A new approach for quantifying phosphorus requirement in an Amazonian fish using CT-scanning

Phosphorus (P) is an essential mineral for fish growth, as it plays pivotal roles in skeletal development and energy transfer reactions. However, the dietary requirement of this mineral is variable among fish species and the growth stages. Thus, this study aimed to determine the digestible P (dP) requirement for tambaqui in the initial growth stage (±17 to 150g) using growth data, mineralization of the whole body, vertebrae and scales, as well as blood chemistry as response parameters. A total of 192 tambaqui juveniles of approximately 17 ± 0.85 g were stocked into a water recirculation system. Fish were assigned to 24 70L-tanks using randomized block design (two floors) with six treatments (1.3, 2.4, 4.8, 6.3, 7.8 and 8.8 g kg -1 dP) and four replicates. Fish were fed six semi-purified diets with increasing levels of dP for 90 days. The dietary requirement of P was estimated using regression models (P