66 SEP TEMBER 2022 • WORLD AQUACULTURE • WWW.WA S .ORG Reproduction. There are a lot of issues in artificial reproduction of commercial species due to incomplete vitellogenesis in females, leading to the failure of the final oocyte maturation and ovulation. To overcome this problem, it is necessary to deliver hormones or drugs in a controlled manner. Chitosan nanoparticles have been used successfully for this as it has the property of slow release of the drugs. Rather et al. (2013) used salmon hormone chitosan-gold nanoparticle complex, thus avoiding the use of multiple injections to enhance reproductive efficacy. Diagnosis of FishPathogens. Nanoparticle-based detection methods are called nano-diagnostics. Nanomaterials act as biosensors, sensing certain recognition elements such as antibodies, aptamers, carbohydrates and produce signals that are optical, electrochemical, magnetic or fluorescent. The most widely used nanoparticles in diagnostics are gold nanoparticles but silver nanoparticles, silicon nanoparticles, quantum dots and nanotubes are also used. Aeromonas salmonicida antibody conjugated AUNP (gold nanoparticle) is utilized for the immunodiagnostics of furunculosis. Conjugation of AU-NPs with a DNA reporter probe used as an electrochemical DNA biosensor for detection of Aphanomyces invadans (Kuan et al. 2013). Water Purification. Compared to conventional water purification technologies, NP has the ability to integrate various properties and is multifunctional. An example is nanocomposite membranes that enable particle retention and elimination of contaminants. Adsorption and photocatalysis are efficient and affordable approaches to purify water. Water quality can be improved using nano-adsorbents, nano-enhanced membranes and nanometal oxides. Nano gold, silver, iron, lanthanum, titanium dioxide and carbon nanotubes (CNT) can be used for the removal of pesticides, ammonia, heavy metals and phosphates. Quantum dots (QDs) are used for the detection of heavy metals in aquaculture media. Photocatalytic activities of TiO2 inactivate pathogenic organisms such as bacteria, viruses and algae. Nanocrystalline cellulose (NCC) removes nitrate from aqueous solution. One innovative technology in water purification is ‘Nano Check’ developed by Altair Nanotechnologies, Inc. that uses 40-nm particles based on lanthanum compounds supporting the absorption of water phosphates, thus limiting algal growth. Lanthanum oxide NPs were used as phosphate scavengers that leads microorganisms to starvation, resulting in a reduction of Escherichia coli, Staphylococcus carnosus, Penicillium roqueforti and Chlorella vulgaris (Gerber et al. 2012). Thai researchers used TiO2 NP to coat ceramic or stone for water treatment in fish bowls to eliminate moss and bacteria in fish tanks. Antimicrobial Activity. Metal nanoparticles have shown high antimicrobial activity against different microbial pathogens. Silver nanoparticles (Ag NP) are the most investigated nano-antibacterial agent. Ag NP synthesized using tea leaf extract had bactericidal activity against V. harveyi in juvenile Fenneropenaeus indicus and TABLE 1. Nanoparticles in fish nutrition. Nanopart i c le (NPS) Spec ies Funct ions Reference Nanoselenium (1 mg/kg) Common carp Enhanced growth Ashouri et al. 2015 and antioxidant activity Selenium (Se), zinc (Zn) Gilthead sea bream Improved stress resistance Izquierdo et al. 2017 and manganese (Mn) NPS Iron NPS and Lactobacillus casei Rainbow trout Improved growth Mohammadi et al. 2015 Iron NPS added with Macrobrachium rosenbergii Promoted growth and Asaikkutti et al. 2016 MnO NPS antioxidant defence system Copper (Cu) NP Macrobrachium rosenbergii PL Elevated growth, enhanced Muralisankar et al. 2016 supplementation digestive enzyme activities, @ 20 mg /kg antioxidant, metabolic enzyme and non-specific immuneresponse Azolla microphyllabased Common carp Hepatoprotective and Kunjiappan et al. 2015 gold NPS (GNPS) antioxidant effect; acts against acetaminophen (APAP)-induced toxicity Aloe Vera NPS Siberian sturgeon Improved growth and survival Sharif Rohani et al. 2017 Ginger (GN) and GN NPS Cyprinus carpio fingerlings Enhanced immunity and Korni and Khalil 2017 prevention of Motile Aeromonas Septicaemia (MAS)
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