Inland saline ground water (ISGW) has attracted great interest for commercial aquaculture of marine species in Haryana and Punjab. The silver pompano (Trachinotus blochii), a candidate for mariculture, was investigated for its potential to survive in inland saline water at ICAR-CIFE, Regional Centre, Rohtak, Haryana during 2015–16. The experimental set up comprised ISGW without potassium amendment, ISGW with potassium amendment and artificial sea water of 5 ppt, 10 ppt and 15 ppt salinity. In ISGW without potassium amendment, 100% mortality was observed at 12 h (5 ppt), 24 h (10 ppt) and 48 h (15 ppt). In the second experiment, three treatments (ISW5, ISW10 and ISW15) of ISGW with potassium amendment equivalent to sea water were prepared. A 100% survival was observed at all salinities in ISGW with potassium amendment, similar to the artificial seawater at the end of 90 days. Significantly higher weight gain, specific growth rate (SGR) and average daily growth (ADG) were observed at ISW10 and ISW15 than at ISW5. The plasma osmolality of silver pompano in ISW10 and ISW15 indicated that silver pompano regulates isosmotic condition to maintain the homeostasis of body. The present results indicate that silver pompano can be reared at 10 ppt to 15 ppt salinity with optimum growth and survival in potassium amended ISGW.

The present study elucidates the extracellular synthesis of capped silver nanoparticles (Ag-NPs) using pig processing waste, mainly the intestine in distilled water incubated with silver nitrate by dispensing with the addition of any capping agent and the advantage of avoiding the agglomeration and loss of nanosized characteristics of AgNPs. The synthesis of Ag-NPs was ascertained by a UV-VIS spectrophotometry of the incubated suspension of yellowish-brown at 410 nm. The Ag-NPs were further characterized using a High-Resolution Transmission Electron Microscope (HRTEM), which confirmed that the Ag-NPs were primarily spherical and had a size range of 5–100 with a maximum frequency fall within 5–30 nm. In addition, the Ag-NPs are characterized by Dynamic Light Scattering (DLS), which confirmed the high stability of the Ag-NPs with a zeta potential of -32 mV. Biomolecules and biological extracts of pig waste act as biogenic reducing and capping agents. Based on the zone of inhibition achieved through the agar well diffusion method, the biosynthesis Ag-NPs showed high bactericidal properties against Aeromonas hydrophila, Edwardsiella tarda, and Micrococcus luteus. The chronic toxicity analysis of the biosynthesized Ag-NPs on Pangasianodon hypophthalmus was carried out using stress biomarkers such as an antioxidant enzyme, AChE, and metabolic enzyme activity. Chronic toxicity of synthesized Ag-NPs was found to increase with increased sub-lethal ammonia concentration and temperature. The findings of this study revealed that biosynthesis of capped and non-agglomerated Ag-NPs can be undertaken by using pig wastes for their potential application in aquaculture based on the properties observed in characterization, bactericidal activity, and physiological responses of the fish.

The present study elucidates the extracellular synthesis of capped silver nanoparticles using processing waste (intestine) of sheep and swine in aqueous media and phosphate buffers incubated with silver nitrate by dispensing with the addition of any capping agent and the advantage of avoiding the agglomeration and loss of nanosized characteristics of AgNPs. The synthesis of Ag-NPs was ascertained by UV-VIS spectrophotometry of the incubated suspension of yellowish-brown at 400-410 nm. The Ag-NPs were further characterized using a High-Resolution Transmission Electron Microscope, which confirmed that the Ag-NPs were primarily spherical and had a size range of 5–100 nm with a maximum frequency fall between 5-20 nm, 21-30 nm, 31-50 nm and a few falls within 51-100 nm. In addition, Ag-NPs synthesized using sheep and pig wastes are characterized by Dynamic Light Scattering, which confirmed the high stability of Ag-NPs with a zeta potential of -27 and -32 mV respectively. Biomolecules and biological extracts of sheep and swine waste act as biogenic reducing and capping agents. Based on the zone of inhibition achieved through the agar well diffusion method, Ag-NPs biosynthesized using sheep waste showed high bactericidal properties against Aeromonas hydrophila, Edwardsiella tarda, and Micrococcus luteus as compared to swine waste-derived AgNPs. The chronic toxicity analysis of biosynthesized Ag-NPs on Pangasianodon hypophthalmus was carried out using stress biomarkers such as an antioxidant enzyme, AChE, and metabolic enzyme activity. Chronic toxicity of synthesized Ag-NPs was found to increase with increased sub-lethal ammonia concentration and temperature. The findings of this study revealed that biosynthesis of capped and non-agglomerated Ag-NPs can be undertaken by using sheep and swine wastes for their potential application in aquaculture based on the properties observed in characterization, bactericidal activity, and physiological responses of the fish.

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This study evaluated the effect of different potassium supplementation dosages on the physiological responses of Pangasianodon hypophthalmus reared in an aquaponic system with Spinacia oleracea L. for 60 days. The system comprised of a rectangular fish tank of 168 l capacity (water volume = 100 l) with nutrient film technique (NFT)–based hydroponic component with fish to plant ratio of 2.8 kg m−3: 28 plants m−2 in all the treatments. The osmoregulatory and stress parameters of P. hypophthalmus at four different potassium dosages of T1 (90 mg l−1), T2 (120 mg l−1), T3 (150 mg l−1) and T4 (180 mg l−1) were compared with C (control, 0 mg l−1) to examine the potassium level to be applied to aquaponics. The water quality parameters and fish production were found to have no adverse impact due to potassium supplementation. The spinach yield during two harvests, i.e., before and after potassium supplementation, revealed that the yield was significantly higher (P < 0.05) after supplementation with the highest yield in T3 and T4. The osmoregulatory parameters such as plasma osmolality, Na+, K+ ATPase activity in gill and plasma ionic profile (Cl−, Ca2+ and Na+) showed an insignificant variation (P > 0.05) between control and treatments except for higher plasma potassium concentration (1.98 ± 0.19 mmol l−1) in T4. The stress and antioxidant enzyme analysis exhibited significantly higher plasma glucose and superoxide dismutase (SOD) activity in gill and liver in T4, whereas cortisol and catalase showed an insignificant difference (P > 0.05). The experimental findings demonstrated that the potassium dosage up to 150 mg l−1 could be suggested as optimum for P. hypophthalmus and spinach aquaponics without impairing the health and oxidative status of P. hypophthalmus.