Dietary supplementation of Zeolite on growth performance, immunological role, and disease resistance in Channa striatus against Aphanomyces invadans

Bentonite-supplemented diets improved fish performance ammonia excretion haemato-biochemical analyses immunity antioxidants and histological characteristics of European seabass Dicentrarchus labrax

The purpose of this research was to examine the potential effects of bentonite (BN) supplemented diets on growth, feed utilization, blood biochemistry, and histomorphology of Dicentrarchus labrax. Six treatments in triplicate were tested: B0, B0.5, B1.0, B1.5, B3.0, and B4.5, which represented fish groups fed diets supplemented with 0, 0.5, 1, 1.5, 3, and 4.5% BN, respectively. For 84 days, juveniles' seabass (initial weight = 32.73 g) were fed diets containing 46% protein, three times daily at 3% of body weight. With a 5% daily water exchange, underground seawater (32 ppt) was used. Findings revealed significant improvements in water quality (TAN and NH3), growth (FW, WG and SGR) and feed utilization (FCR, PER and PPV) in fish fed BN-supplemented diets, with the best values in favor of the B1.5 group. Additional enhancements in kidney function indicators (urea and uric acid) and liver enzymes were observed in fish of the BN-treated groups along with a decrease in cholesterol level in the B1.5 group. Further improvements in fish innate immunity (hemoglobin, red blood cells, glucose, total protein, globulin, and immunoglobulin IgM), antioxidant activity (total antioxidative capacity and catalase), and decreased cortisol levels in fish of the BN-treated groups. Histological examinations of the anterior and posterior intestines and liver in groups B1.5 and B3 revealed the healthiest organs. This study recommends BN at a concentration of 1.5% as a feed additive in the Dicentrarchus labrax diet.

Application of nZnO supported with nanoclay for improving shrimp immunity

This study discloses the nanoscale silicate platelet-supported nZnO (ZnONSP) applied as novel feed additives in aquaculture. The preparation of the nanohybrid (ZnO/NSP = 15/85, w/w) was characterized by UV-visible spectroscopy, powder X-ray diffraction and transmission electron microscope. The effects of ZnONSP on growth, zinc accumulation, stress response, immunity and resistance to Vibrio alginolyticus in white shrimp (Penaeus vannamei) were \demonstrated. To evaluate the safety of ZnONSP, shrimps (2.0 ± 0.3 g) were fed with ZnONSP containing diets (200, 400 and 800 mg/kg) for 56 days. Dietary ZnONSP did not affect the weight gain, specific growth rate, feed conversion ratio, survival rate, zinc accumulation, and the expression of heat shock protein 70 in tested shrimps. To examine the immunomodulatory effect of ZnONSP, shrimps (16.6 ± 2.4 g) were fed with the same experimental diets for 28 days. Dietary ZnONSP improved the immune responses of haemocyte in tested shrimps, including phagocytic rate, phagocytic index, respiratory burst, and phenoloxidase activity, and upregulated the expression of several genes, including lipopolysaccharide, β-1,3-glucan binding protein, peroxinectin, penaeidin 2/3/4, lysozyme, crustin, anti-lipopolysaccharide factor, superoxide dismutase, glutathione peroxidase, clotting protein and α-2-macroglobulin. In the challenge experiment, shrimps (17.2 ± 1.8 g) were fed with ZnONSP containing diets (400 and 800 mg/kg) for 7 days and then infected with Vibrio alginolyticus. Notably, white shrimps that received ZnONSP (800 mg/kg) showed significantly improved Vibrio resistance, with a survival rate of 71.4 % at the end of 7-day observation. In conclusion, this study discovers that ZnONSP is a new type of immunomodulatory supplement that are effective on enhancing innate cellular and humoral immunities, and disease resistance in white shrimp.

Optimal dietary zinc inclusion improved growth performance, serum antioxidant capacity, immune status, and liver lipid and glucose metabolism of largemouth bass (Micropterus salmoides)

This study was conducted to ascertain the effect of dietary Zn on growth and health status of juvenile largemouth bass (Micropterus salmoides). Six experimental diets with Zn level of 50.17, 56.74, 73.34, 86.03, 123.94, and 209.20 mg/kg, respectively were compounded using complex amino acid-chelated zinc, and were fed to juvenile fish (5.50 ± 0.10 g) for 70 d. The specific growth rate (SGR) varied with dietary Zn level in a quadratic model and peaked at the 73.34 mg/kg group, while the feeding rate exhibited an opposite trend (P < 0.05). The condition factor, hepatosomatic index and mesenteric fat index all exhibited a tendency similar with SGR (P < 0.05). Dietary Zn level affected serum total proteins, urea, triglycerides, and glucose (P < 0.05). Serum Zn and copper levels linearly increased with dietary Zn level, while serum iron and manganese showed the opposite trend. Serum superoxide dismutase (SOD) and total antioxidant capacity (T-AOC) increased with dietary Zn level and reached a plateau at 86.03 mg/kg. Serum complement component 3 (C3), IgM, and lysozyme also were enhanced by 73.34 mg/kg Zn. Body protein content increased with zinc level up to 73.34 mg/kg, and then remained steadily. As dietary Zn level increased, hepatic lipid level increased and then reached a plateau at 86.03 mg/kg group, while glycogen increased linearly. Moreover, gene expression related to lipid and glycogen metabolism from liver transcriptome further explained the liver lipid and glycogen variations. To conclude, a dietary Zn requirement of 76.99 mg/kg was suggested for juvenile largemouth bass to improve growth, antioxidant capacity, and immune status.

Mitigating abiotic stresses using natural and modified stilbites synergizing with changes in oxidative stress markers in aquaculture

In-depth mineralogical understanding and characterization are necessary to explore potential applications of clinoptilolites. In this study, the clinoptilolite collected from quarries and identified as stilbite microscopically and spectroscopically was subjected to physical and chemical treatments for the synthesis of modified stilbites, which were further evaluated for determining their removal efficiencies on ammonical contaminant in a predetermined concentration range from various source of aquaculture water namely fish pond, aquaponics and ornamental under laboratory condition. High-resolution transmission electron microscope results revealed that stilbite was rod-shaped in all forms but physically modified stilbite contains some nano-zeolite particles, synthesized probably due to heat treatment. The natural zeolite (stilbite) and microwave sodium acetate treated stilbite were found to be most effective in ammonia removal, hence both these products were further evaluated for the removal of cadmium and lead under laboratory conditions and for the ammonia removal in fish pond water under wet lab conditions. The results showed that these zeolites at 10-100 mg/L and 100-200 mg/L had a better removal efficiency of ammonical and metallic contaminants, respectively. Fish samples were taken at particular intervals to determine oxidative stress parameters, i.e., superoxide dismutase and catalase enzyme activities were found to be increased in control fish samples without treatment due to abiotic stress caused by higher ammonia concentration. The levels of oxidative stress markers are decreased in the treatments with zeolite-stilbite which brings to light its potential efficiency in alleviating stress in fish. This study revealed the potential of natural and abundantly available native zeolite-stilbite and its chemically modified form in relieving ammonical stress from the aquaculture system. This work has potential applications for the environmental management of aquaculture, ornamental fisheries, and aquaponics.

Immunomulation effect of alginic acid and chitooligosaccharides in silver carp (Hypophthalmichthys molitrix)

Individual and combined efficacy of chitooligosaccharides (COS) and alginic acid (AA) at 1 g, 2 g, and 3 g per kg diet was assessed on growth and disease resistance in silver carp (Hypophthalmichthys molitrix) against Edwardsiella ictaluri. Growth parameters including specific growth rate (SGR), weight gain (WG), and feed conversion rate (FCR) were significant in fish fed 2 g and 3 g kg^-1 of COS or AA, and fish fed combined COS + AA at 1, 2 and 3 kg^-1 diet. In all groups, the survival rate (SR) was recorded 100%, except in group fed 2 g kg^-1 AA diet. All the hematological and biochemical profiles significantly increased in groups fed 2 g and 3 g kg^-1 of COS, AA, and COS + AA diets. Lipase and amylase enzyme activities and superoxide dismutase (SOD), malondialdehyde (MDA), glutathione peroxidase (GPx) antioxidant enzyme activities were significantly increased in fish fed 2 g and 3 g kg^-1 of COS, AA, and COS + AA diet. Respiratory burst (RB), lysozyme (Lyz), reactive oxygen species (ROS) activities, and immunoglobuline (Ig) level were enhanced significantly in fish fed 2 g kg^-1 of COS or COS + AA and all 3 g kg^-1 diets, whereas nitric acid (NO) production and serum AP activity were improved in 2 g kg^-1 COS + AA and 3 g kg^-1 COS or COS + AA diets. Pro-inflammatory cytokine such as IL-8 mRNA transcriptions was significant in 2 g kg^-1 COS + AA diet and all 3 g kg^-1 diet. The IL-10 anti-inflammatory cytokine mRNA transcriptions were significant in 3 g kg^-1 COS or COS + AA diets. This study was confirmed that H. molitrix fed with 3 g kg^-1 COS or COS + AA diets were better activity when compared to other diet.

Zeolite mediated processing of nitrogenous waste in the rearing environment influences gut and sediment microbial community in freshwater crayfish (Cherax cainii) culture

Zeolite is known to uptake toxic metals and filter nitrogenous waste from aquaculture effluents. The present study aimed to investigate the impacts of zeolite in three different applications namely, dietary zeolite (DZ), suspended zeolite (SZ) in the water column, and a combination of both (DZSZ) relative to unexposed freshwater crayfish, marron (control). At the end of the 56-days trial, the impact was assessed in terms of characterization of microbial communities in the culture environment and the intestine of marron. Alongside the microbial communities, the innate immune response of marron was also evaluated. The 16S rRNA data showed that marrons exposed to the suspended zeolite had a significant increase of bacterial diversity in the gut, including the restoration of marron core operational taxonomic units (OTUs), relative to other forms of exposures (DZ, DZSZ) and the control. Suspended zeolite alone also increased the number of unshared OTUs and genera, and improved predicted metabolic functions for the biosynthesis and digestion of proteins, amino acids, fatty acids, and hormones. In the tank sediment, the shift of microbial communities was connected more strongly with the time of experiment than the type of zeolite exposure. In the second case, only control marron had a different microbial ordination in terms of rare taxa present in the community. Nevertheless, the modulation in the gut environment was found more prominent in DZ, relative to modulation in the tank sediments. The taxa-environment correlation identified Rhodoferax as the most potential bacteria in removing nitrogenous waste from the rearing environment. Further analysis showed that SZ resulted in the upregulation of genes associated with the innate immune response of marron. Overall results suggest that SZ can be used to enrich microbial communities in the gut and tank sediments and better immune performance of marron.

Blood Performance: A New Formula for Fish Growth and Health

Simple Summary

The use of haematological and blood biochemistry parameters has proven to be effective and repeatable ways to monitor fish health. Testing these parameters is becoming more common in aquaculture studies. Further, it is widely accepted that fish with better health status are more likely to grow faster as less energy should be consumed for non-growth purposes. Here, a new formula (Blood Performance) is introduced, which contains five common haematological and blood biochemistry parameters: red blood cells, white blood cells, haemoglobin, haematocrit, and total protein. The idea behind this formula is that any single component of this formula cannot be reliable enough as a biomarker of fish health and growth. However, interestingly, Blood Performance can be much more reliable and accurate for monitoring fish health and growth.

Abstract

Monitoring fish health in a repeatable and accurate manner can contribute to the profitability and sustainability of aquaculture. Haematological and blood biochemistry parameters have been powerful tools and becoming increasingly common in aquaculture studies. Fish growth is closely related to its health status. A fish with a higher growth rate is more likely to be a healthy one. Any change in the physiological status of the fish, from pollution to nutritional stress, can cause changes in the blood parameters. Various aquaculture studies have measured the following components: red blood cells, white blood cells, haemoglobin, haematocrit, and total protein. However, because these parameters do not always follow the same trend across experimental fish, it is difficult to draw a firm conclusion about which parameter should be considered. Therefore, Blood Performance (BP) as a new formula is introduced, which is a more reliable indicator. This formula is simple and sums up the natural logarithm of the five above-mentioned parameters. More than 90 published peer-reviewed articles that measured these five parameters in the last six years confirmed the reliability and validity of this formula. Regardless of which supplements were added to the diets, the fish with a higher growth rate had higher BP as well. In addition, in 44 studies out of 53 articles, there was a significant positive correlation between specific growth rate and BP. Under different stressful situations, from pollution to thermal stress, the fish under stress had a lower BP than the control. Fish meal and fish oil replacement studies were further evidence for this formula and showed that adding excessive alternative proteins decreased growth along with BP. In conclusion, BP can be a reliable indicator of fish health and growth when it is compared between groups in the same experiment or farm. Although there was a positive correlation between specific growth rate and BP, comparing BP between experiments is not recommended. Standardising the haematological assays can improve the reliability and accuracy of BP across experiments.

Impact of Hygrophila auriculata supplementary diets on the growth, survival, biochemical and haematological parameters in fingerlings of freshwater fish Cirrhinus mrigala (Hamilton, 1822)

The present study investigates the effects of Supplementary diet Hygrophila auriculata on the growth, survival, biochemical and haematological parameters of Cirrhinus mrigala. The seaweed was administered to the fish possessing an initial average weight of 14.063 ± 1.828 g. Fish were fed with supplementary diet H. auriculata exhibited significant difference (P < 0.05) in the growth performance, haematological indices such as RBC count, haematocrit volume, haemoglobin, WBC, MCV, MCH and MCHC concentration in contrast to the control after a period of 8 weeks. Also, there were significant differences in biochemical parameters (P < 0.05), between the fish supplemented with dietary H. auriculata extract and the control group. These findings suggest that the administration of H. auriculata extract has a positive effect on the immunological indices and the immune system activity in Mrigal fish.

The effects of dietary clinoptilolite and chitosan nanoparticles on growth, body composition, haemato-biochemical parameters, immune responses, and antioxidative status of Nile tilapia exposed to imidacloprid

This study aimed at the evaluation of the mitigating effects of dietary zeolites (ZEO) and/or chitosan nanoparticle (ChNP) on imidacloprid (IMID)-induced toxicity in Nile tilapia (Oreochromis niloticus). Fish (18.03 ± 0.01 g) were allocated into six groups; one fed on a basal diet (control) (CTR), and the other groups were fed diets supplemented with ChNPs (5 g kg^-1) and/or ZEO (20 and 40 g kg^-1) (ZEO₂₀ and ZEO₄₀) for 60 days. In the last 14 days of the experiment, all groups were exposed to a sub-lethal dose of IMID (½ of 96 h LC₅₀ = 0.0545 μg L^-1). Dietary ZEO₂₀ significantly improved all growth parameters (P ˂ 0.05), while ChNPs had no significant effects. The crude protein of the fish body was significantly increased in all groups compared to the CTR (P ˂ 0.05). No significant impacts of ChNPs, ZEO, and their interaction (P > 0.05) were noticed on the moisture, dry matter, and ash percentages. Compared to the CTR, hematocrit values were significantly decreased (P ˂ 0.05) in ChNP and ZEO₂₀ groups; meanwhile, their levels were significantly increased (P ˂ 0.05) in the ZEO₄₀ group and all combined treatments. Fish fed diets with ChNPs and/or ZEO had significant increments in the MCV values (P ˂ 0.05). Moreover, fish fed diets supplemented with ChNPs or their combination with ZEO had the lowest glucose and alkaline phosphatase levels compared with the CTR. Serum aspartate transferase levels were significantly decreased in all treated groups (P ˂ 0.05) compared to the CTR. ChNPs alone or combined with ZEO significantly exhibited the highest lysozyme and nitro blue tetrazolium values (P ˂ 0.05). On the other hand, fish in the CTR group had the highest malondialdehyde and lowest nitric oxide levels compared to the other groups. Interestingly, the lowest IMID residues in fish flesh were found in fish groups fed diet with a combination of ZEO and ChNPs. Partial or complete protection of the hepatic and splenic tissues were observed in fish group with combined treatment with ChNPs and ZEO. In conclusion, the application of ZEO and/or ChNPs in Nile tilapia diets looks to be a leading approach to mitigate the toxic impacts of IMID.

Dietary Azomite, a natural trace mineral complex, improved the growth, immunity response, intestine health and resistance against bacterial infection in largemouth bass (Micropterus salmoides)

Azomite is a hydrated calcium sodium aluminosilicat rich in rare earth elements. To investigate the dietary effects of Azomite on growth, intestine microbiota and morphology, immunohematological changes and disease resistance, seven diets with Azomite supplementation of 0 (the control), 1.0, 2.0, 3.0, 4.0, 5.0 and 6.0 g/kg (A0, A1, A2, A3, A4, A5, A6), were prepared and fed to largemouth bass, Micropterus salmoides (7.96 ± 0.19) for 60 days. The results revealed that the weight gain (WG) increased first and then decreased with the increasing dietary Azomite, and the A2 group presented the highest WG and lowest feed conversion ratio among all the groups. The supplementation of 2.0 g/kg Azomite significantly increased the intestine protease activity, the crude protein of whole body and protein retention (P < 0.05), and high inclusion of Azomite (6.0 g/kg) significantly reduced the lipid retention (P < 0.05). The amounts of red blood cells in A5, A6 groups, white blood cells in A3, A5, A6 groups and lymphocyte in A2-A6 groups were all significantly higher than those in the control group (P < 0.05). In addition, serum superoxide dismutase and catalase activities in A5, A6 groups, and serum alkaline phosphatase and lysozyme activities in A2-A4 groups showed significantly higher values than the control group (P < 0.05). Intestinal microbiota analysis indicated that the Tenericutes abundance was increased, whereas Proteobacteria abundance was decreased in all Azomite supplemented groups. The villus height in A2-A4 groups, and the villus width in A2 group were significantly higher than those of the control group (P < 0.05). The cumulative mortality was reduced by the addition of 2.0-5.0 g/kg Azomite after challenging with A. hydrophila (P < 0.05). In conclusion, proper addition of Azomite in diets improved the growth, intestine morphology, immune response and disease resistance in largemouth bass, and the optimal inclusion was estimated to be 2.0-3.0 g/kg diet.

Dietary montmorillonite as growth promoter and immunomodulator in rainbow trout (Oncorhynchus mykiss)

A 98-day research was conducted to assess the influence of dietary montmorillonite (MMT) on growth and immune competence in rainbow trout (Oncorhynchus mykiss). Fish fry (mean weight: 500 ± 35 mg) were fed with four experimental diets contained MMT at levels of 0 (as control group), 1, 2 and 4%. At the end of the experiment, the survival rate and growth parameters and serum total protein and albumin levels in MMT experimental groups was higher than the control group. Regarding humoral immune responses, fish being fed with 2 and 4% MMT diets showed the greatest and the lowest serum C₃, C₄ and lysozyme levels, respectively. Serum alternative complement pathway activity (ACH50) in groups fed with 1 and 2% MMT supplemented diets was higher than the other groups. At the end of the challenge test with VHSV, the mortality rate reached to 28 and 20% in the control group and 4% MMT supplemented groups, respectively, whereas fish fed with 1 and 2% MMT supplemented diets showed the lowest mortality rate (2.5%) Fish fed with 1 and 2% MMT supplemented groups showed higher head kidney IL-1β and TNF-α genes expression compared to the other treatment groups. In addition, fish fed with 2% MMT-supplemented diet had the highest head kidney Lyz-2 gene expression. In summary, the results of this research suggests that supplementing diet with MMT at 1 or 2% improve growth and non-specific humoral immune responses and induce head kidney immune relate genes expression and disease resistance against VHS in O. mykiss.

Effects of dietary chitosan and nano-chitosan loaded clinoptilolite on growth and immune responses of rainbow trout (Oncorhynchus mykiss)

In this study, rainbow trout Oncorhynchus mykiss weighing 27.75 ± 0.34 g were orally subjected to eight experimental diets each in three replicates containing varying amounts of chitosan and nano-chitosan (0.05, 0.5 and 5 g kg^-1) loaded in clinoptilolite (14.28 g kg^-1) for 70 days; and the growth and immune responses were evaluated. Results showed that growth parameters in fish fed diets chit + clin2, chit + clin3, nchit + clin1, nchit + clin2 and nchit + clin3 were significantly higher than in fish fed the control diet. All feeds, except chit + clin3, and nchit + clin3, significantly increased the total protein level. Feeds containing chit + clin2, nchit + clin1, and nchit + clin2 significantly elevated serum lysozyme activity compared with the control group. All treatments, except chit + clin3, and nchit + clin3 exhibited higher serum immunoglobulin (Ig) level than control one. In contrast, diet nchit + clin1 significantly unregulated the expression of Ig M gene in fish head-kidney compared to other groups. Additionally, all feeds, except clinoptilolite, and nchit + clin3, significantly improved the serum complement activity. Diets chit + clin2, nchit + clin1, and nchit + clin2 also significantly elevated antibacterial activity against Yersinia ruckeri compared with the control diet. Expression of inducible nitric oxide synthase (iNOS) gene in fish fed diets clinoptilolite, chit + clin1, chit + clin3, nchit + clin1, nchit + clin2, and nchit + clin3 was significantly higher than the control diet. All diets, except clinoptilolite, increased IL-1β gene expression compared to the control group. Present results suggest that diets supplemented with nchit + clin, especially at 0.05 g kg^-1 nano-chitosan inclusion, could improve growth performance and immune parameters of rainbow trout.

Protective efficacy of Shilajit enriched diet on growth performance and immune resistance against Aeromonas hydrophila in Oreochromis mossambicus

We investigated the effects of dietary enriched with Shilajit in three dose levels: 2.0, 4.0, and 6.0 g kg^-1 in the basal diet on growth rate, non-specific immune response, and disease resistance for 60 days in Oreochromis mossambicus against an opportunist pathogen, Aeromonas hydrophila. The results showed that the Shilajit enriched diets at 4.0 and 6.0 g kg^-1 diets significantly (p < 0.05) enhance survival rate, weight gain (WG), protein efficiency ratio (PER), specific growth rate (SGR), and feed efficiency (FE), whereas it significantly decrease the feed conversion ratio (FCR) from weeks 1-4 when compared with control. The innate immune parameters, such as the phagocytic, complement, respiratory burst, and lysosome activities in infected fish fed with all Shilajit enriched diet were significantly (p < 0.05) enhances on weeks 2-4. A very low cumulative mortality, 8.0% and 12.0% were observed in the infected fish fed with 4.0 and 6.0 g kg^-1 Shilajit enriched diets, whereas 18% mortality was found with 2 g kg^-1 diet. In conclusion, 4.0 and 6.0 g kg^-1 Shilajit enriched diets significantly increased the growth performance, innate immune response, and disease resistance in O. mossambicus against A. hydrophila infection.

Kaolin incorporated diet on growth and immune response in Ctenopharyngodon idellus against Aeromonas hydrophila

The effect of kaolin enriched diet on growth, hematology, and immune response in the grass carp Ctenopharyngodon idellus against Aeromonas hydrophila is reported. Both the infected and uninfected groups fed with kaolin enriched diet gained better weight, protein efficiency ratio (PER) and feed conversion ratio (FCR). The survival rate was 98.3% in control (C) and uninfected (UI) fed with 2 g kg^-1 kaolin diet, whereas it was 95.0% in uninfected (UI) fed with 1 g kg^-1 or infected (I) fed with 1 g kg^-1 kaolin diets. In both groups the red blood cell (RBC) and white blood cell (WBC) counts, percentage of lymphocytes and eosinophils, level of albumin and globulin increased in uninfected (UI) fed with 1, 2, and 3 g kg^-1 diets. The serum Ig level significantly increased in both groups when fed with 3 g kg^-1 diet, whereas the phagocytic activity did not increase significantly. Further the respiratory burst activity in both groups significantly increased with any supplemented diet. The serum superoxide dismutase (SOD) activity increased significantly in the infected group fed with 2 g kg^-1 diet and the uninfected group fed with 1 g kg^-1 diet. The complement activity was significantly enhanced in both groups when fed with 1 and 2 g kg^-1 diets; the lysozyme activity increased with 2 g kg^-1 diet; besides the group was 5% mortality whereas 10% mortality was observed when fed with 1 or 3 g kg^-1 diets. The present results suggest that C. idellus fed with kaolin enriched diet promotes growth, hematology, innate and adaptive immune response against Aeromonas hydrophila infection.

Bentonite clay supplemented diet on immunity in stinging catfish, Heteropneustes fossilis against Aeromonas hydrophila

The effect of Sodium Bentonite (SB) enriched diet on growth performance, innate immune response, and disease resistance in stinging catfish, Heteropneustes fossilis against Aeromonas hydrophila is reported. The infected fish fed with 5% SB had the maximum weight gain diet (PWG %) and specific growth rate (SGR %) were 26% and 29% when compared to 14% and 17% with 10% diet. Similarly the phagocytic activity increased significantly when infected fish were fed with 5% or 10% SB diets during the experimental period; the complement, respiratory burst and lysozyme activities were also significantly enhanced on weeks 2 and 4. The lower cumulative mortality (10% and 15%) was observed when the infected fish were fed with 5% and 10% SB diets for 30 days. The results suggest that the infected H. fossilis after administration of 5% and 10% SB enriched diets for 30 days had significantly improved growth performance, innate immunity, and disease resistance against A. hydrophilla. Hence, sodium bentonite can be used as a feed additive to stimulate immunity and for disease resistance in the effective production of economically valuable freshwater catfish, H. fossilis.

Modulation of the innate immune responses in the striped snakehead murrel, Channa striata upon experimental infection with live and heat killed Aeromonas hydrophila

It is well-known that the innate immune mechanisms in fish serve as the first line of defence against wide variety of pathogens. In most of the situations, innate responses get induced and enhanced after the pathogen invasion. It would be interesting to look into the inducibility of various innate immune mechanisms and the level of enhancement after infection with the pathogen. Hence, in the present investigation, modulation of the innate immune responses in the striped snakehead murrel, Channa striata on experimental challenge with either live virulent or heat killed Aeromonas hydrophila at a dose of 1x107 CFU (suspended in 0.2 mL PBS) were measured. Most of the non-specific (both humoral and cellular) immune responses tested were substantially induced or enhanced in both the experimental groups in comparison with the unchallenged control group. Significant increase in the lysozyme, total peroxidase, antiprotease and respiratory burst activities were observed after the pathogen challenge. Thus, most of the innate non-specific immune responses are inducible though they are constitutive of fish immune system exhibiting a basal level of activity even in the absence of pathogen challenge.

Valorisation of post-sorption materials: Opportunities, strategies, and challenges

Adsorption is a facile, economic, eco-friendly and low-energy requiring technology that aims to separate diverse compounds (ions and molecules) from one phase to another using a wide variety of adsorbent materials. To date, this technology has been used most often for removal/recovery of pollutants from aqueous solutions; however, emerging post-sorption technologies are now enabling the manufacture of value-added key adsorption products that can subsequently be used for (i) fertilizers, (ii) catalysis, (iii) carbonaceous metal nanoparticle synthesis, (iv) feed additives, and (v) biologically active compounds. These new strategies ensure the sustainable valorisation of post-sorption materials as an economically viable alternative to the engineering of other green chemical products because of the ecological affability, biocompatibility, and widespread accessibility of post-sorption materials. Fertilizers and feed additives manufactured using sorption technology contain elements such as N, P, Cu, Mn, and Zn, which improve soil fertility and provide essential nutrients to animals and humans. This green and effective approach to managing post-sorption materials is an important step in reaching the global goals of sustainability and healthy human nutrition. Post-sorbents have also been utilized for the harvesting of metal nanoparticles via modern catalytic pyrolysis techniques. The resulting materials exhibited a high surface area (>1000m²/g) and are further used as catalysts and adsorbents. Together with the above possibilities, energy production from post-sorbents is under exploration. Many of the vital 3E (energy, environment, and economy) problems can be addressed using post-sorption materials. In this review, we summarize a new generation of applications of post-adsorbents as value-added green chemical products. At the end of each section, scientific challenges, further opportunities, and issues related to toxicity are discussed. We believe this critical evaluation not only delivers essential contextual information to researchers in the field but also stimulates new ideas and applications to further advance post-sorbent applications.