In recent years, the application of micronutrient nanoparticles as dietary supplements has increased in aquaculture research. Nanoparticles have increased surface area, which may facilitate their bioavailability; thereby, improving micronutrient uptake and metabolism. The aim of this study was to evaluate the effects of dietary iron and copper nanoparticles on growth performance and health of channel catfish. A feeding trial was carried out for 9 weeks to evaluate the control (basal iron and copper) and the nanoparticle treatments: iron nanoparticles (FeNP), copper nanoparticles (CuNP), and iron nanoparticles + copper nanoparticles (Fe+CuNP). Iron and copper were included in the control and treatment diets at 500 mg Fe/kg of feed and 10 mg Cu/kg of feed. The growth performance, hematocrit, and the experimental bacterial challenge against Edwardsiella ictaluri have been evaluated. Digesta samples also were collected to evaluate the intestinal microbiota. The DNA samples were extracted, and they will be subjected to 16S rRNA sequencing using Illumina MiSeq. The hematological and immunological parameters and iron quantification in the liver are being analyzed. No significant statistical differences were observed for growth parameters and the bacterial challenge. Interestingly, for hematological parameters, the hematocrit of fish fed with the treatment CuNP was significantly lower compared to the control.
In conclusion, iron nanoparticle supplementation is an innovative strategy to enhance catfish iron uptake. However, the bulk iron and iron nanoparticles did not show statistical differences in this trial. The present study evaluated only a high concentration of iron supplementation. It is hypothesized that, studies evaluating lower concentrations of bulk iron and iron in nanoparticles may possibly show significant differences due to the higher bioavailability of nanoparticles. Furthermore, the statistical difference in hematological parameters between control and CuNP treatments shows the importance of iron supplementation to fish health.