A review article on nanotechnology in aquaculture sustainability as a novel tool in fish disease control

Dietary nano-Selenium supplementation improves growth performance, nutrient digestibility and hematology in Cirrhinus mrigala fingerlings

The following investigation was carried out to determine the effects of Selenium nanoparticles (Se NPs) on the growth rates, nutrient digestibility, and hematology of Cirrhinus mrigala fingerlings fed sunflower meal as basal diet. The experiment included seven test diets with varying Se levels (0, 0.5, 1, 1.5, 2, 2.5, and 3 mg/kg) based on Se NPs supplementation. Chromic oxide, an inert maker, was also added. Fingerlings were fed at a rate of 5% of their body weight. The test meal of 1 mg/kg Se NPs resulted in the highest weight gain (12.31 g) and the lowest feed conversion ratio (1.58). Best hematological indices (RBCs 2.84 106 mm-3, WBCs 7.79 103 mm-3, PLT 66, Hb 8.5 g/100 ml, PCV 25% and MCV 190 fl) and maximum nutrient absorption (crude protein 72%, ether extract 73% and gross energy 67%) were also observed in the case of 1 mg/kg supplementation of Se NPs. Hematology studies indicated that when fish were fed 0.5 mg/kg Se NPs, their levels began to rise. Maximum results were achieved with feed containing 1 mg/kg of Se NPs, but when the concentration increased above 1 mg/kg, the values began to decline. Instead, nutrient digestibility began to increase when the concentration of Se NPs increased to 1 mg/kg and abruptly started to decline with a further increase in Se NPs. The results demonstrated that a sunflower meal-based diet supplemented with Se NPs (1 mg/kg) increased the growth performance, nutritional digestibility, and hematology of C. mrigala fingerlings.

Molecular, behavioral, and growth responses of juvenile yellow catfish (Tachysurus fulvidraco) exposed to carbamazepine

Carbamazepine (CBZ) is an anticonvulsant medication used to treat epilepsy and bipolar disorder. Due to its persistence and low removal rate in wastewater treatment plants, it is frequently detected in the environment, raising concerns regarding its potential adverse effects on aquatic organisms and ecosystems. In this study, we aimed to assess the impact of CBZ on the behavior and growth of juvenile yellow catfish Tachysurus fulvidraco, a native and economically important species in China. Fish were exposed to CBZ at three concentrations of 1, 10, or 100 µg/L for 14 days. The fish exposed to 10 and 100 μg/L of CBZ exhibited decreased feeding, and a significant increase in cannibalistic tendencies was observed in fish exposed to 100 μg/L CBZ. Acetylcholinesterase activity was increased in the brain of fish exposed to 100 μg/L CBZ. CBZ also inhibited the growth of yellow catfish. To better elucidate mechanisms of toxicity, transcriptomics was conducted in both the brain and liver. In the brain, gene networks associated with neurotransmitter dysfunction were altered by CBZ, as well as networks associated with mitochondrial dysfunction and metabolism. In the liver, gene networks associated with the immune system were altered by CBZ. The current study improves comprehension of the sub-lethal effects of CBZ and reveals novel insight into molecular and biochemical pathways disrupted by CBZ, identifying putative key events associated with reduced growth and altered behavior. This study emphasizes the necessity for improved comprehension of the effects of pharmaceutical contaminants on fish at environmentally relevant levels.

Bacterial diseases of Asian sea bass (Lates calcarifer): A review for health management strategies and future aquaculture sustainability

The advent of aquaculture has been one of the most significant shifts in world food supply during the last century. Aquaculture has rapidly expanded and become a global food industry, spurred by population expansion, increased seafood consumption, and decreased captured fisheries. Nonetheless, the exponential growth of aquaculture has emerged as a significant contributor to anthropogenic changes. Unexpectedly, the result has focused in the emergence and spread of new diseases. The Asian sea bass (Lates calcarifer) is an economically important species in aquaculture, contributing significantly to the global seafood market. However, bacterial diseases have emerged as a major concern, affecting both wild and cultured populations of this species. The most prevalent bacterial pathogens are streptococcus, vibriosis, nocardiosis, tenacibaculosis, and pot-belly disease. Therefore, this review aims to comprehensively analyze both emerging and non-emerging bacterial diseases affecting L. calcarifer and explore potential management approaches for their control. Through an extensive literature survey and critical evaluation of research findings, this review highlights the current understanding of bacterial diseases in L. calcarifer and proposes strategies for better disease management. In addition, this review looks at the rise and characteristics of aquaculture, the major bacterial pathogens of L. calcarifer and their effects, and the specific attributes of disease emergence in an aquatic rather than terrestrial context. It also considers the potential for future disease emergence in L. calcarifer due to aquaculture expansion and climate changes.

A novel metabolite of Streptomyces coeruleorubidus exhibits antibacterial activity against Streptococcus agalactiae through modulation of physiological performance, inflammatory cytokines, apoptosis, and oxidative stress-correlated gene expressions in Nile tilapia (Oreochromis niloticus)

Using the unique structures found in natural materials to produce new antibacterial drugs is crucial. Actinobacteria is well-known for its ability to produce naturally occurring chemicals with a variety of structural features that can be used as weapons against infectious bacteria. In the present study, the Streptomyces coeruleorubidus metabolites were characterized and their efficacy in suppressing Streptococcus agalactiae growth was carried out both in vitro and in vivo. The metabolites of S. coeruleorubidus were purified and identified as octasiloxane-hexadecamethyl (OHM). In vivo antibacterial activity of OHM revealed an inhibitory minimum concentration value of 0.5 μg/ml against S. agalactiae and induced ultrastructural cell changes revealed by scanning electron microscope. The safe concentration of OHM was determined as 0.8 mg/L for Nile tilapia. Four in vivo treatments were treated with 0 and 0.8 mg/L OHM and with or without challenge by S. agalactiae (1 × 107 CFU/mL) named control, OHM, S. agalactiae, and S. agalactiae + OHM groups. The OHM treatment improved the survival of Nile tilapia by 33.33% than S. agalactiae challenge group. Waterborne OHM treatment significantly mitigated the deleterious effects of S. agalactiae on hematological, hepato-renal functions, stress indicators, and antioxidant balance. OHM significantly alleviated nitric oxide levels, complement 3, IgM, and lysozyme activity, downregulation of liver antioxidant genes expression in S. agalactiae group. Furthermore, the addition of OHM to challenged fish with S. agalactiae-significantly reversed dramatic negative regulation of inflammatory, apoptosis, and immune related gene expression (caspase-3, bax, pcna, tnf-α, ifn-γ, il-8 il-1β, il-10, tgf-β, and bcl-2 in the Nile tilapia spleen. Additionally, the damaged hepatic and splenic structure induced by bacterial infection was restored with OHM treatment. Finally, S. coeruleorubidus metabolites (mainly OHM) revealed in vitro and in vivo antibacterial activity and showed alleviated effects on the physiological status of S. agalactiae infected tilapia.

Biogenic silver nanoparticles: Synthesis, applications and challenges in food sector with special emphasis on aquaculture

Aquaculture, a rapidly expanding global food sector faces challenges like pathogenic infections, water quality management and sustainability. Silver nanoparticles (AgNPs) have emerged as promising tools in aquaculture due to their antimicrobial, antiviral and antifungal properties. AgNPs offer alternatives to traditional antimicrobial agents. Their small size and unique physicochemical properties enhance antimicrobial activity, effectively inhibiting pathogen growth and reducing disease incidence in aquatic organisms. Additionally, AgNPs can improve water quality by catalyzing the removal of pollutants, heavy metals and nutrients, reducing environmental impacts. Despite their potential benefits, several challenges and knowledge gaps exist in the utilization of AgNPs in aquaculture. Addressing challenges related to regulation, sustainability and environmental impact will be crucial for realizing their full potential in the industry. Therefore, the present review aims to provide insight into the role of AgNPs, its challenges in aquaculture and also highlights key areas for future research.

Potentials of Aloe barbadensis inclusion in fish feeds on resilience to Aeromonas hydrophila infection in freshwater fish Labeo rohita

Aquatic bacterial pathogens can cause severe economic loss in aquaculture industry. An opportunistic pathogen, Aeromonas hydrophila is responsible for Motile Aeromonas Septicemia, leading to high mortality rates in fish. The present study was focused on the efficacy of Aloe barbadensis replacing fishmeal diets on hematological, serum biochemical, antioxidant, histopathological parameters, and disease resistance against A. hydrophila infection in Labeo rohita. Isonitrogenous fishmeal replaced diets (FMR) were prepared with varying levels of A. barbadensis at D1 (0%) (control), D2 (25%), D3 (50%), D4 (75%) and D5 (100%) then fed to L. rohita. After 60 days of post-feeding, the experimental fish were challenged with A. hydrophila. Blood and organs were collected and examined at 1- and 15-days post infection (dpi). The results demonstrated that on 1 dpi, white blood cells (WBC), total protein, cholesterol and low-density lipoprotein (LDL) levels were significantly increased in D3 diet fed groups. The D2 and D3 diet fed group showed decreasing trends of serum glutamic pyruvic transaminase (SGPT) and antioxidant enzymes activity on 15 dpi. The histopathological architecture results clearly illustrated that the D3 diet fed group had given a higher protective effect by reducing the pathological changes associated with A. hydrophila infection in liver, intestine and muscle. Higher percentage of survival rate was also observed in D3 diet fed group. Therefore, the present study suggested that the dietary administration of A. barbadensis up to 50% fishmeal replacement (D3 diet) can elicit earlier antioxidant activity, innate immune response and improve survival rate in L. rohita against A. hydrophila infection.

Current risks of microbial infections in fish and their prevention methods: A review

A fast-expanding sector of agriculture worldwide is aquaculture. The production of fish internationally accounts for around 44 % of the total. Even though the aquaculture environment presents several difficulties, the current development in aquaculture production comes with an increase in infectious diseases, which significantly impacts the production, profitability, and sustainability of the worldwide aquaculture business. Many infectious agents, such as bacteria, viruses, fungi and parasites are causative agents for fish infections. Most infectious diseases found in all types of fish like marine water, freshwater and ornamental fishes are caused by bacteria, with many of them serving as secondary opportunistic invaders that attack sick animals by affecting their natural host immunity. To overcome this, addressing health issues based on methods that have been scientifically verified and advised will help lessen the effects of fish disease. This review aims to highlight some of the common microbial-infecting agents of fish in all types of aquatic systems and their effective methods for preventing infections in aquaculture.

Clinical Assessment of Thermotherapy Applications during Hepatectomy and Laparotomy in Sturgeon (Acipenser ruthenus): Impact on Bioparameter Variations Based on Liver Condition

Surgical techniques are gaining attention for treating physical diseases in aquaculture and aquarium fish. Sturgeon is a suitable species for surgical experiments due to its industrial significance. Maintaining homeostasis is crucial during surgical procedures, and the liver plays a major role in immune regulation. High temperature is suggested to improve physiological activity and wound healing. This study investigated differences in hepatectomy sturgeons' tolerance and histopathological responses of internal organs. Moreover, this study investigated the effects of high temperatures on wound healing and hematopoietic recovery in fish undergoing surgical procedures. The liver condition was found to play a pivotal role in the analysis, and cortisol levels were affected by anesthesia. The results showed that high temperature facilitated hematopoietic recovery and wound healing, but excessive induction of physiological activity caused damage. Managing high temperatures and liver conditions induced a remarkable improvement in wound healing. However, anesthesia itself can be a significant stressor for fish, and wound healing requires a greater amount of energy. Further research is needed to understand the stress factors caused by surgical procedures and anesthesia and to promote animal welfare in fishery products.

Meeting Contemporary Challenges: Development of Nanomaterials for Veterinary Medicine

In recent decades, nanotechnology has been rapidly advancing in various fields of human activity, including veterinary medicine. The review presents up-to-date information on recent advancements in nanotechnology in the field and an overview of the types of nanoparticles used in veterinary medicine and animal husbandry, their characteristics, and their areas of application. Currently, a wide range of nanomaterials has been implemented into veterinary practice, including pharmaceuticals, diagnostic devices, feed additives, and vaccines. The application of nanoformulations gave rise to innovative strategies in the treatment of animal diseases. For example, antibiotics delivered on nanoplatforms demonstrated higher efficacy and lower toxicity and dosage requirements when compared to conventional pharmaceuticals, providing a possibility to solve antibiotic resistance issues. Nanoparticle-based drugs showed promising results in the treatment of animal parasitoses and neoplastic diseases. However, the latter area is currently more developed in human medicine. Owing to the size compatibility, nanomaterials have been applied as gene delivery vectors in veterinary gene therapy. Veterinary medicine is at the forefront of the development of innovative nanovaccines inducing both humoral and cellular immune responses. The paper provides a brief overview of current topics in nanomaterial safety, potential risks associated with the use of nanomaterials, and relevant regulatory aspects.

Nano-selenium impacts on growth performance, digestive enzymes, antioxidant, immune resistance and histopathological scores of Nile tilapia, Oreochromis niloticus against Aspergillus flavus infection

The present study examined the impacts of varying amounts of selenium nanoparticles (Se-NPs) as a natural antioxidant and metabolic regulator on growth performance, antioxidant capacity, digestive enzymes and immune resistance of Oreochromis niloticus challenged to Aspergillus flavus infection. For 60 days, fish were fed the experimental diet of 30% crude protein up to apparent satiation three times a day. Se-NPs were added to the control diet at different levels of 0.0 (control), 0.5 (T1), 1.0 (T2) and 1.5 (T3) mg/kg diet to fed monosex Nile tilapia fingerlings with average initial weight (4.5 ± 0.5 g). Fish were randomly distributed in 12 tanks 100 L at a density of 20 fish per tank after 2-week acclimation to represent four treatments in triplicates. The results indicated that the growth indices, feed efficiency and survival rate were significantly enhanced (P < 0.05) by incorporating Se-NPs up to 1 mg/kg diet. Furthermore, the haemato-biochemical parameters, digestive enzymes activity and antioxidant capacity of the fish were significantly improved (P < 0.05) at T2. When the fish were challenged with Aspergillus flavus, a decreasing mortality rate was observed, which clearly shows that selenium nanoparticles boosted the fish’s immune response at T2. The intestinal morphology as villus length, villus width, muscular fibres layer thickness and absorption intestinal zone after challenged with A. flavus infection were considerably enhanced (P < 0.05) by incorporating all Se-NP levels. Histopathological score significantly improved (P < 0.05) for the hepatopancreatic, intestinal, gills and muscle tissues at T2. The present study concludes that selenium nanoparticles up to 1.0 mg/kg diet can be efficiently used in tilapia feed to help boost fish production, immune system response and histopathological parameters.

Chitosan nanoparticles and green synthesized silver nanoparticles as novel alternatives to antibiotics for preventing A.hydrophila subsp. hydrophila infection in Nile tilapia, Oreochromis niloticus

Recently, nanoparticles have attracted attention as a preventive tool for certain infectious diseases affecting fish in aquaculture. Furthermore, freshwater fishes are frequently vulnerable to summer mass morality caused by Aeromonas bacteria. In this regard, we focused on the evaluation of the in vitro and in vivo antimicrobial activity of chitosan (CNPs) and silver (AgNPs) nanoparticles against Aeromonas hydrophila subsp. hydrophila. CNPs and AgNPs were prepared at a mean particle size of 9.03 and 12.8 nm and a charge equalled+36.4 and -19.3 mV for CNPs and AgNPs, respectively. A. hydrophila subsp. hydrophila, Aeromonas caviae, and Aeromonas punctata were retrieved and identified by traditional and molecular techniques. The sensitivity of the obtained bacteria to eight different antibiotic discs was also tested. The antibiotic sensitivity studies revealed the presence of multidrug-resistant (MDR) Aeromonas species (spp.). The bacterium that showed the highest multidrug resistance against the tested antibiotic discs was Aeromonas hydrophila subsp. hydrophila. Therefore, CNPs and AgNPs were in vitro tested against the isolated bacterium and exhibited inhibition zones of 15 and 25 mm, respectively. TEM images also showed that CNPs and AgNPs had an antagonistic action against the same bacterium causing loss of architecture and bacterial death.

Exopolysaccharides-Mediated ZnO Nanoparticles for the Treatment of Aquatic Diseases in Freshwater Fish Oreochromis mossambicus

Bacterial fish disease outbreaks are a key concern for aquaculture. Complementary feed additives such as immunostimulants can serve as an ideal solution for disease prevention. Herein, we scrutinized the efficacy of exopolysaccharides (EPSs) from probiotic Bacillus licheniformis and EPS-mediated zinc oxide nanoparticles (EPS-ZnO NPs) for a diet to evaluate growth parameters, antioxidant enzyme activities, and immune stimulation together with disease resistance against Aeromonas hydrophila and Vibrio parahaemolyticus in Mozambique tilapia Oreochromis mossambicus. Fish were separated into seven groups, with six experimental groups fed with EPS and EPS-ZnO NPs at 2, 5, and 10 mg/g and a control fed a basal diet. The fish ingesting feed supplemented with EPS and EPS-ZnO NPs at 10 mg/g showed improved growth performance. Cellular and humoral-immunological parameters were tested in serum and mucus after 15 and 30 days of feeding. These parameters were substantially enriched with a 10 mg/g diet (p < 0.05) of EPS and EPS-ZnO NPs in comparison with the control. Furthermore, the EPS and EPS-ZnO NP supplemental diet actively enhanced the antioxidant response (glutathione peroxidase, superoxide dismutase, and catalase). In addition, the supplemental diet of EPS and EPS-ZnO NPs lowered the death rate and improved the disease resistance of O. mossambicus following assessment with A. hydrophila and V. parahaemolyticus at 50 µL. Hence, the overall results suggest that the supplemental diet of EPS and EPS-ZnO NPs might be used to ensure aquaculture feed additives.

Silver nano/microparticle toxicity in the shrimp Litopenaeus vannamei (Boone, 1931)

The effects of silver nano/microparticles (AgP) on juvenile Litopenaeus vannamei shrimp were evaluated through several responses, aiming to use it as a prophylactic and therapeutic method. Shrimps (3.19 ± 0.13 g) were exposed to clear water for 3 h with increasing concentrations of nanosilver (0; 25; 100; and 400 μg/l). After 3 h of exposure, they were transferred to water without nanosilver for 30 days (recovery). The weight gain and weekly growth were not affected by AgNP. Total antioxidant capacity (ACAP) increased in the hepatopancreas (exposure period) and gills (recovery) in shrimp exposed to AgNP. In muscle, ACAP was induced in shrimp exposed to 100 μg/l AgNP (exposure). In the gills, there was an increase in TBARS in shrimp exposed to 100 μg/l AgNP (recovery). In the concentration of protein-associated sulfhydryl groups (P-SH), a decrease was observed in the hepatopancreas (recovery) in the 100 μg/l AgNP treatment. In chromaticity parameters, an increase in reddish tones was observed in shrimp exposed to 100 μg/l AgNP (recovery). An increase in granular hemocytes was verified in shrimp exposed to 25 and 400 μg/l AgNP during exposure. Tissues analyzed histologically showed normal patterns without apoptosis or necrosis processes, and after 30 d of recovery, only in one muscle sample of shrimp exposed to μg/l of AgNP was silver detected. It is concluded that a prophylactic action of short duration (3 h) mostly did not affected the welfare of shrimp L. vannamei and can be considered its use as a therapeutic strategy.

Effects of polysaccharide-based silver and selenium nanoparticles on growth performance, biochemical parameters, and immune response of Cyprinus carpio

•

Comparative effects of polysaccharide-based AMLP-AgNPs and AMLP-SeNPs on Cyprinus carpio were investigated.

•

Fish that received dietary AMLP-SeNPs showed enhanced growth performance,improved  immune systems , antioxidant defense systems and normalize blood biochemical parameters.

•

Dietary AMLP-SeNPs and AMLP-AgNPs showed a higher percentage of survivability after A. hydrophila infection.

•

Total A. hydrophila count in blood and muscles was found to be lower in fish fed with dietary AMLP-SeNPs followed by AMLP-AgNPs.

•

These findings suggested that applying nanotechnology to aquaculture could offer up new opportunities, such as reducing feed nutrient losses, increasing faster growth.

Avicennia marina mangrove leaves polysaccharide (AMLP) was used for the synthesis of polysaccharide-based selenium (AMLP-SeNPs) and silver nanoparticles (AMLP-AgNPs). The synthesized nanoparticles were further characterized by UV-Vis, DLS, FT-IR, X-ray diffraction, and HR-TEM analysis. A 60-day (8 weeks) feeding trial experiment was conducted to investigate the effects of AMLP, AMLP-SeNPs, and AMLP-AgNPs dietary supplementation on growth performance parameters, blood parameters, immunological and enzymatic profiles in Cyprinus carpio. The characterization results of AMLP-SeNPs and AMLP-AgNPs confirmed the formation of well-stabilized spherical nanoparticles with a mean particle size of 37.25 and 72.40 nm, respectively having a crystalline structure. The feeding experiment results demonstrated that 2 mg/kg of AMLP-SeNPs followed by 0.2 mg/kg of AMLP-AgNPs showed significantly (p ˂ 0.05) higher final weight, weight gain (WG), specific growth rate (SGR%), protein and lipid efficiency, and lower food conversion ratio as compared to other groups. The catalase, superoxidase dismutase, and glutathione peroxidase activity were significantly (p ˂ 0.05) higher in the group fed 2 mg/kg supplemented AMLP-SeNPs. Total protein and globulin contents were significantly (p ˂ 0.05) higher and albumin concentration was significantly lower in fish that received 2 mg/kg of AMLP- SeNPs as compared to control. A significant increase in serum HDL and decrease in LDL and MDA concentrations were observed in the group supplemented with 2 mg/kg of nano selenium. The body's crude lipid, protein, moisture, and ash were not significantly different from the control. The AMLP-SeNPs showed significantly (p ˂ 0.05) lower aspartate aminotransferase (AST), alanine aminotransferase (ALT), and higher alkaline phosphatase (ALP) activities compared to other test groups. The relative percentage survivability (RPS%) was higher in AMLP-SeNPs (84.6%) followed by AMLP-AgNPs (76.7%) after 8^th weeks of supplementary diets as compared to control groups. Overall, the finding of these studies revealed that the inclusion of AMLP-SeNPs improved the growth performance and antioxidant defense system, enhance immune response, and provide resistance against Aeromonas hydrophila in Common carp.

Current status and development prospects of aquatic vaccines

Diseases are a significant impediment to aquaculture's sustainable and healthy growth. The aquaculture industry is suffering significant financial losses as a result of the worsening water quality and increasing frequency of aquatic disease outbreaks caused by the expansion of aquaculture. Drug control, immunoprophylaxis, ecologically integrated control, etc. are the principal control strategies for fish infections. For a long time, the prevention and control of aquatic diseases have mainly relied on the use of various antibiotics and chemical drugs. However, long-term use of chemical inputs not only increases pathogenic bacteria resistance but also damages the fish and aquaculture environments, resulting in drug residues in aquatic products, severely impeding the development of the aquaculture industry. The development and use of aquatic vaccines are the safest and most effective ways to prevent aquatic animal diseases and preserve the health and sustainability of aquaculture. To give references for the development and implementation of aquatic vaccines, this study reviews the development history, types, inoculation techniques, mechanisms of action, development prospects, and challenges encountered with aquatic vaccines.

Chitosan-nanoparticles effects on mucosal immunity: A systematic review

Nanoparticles-based treatments is of utmost importance for aquaculture. In this scenario, chitosan-based nanoparticles have been proposed due to the properties of chitosan, which include mucoadhesiveness. Nevertheless, pivotal parameters of chitosan, such as degree of acetylation and molecular weight, are commonly underestimated in the available literature despite the influence they seem to have on the properties of chitosan-based nanoparticles. In this systematic review, the immunomodulator capacity of chitosan nanoparticles used as mucosal vaccines on teleost fish has been evaluated paying special attention to the chitosan properties. Four databases were used for literature search, yielding 486 documents, from which 14 meet the inclusion criteria. Only 21% of the available studies reported properly chitosan properties, which should be improved in future works to generate reproducible data as well as valuable information. To the best of our knowledge, this work objectively compares for the first time, by quantifying the mg of chitosan/g of fish applied in each study, the chitosan nanoparticle preparation and doses applied to fish, as well as the effects of the treatments applied on fish immune status.

Antibiotic resistance in aquaculture and aquatic organisms: a review of current nanotechnology applications for sustainable management

Aquaculture has emerged as one of the world's fastest-growing food industries in recent years, helping food security and boosting global economic status. The indiscriminate disposal of untreated or improperly managed waste and effluents from different sources including production plants, food processing sectors, and healthcare sectors release various contaminants such as bioactive compounds and unmetabolized antibiotics, and antibiotic-resistant organisms into the environment. These emerging contaminants (ECs), especially antibiotics, have the potential to pollute the environment, particularly the aquatic ecosystem due to their widespread use in aquaculture, leading to various toxicological effects on aquatic organisms as well as long-term persistence in the environment. However, various forms of nanotechnology-based technologies are now being explored to assist other remediation technologies to boost productivity, efficiency, and sustainability. In this review, we critically highlighted several ecofriendly nanotechnological methods including nanodrug and vaccine delivery, nanoformulations, and nanosensor for their antimicrobial effects in aquaculture and aquatic organisms, potential public health risks associated with nanoparticles, and their mitigation measures for sustainable management.

A Novel Efficient Piscine Oral Nano-Vaccine Delivery System: Modified Halloysite Nanotubes (HNTs) Preventing Streptococcosis Disease in Tilapia (Oreochromis sp.)

Generally, the injection method is recommended as the best efficient method for vaccine applications in fish. However, labor-intensive and difficult injection for certain fish sizes is always considered as a limitation to aquatic animals. To demonstrate the effectiveness of a novel oral delivery system for the piscine vaccine with nano-delivery made from nano clay, halloysite nanotubes (HNTs) and their modified forms were loaded with killed vaccines, and we determined the ability of the system in releasing vaccines in a mimic digestive system. The efficaciousness of the oral piscine vaccine nano-delivery system was evaluated for its level of antibody production and for the level of disease prevention in tilapia. Herein, unmodified HNTs (H) and modified HNTs [HNT-Chitosan (HC), HNT-APTES (HA) and HNT-APTES-Chitosan (HAC)] successfully harbored streptococcal bivalent vaccine with inactivated S. agalactiae, designated as HF, HAF, HCF and HACF. The releasing of the loading antigens in the mimic digestive tract demonstrated a diverse pattern of protein releasing depending on the types of HNTs. Remarkably, HCF could properly release loading antigens with relevance to the increasing pH buffer. The oral vaccines revealed the greatest elevation of specific antibodies to S. agalactiae serotype Ia in HCF orally administered fish and to some extent in serotype III. The efficacy of streptococcal disease protection was determined by continually feeding with HF-, HAF-, HCF- and HACF-coated feed pellets for 7 days in the 1st and 3rd week. HCF showed significant RPS (75.00 ± 10.83%) among the other tested groups. Interestingly, the HCF-treated group exhibited noticeable efficacy similar to the bivalent-vaccine-injected group (RPS 81.25 ± 0.00%). This novel nano-delivery system for the fish vaccine was successfully developed and exhibited appropriated immune stimulation and promised disease prevention through oral administration. This delivery system can greatly support animals’ immune stimulation, which conquers the limitation in vaccine applications in aquaculture systems. Moreover, this delivery system can be applied to carrying diverse types of biologics, including DNA, RNA and subunit protein vaccines.

Selenium as an important factor in various disease states - a review

Selenium (Se) is an element that has a pro-health effect on humans and animals. However, both the deficiency of this element and its excess may prove harmful to the body depending on the chemical form of the selenium, the duration of supplementation, and the human health condition. Many data indicate insufficient coverage of the demand for selenium in humans and animals due to its low content in soils and food products. A balance in the physiological process of the body can be achieved via the proper percentage of organically active minerals in the feed of animals as well as human beings. Selenium is a trace mineral of great importance to the body, required for the maintenance of a variety of its processes; primarily, selenium maintains immune endocrine, metabolic, and cellular homeostasis. Recently, this element has been emerging as a most promising treatment option for various disorders. Therefore, research based on Se has been increasing in recent times. The present review is designed to provide up-to-date information related to Se and its different forms as well as its effects on health.

Growth Performance, Antioxidative Capacity, and Intestinal Histomorphology of Grey Mullet (Liza ramada)-Fed Dietary Zinc Nanoparticles

Zinc is one of the essential microelements involved in vital physiological and biological functions in the fish body. The study evaluated the growth performance, antioxidative capacity, and intestinal histomorphology of Grey Mullet (Liza ramada)-fed dietary zinc nanoparticles (ZnO-NPs) at 0, 10, 20, and 40 mg/kg for the first time. The final weight and specific growth rate (SGR) of Grey Mullet-fed dietary ZnO-NPs at 20 and 40 mg/kg were meaningfully enhanced (p < 0.05). Further, the weight gain (WG) was significantly higher in fish treated with ZnO-NPs than the control, and fish fed 20-40 mg/kg had the highest WG (p < 0.05). The feed conversion ratio (FCR) was meaningfully reduced in fish fed 20-40 mg ZnO-NPs/kg (p < 0.05). The histomorphology of the intestines revealed a significant improvement in villus height, villus width, and goblet cells by ZnO-NPs. The lysozyme activity, phagocytic activity, and phagocytic index showed higher levels in Grey Mullet-fed dietary ZnO-NPs at 20 mg/kg than fish fed 0, 10, and 40 mg/kg (p < 0.05). Superoxide dismutase (SOD) and catalase (CAT) were markedly improved in Grey Mullet treated with ZnO-NPs compared with the control, and the group of fish treated with 20 mg/kg had the highest SOD and CAT (p < 0.05). Glutathione peroxidase (GPx) was significantly higher in fish fed 20-40 mg/kg ZnO-NPs than fish fed 0-10 mg/kg and fish fed 40 mg ZnO-NPs/kg showing the highest GPx value (p < 0.05). The concentration of malondialdehyde was markedly lowered in Grey Mullet fed ZnO-NPs at varying levels (p < 0.05). Based on the overall results, the regression analysis suggests that ZnO-NPs can be included at 24.61-35.5 mg/kg for the best performances of Grey Mullet.

Evaluation of Metal‐Organic Framework MIL-89 nanoparticles toxicity on embryonic zebrafish development

Metal-Organic Framework MIL-89 nanoparticles garnered remarkable attention for their widespread use in technological applications. However, the impact of these nanomaterials on human and environmental health is still limited, and concerns regarding the potential risk of exposure during manipulation is constantly rising. Therefore, the extensive use of nanomaterials in the medical field necessitates a comprehensive assessment of their safety and interaction with different tissues of the body system. In this study, we evaluated the systemic toxicity of nanoMIL-89 using Zebrafish embryos as a model system to determine the acute developmental effect. Zebrafish embryos were exposed to a range of nanoMIL-89 concentrations (1 – 300 µM) at 4 h post-fertilization (hpf) for up to 120 hpf. The viability and hatching rate were evaluated at 24–72 hpf, whereas the cardiac function was assessed at 72 and 96 hpf, and the neurodevelopment and hepatic steatosis at 120 hpf. Our study shows that nanoMIL-89 exerted no developmental toxicity on zebrafish embryos at low concentrations (1–10 µM). However, the hatching time and heart development were affected at high concentrations of nanoMIL-89 (> 30 µM). Our findings add novel information into the available data about the in vivo toxicity of nanoMIL-89 and demonstrate its innocuity and safe use in biological, environmental, and medical applications.

•

NanoMIL-89 is not lethal for zebrafish embryos.

•

High concentrations of nanoMIL-89 alter the heart development and delay the hatching time in zebrafish embryos.

•

Low concentrations of nanoMIL-89 showed no significant organ specific toxicity effects on zebrafish embryos.

A review on the recent advances and application of vaccines against fish pathogens in aquaculture

Globally, aquaculture has faced serious economic problems due to bacterial, viral, and various other infectious diseases of different origins. Even though such diseases are being detected and simultaneously treated with several therapeutic and prophylactic methods, the broad-spectrum activity of vaccines plays a vital role as a preventive measure in aquaculture. However, treatments like use of antibiotics and probiotics seem to be less effective when new mutant strains develop and disease causing pathogens become resistant to commonly used antibiotics. Therefore, vaccines developed by using recent advanced molecular techniques can be considered as an effective way of treating disease causing pathogens in aquatic organisms. The present review emphasizes on the current advances in technology and future outlook with reference to different types of vaccines used in the aquaculture industries. Beginning with traditional killed/inactivated and live attenuated vaccines, this work culminates in the review of modern new generation ones including recombinant, synthetic peptides, mucosal and DNA, subunit, nanoparticle-based and plant-based edible vaccines, reverse vaccinology, and monovalent and polyvalent vaccines.