*5.1. Aquatic Animals*

The major challenge facing fish farming is the availability of relatively cheap but high-quality feed. Regular fish diet blended with nanosized mineral nutrients has beneficial impact on growth and overall health of fish, because they can pass across the gu<sup>t</sup> tissue into cells more readily than bulk nutrients, and thus their assimilation processes in the fish are accelerated, resulting in improved growth [255].

Thyme essential oil at doses 400 and 800 mg/kg used as a DIS was found to reduce oxidative stress of gibel carp (*Carassius auratus gibelio*; average weight of 8.73 ± 2.1 g), and exposure to a sub-acute toxicity level of AgNPs for a period of 96 h after six weeks of a feeding trial confirmed the resistance of the carp to non-fatal effects of AgNPs [256]. A fish diet containing 1% *Aloe vera* NPs improved the growth factors (weight gain, initial body weight, condition factor, feed conversion ratio, specific growth rate) of Siberian sturgeon [257]. CS NPs showing spherical shape, particle size 185 nm, and positive zeta potential used to carry vitamin C through the GI tract of rainbow trout (*Oncorhynchus mykiss*) exhibited in vivo controlled release until 48 h and increased lysozyme and complement contents in the fish serum [258].

Shrimps (*Litopenaeus vannamei*) reared in clear water and in a biofloc system and receiving feed supplemented with nanocapsules containing lipoic acid showed increased final weight, higher GSH levels in the hepatopancreas and decreased percentage of hyaline hemocytes, while increased levels of granular hemocytes. Increased glutathione *S*-transferase activity in the gills and hepatopancreas was estimated only in shrimps reared in the biofloc system and fed with encapsulated antioxidant, while decreased levels of thiobarbituric acid reactive substances were estimated in the gills and muscles of the shrimps maintained in clear water [259].

A 60-day feeding of red sea bream (*Pagrus major*) with CuNPs (2 mg/kg) or/and vitamin C (800–1200 mg/kg) improved its growth and health, and higher final weight, weight gain, specific growth rate, protein gain, protein retention, feed intake, protease and bactericidal activities, and higher tolerance against stress than in controls was estimated as well. The feed and protein efficiency ratios and the body lipid content were considerably higher at treatment with 0/1200, 2/800, 2/1000 and 2/1200 mg CuNPs/vitamin C per kg, while the application of 2/800, 2/1000 and 2/1200 mg CuNPs/vitamin C per kg resulted in considerably enhanced body protein and higher tolerance against stress compared to the control was estimated as well [260]. Wang et al. [261] reported that for the dietary Cu requirements of Russian sturgeon (9.82 ± 0.08 g) fed with diets containing different forms of Cu for 8 weeks, Cu-methionine (Met) and CuO NPs were 1.5–2-fold more bioavailable than CuSO4, optimal doses being approx. 5 mg/kg for Cu-Met or CuO NPs and 8 mg/kg for CuSO4.

In *Pangasius hypophthalmus* fed with a diet incorporating 10 and 20 mg/kg ZnNPs and exposed to abiotic stress (sublethal dose of Pb 4ppm and temperature 34 ◦C), a considerably enhanced growth performance and improved immunological parameters (total protein, Alb, Glb, and Alb/Glb ratio) were observed, and reduced oxidative stress reflected in lower levels of blood glucose, cortisol, and HSP 70 suggested that the supplementation of dietary ZnNPs could alleviate abiotic stress in

*P. hypophthalmus* [262]. In Mozambique tilapia (*Oreochromis mossambicus*) receiving a diet supplemented with 0.004% of *Portunus pelagicus* β-1,3-glucan binding protein based ZnO NPs, considerable increases in growth performance and in cellular and humoral immune responses were estimated. Moreover, when after 30 days of a feeding trial, the fish was challenged with aquatic fish pathogen *Aeromonas hydrophila* (1 × 10<sup>7</sup> cells/mL) through intraperitoneal injection, a reduced mortality rate was observed in fish fed with the diet containing such ZnO NPs, suggesting a potential beneficial impact of the NPs on the immune system and survival of *O. mossambicus* [263]. Beneficial effects of Zn-proteinate, ZnSO4, and ZnO NPs applied at dose 50 mg/g of Zn sources in an early diet of rainbow trout larvae with average weight of 82.3 ± 11.6 mg for 70 days enhanced the growth performance of the larvae [264].

Common carp (*Cyprinus carpio*) juveniles (9.7 ± 0.1 g), the diet of which was supplemented with SeNPs (0.7 mg Se/kg), showed the highest weight gain of 97.2 ± 10.8% and feed efficiency ratio 42.4 ± 0.8%, the highest serum hemolytic activity, total immunoglobulin, and total protein and Alb contents as well as the lowest serum total cholesterol and LDL levels after 8 weeks of feeding compared to the carp fed with Na2SeO3, Se-Met, and the control. Carps fed with SeNPs or Se-Met showed also pronouncedly higher activities of serum glutathione peroxidase (GPx) and SOD and an increase in white blood cell counts, neutrophil percentage, and serum lysozyme activity compared to the control group and the Na2SeO3 group [265]. Dietary treatments of crucian carp, *Carassius auratus gibelio*, with SeNPs and Se-Met showed higher Se levels in muscle (16.42 ± 1.07 μg/g and 13.52 ± 1.31 μg/g, respectively) compared to carps fed with basal feed (6.10 ± 0.78 μg/g). Although the survival rate and the feed conversion ratio were not affected by the dietary treatments, GPx activities in Se-treated carp plasma and liver differed significantly from those of the control [266]. Dietary SeNPs supplementation at the dose of 0.68 mg/kg to juvenile mahseer (*Tor putitora*) considerably increased red blood cell count, hemoglobin level, hematocrit values, and lysozyme activity as well as serum GH levels, tissue total protein content, and GPx activity in liver and muscle tissues of *T. putitora* [267]. Chinese mitten crabs (*Eriocheir sinensis*) fed with a diet containing 0.2 mg/kg SeNPs in a 60 d feeding trial had a considerably higher weight gain rate and a reduced feed coefficient. When juvenile Chinese mitten crabs were kept under the condition of hypoxia, the up-regulative effects of SeNPs on antioxidant capacity, hemocyte counts, and hemocyanin expression were further amplified. Hypoxia exposure increasing mortality in crabs infected with *A. hydrophila* bacteria was also alleviated when crabs received a diet containing 0.2 mg/kg SeNPs, suggesting the importance of dietary SeNPs in regulating the immunity and disease resistance in crabs kept under hypoxia stress [268]. Naderi et al. [269] who investigated the impact of dietary SeNPs (1 mg/kg), vitamin E (500 mg/kg), and their combination on the humoral immune status and serum parameters of rainbow trout under high-density condition (80 kg/m3) reported that the positive effects observed in the performance following the combine treatment may be due to vitamin E alone, because supplementation with SeNPs did not markedly affect the performance in rainbow trout under high-density conditions. In addition, the immuno-protective role of biologically synthesized dietary SeNPs applied at the dose of 1 mg/kg against multiple stressors (Pb level of 4 ppm, high temperature of 34 ◦C) in *Pangasinodon hypophthalmus* was reported by Kumar et al. [270].
