&gt; &lt;em&gt;mesopotamicus&lt;/em&gt;, submetidos a três densidades de lotação, 14, 28 e 42 peixes / m³, e a duas taxas de renovação total da água dos tanques, 1 ¹/2 , 3 h, foi testado em um delineamento inteiramente casualizado, em esquema fatorial 3 x 2, com duas repetições. Utilizou-se uma série de 12 tanques de concreto (4,0 x 1,5 m x 0,8 m de profundidade), dispostos a céu aberto. Os resultados demonstraram que a densidade de lotação e a taxa de renovação da água influenciaram o desempenho produtivo do pacu. Observou-se que o aumento em três vezes da lotação e o decréscimo da renovação da água determinaram menores desempenhos produtivos.&lt;/p&gt; &lt;p class="western" align="justify"&gt;PALAVRAS-CHAVE: &lt;em&gt;Piaractus&lt;/em&gt; &lt;em&gt;mesopotamicus&lt;/em&gt;; sistema intensivo; lotação; vazão da água; pacu.&lt;/p&gt;

El presente ensayo se llevó a cabo con el objetivo de obtener tecnologías de cultivo no existentes actualmente en el país, para ser transferidas, oportunamente, a potenciales productores.

This study aimed to evaluate and compare the proximate composition and fatty acids (FA) profile of four fish species Piaractus mesopotamicus (PM), Colossoma macropomum (CM), Piaractus mesopotamicus X Colossoma macropomum (PC) and Piaractus brachypomus (PB). Fish fillets were analyzed for proximate composition, fatty acid profile, and nutritional quality indices. In general, PM and PB presented lower moisture content (73.75 ± 0.07 and 70.47 ± 0.16) and higher lipid content (4.34 ± 0.81 and 9.23 ± 1.16), respectively (p < 0.05). Although all species presented the same PUFA>MUFA>SFA pattern, PM and PB showed higher total n-3 FA values (mainly DHA and EPA), while CM had the lowest one (p < 0.05). Moreover, PM and PB exhibited superior nutritional quality indices, presenting the highest h/H ratio and the lowest IA and IT ratio (p < 0.05). A similar nutritional profile was observed for CM and PC. Therefore, PM and PB represent an excellent source of high-quality lipids, demonstrating that these freshwater fish species can be considered optimal for human consumption.