Comparative Effect of Chemical and Green Zinc Nanoparticles on the Growth, Hematology, Serum Biochemical, Antioxidant Parameters, and Immunity in Serum and Mucus of Goldfish, Carassius auratus (Linnaeus, 1758).

Recently, nano feed supplement research has great attention to improving healthy aquatic production and improving the aquatic environment. With the aims of the present study, chemical and green synthesized nanoparticles are characterized by various instrumentation analyses, namely UV-Vis spectrophotometry (UV-Vis), X-ray diffraction (XRD), Fourier transform infra-red (FTIR) spectroscopy, and scanning electron microscope (SEM). After characterization analysis of these nanoparticles utilized in aquatic animals, the composition ratio is as follows: controls (without ZnO-NPs (0 mg/L)), T1 (0.9 mg/L ZnO-NPs), T2 (1.9 mg/L ZnO-NPs), T3 (0.9 mg/L GZnO-NPs), T4 (1.9 mg/L GZnO-NPs). SEM investigation report demonstrates that the structure of the surface of green synthesized zinc oxide nanoparticles (GZnO-NPs) was conical shape and the size ranging was from 60 to 70 nm. Concerning hematological parameters, the quantity of hemoglobin increased in different doses of green zinc nanoparticles, but the values of MCV and MCH decreased somewhat. However, this decrease was the highest in the T2 group. Total protein and albumin decreased in T2 and triglyceride, cholesterol, glucose, cortisol, creatinine, and urea increased, while in T3 and T4 groups, changes in biochemical parameters were evaluated as positive. Mucosal and serum immunological parameters in the T2 group showed a significant decrease compared to other groups. In zinc nanoparticles, with increasing dose, oxidative damage is aggravated, so in the T2 group, a decrease in antioxidant enzymes and an increase in MDA were seen compared to other groups. In this regard, the concentration of liver enzymes AST and ALT increased in the T2 group compared with control and other groups. This can confirm liver damage in this dose compared with control and other groups. This research work suggests that green synthesized form of zinc nanoparticles in higher doses have less toxic effects in comparison to the chemical form of zinc nanoparticles and can act as suitable nutrient supplements in aquatic animals.

Seaweed and Seaweed-Based Functional Metabolites as Potential Modulators of Growth, Immune and Antioxidant Responses, and Gut Microbiota in Fish.

Seaweed, also known as macroalgae, represents a vast resource that can be categorized into three taxonomic groups: Rhodophyta (red), Chlorophyta (green), and Phaeophyceae (brown). They are a good source of essential nutrients such as proteins, minerals, vitamins, and omega-3 fatty acids. Seaweed also contains a wide range of functional metabolites, including polyphenols, polysaccharides, and pigments. This study comprehensively discusses seaweed and seaweed-derived metabolites and their potential as a functional feed ingredient in aquafeed for aquaculture production. Past research has discussed the nutritional role of seaweed in promoting the growth performance of fish, but their effects on immune response and gut health in fish have received considerably less attention in the published literature. Existing research, however, has demonstrated that dietary seaweed and seaweed-based metabolite supplementation positively impact the antioxidant status, disease resistance, and stress response in fish. Additionally, seaweed supplementation can promote the growth of beneficial bacteria and inhibit the proliferation of harmful bacteria, thereby improving gut health and nutrient absorption in fish. Nevertheless, an important balance remains between dietary seaweed inclusion level and the resultant metabolic alteration in fish. This review highlights the current state of knowledge and the associated importance of continued research endeavors regarding seaweed and seaweed-based functional metabolites as potential modulators of growth, immune and antioxidant response, and gut microbiota composition in fish.

Bioaccumulation and Bioremediation of Heavy Metals in Fishes-A Review.

Heavy metals, the most potent contaminants of the environment, are discharged into the aquatic ecosystems through the effluents of several industries, resulting in serious aquatic pollution. This type of severe heavy metal contamination in aquaculture systems has attracted great attention throughout the world. These toxic heavy metals are transmitted into the food chain through their bioaccumulation in different tissues of aquatic species and have aroused serious public health concerns. Heavy metal toxicity negatively affects the growth, reproduction, and physiology of fish, which is threatening the sustainable development of the aquaculture sector. Recently, several techniques, such as adsorption, physio-biochemical, molecular, and phytoremediation mechanisms have been successfully applied to reduce the toxicants in the environment. Microorganisms, especially several bacterial species, play a key role in this bioremediation process. In this context, the present review summarizes the bioaccumulation of different heavy metals into fishes, their toxic effects, and possible bioremediation techniques to protect the fishes from heavy metal contamination. Additionally, this paper discusses existing strategies to bioremediate heavy metals from aquatic ecosystems and the scope of genetic and molecular approaches for the effective bioremediation of heavy metals.

Vitamin E supplementation in diet ameliorates growth of Nile tilapia by upgrading muscle health.

Vitamin E (VE), an important lipid-soluble antioxidant, has great influence on growth and maintenance in animal. The effects of VE supplemented diet on growth and feed usage in Nile tilapia (Oreochromis niloticus) was investigated in this study. Three formulated diets containing VE (0, 50 and 100 mg/kg) were fed to Nile tilapia (3.56 ± 0.16 g) in glass aquaria maintaining three replicate groups for 56 days (8 weeks). Survival, growth performance including weight gain, percent weight gain, and specific growth rate (WG, % WG, and SGR), and feed utilization comprising protein efficiency ratio and feed conversion ratio (PER and FCR) were calculated. Hemato-biochemical indices including hemoglobin level (Hb), white blood cell (WBC), red blood cell (RBC) and glucose level were analyzed. In addition, muscle morphology was examined after completion of the experiment. At the end of the trial, WG, %WG, SGR, FCR and PER increased significantly which had dietary VE supplimentation. However, no distinct changes were observed in Hb level, RBC count, WBC count and glucose level among these different dietary groups. Dietary VE treatments significantly upgraded the muscle fiber diameter and lowered the intra-muscle gap. Moreover, quantity of hyperplastic muscle fiber as well as nucleus also significantly enhanced by VE. Morphological structure of muscle characterized by a huge proportion of hyperplastic muscle that may be supposed to contribute the enhanced growth of Nile tilapia receiving VE supplemented diet. Therefore these results suggested that VE incorporation into the feed can be effective to improve the feed efficiency and maximize the growth of O. niloticus.

Impacts of heavy metals on early development, growth and reproduction of fish - A review.

Heavy metals pollution causes a threat to the aquatic environment and to its inhabitants when their concentrations exceed safe limits. Heavy metals cause toxicity in fish due to their non-biodegradable properties and their long persistence in the environment. This review investigated the effects of heavy metals on early development, growth and reproduction of fish. Fish embryos/larvae and each developmental stage of embryo respond differently to the intoxication and vary from species to species, types of metals and their mode of actions, concentration of heavy metals and their exposure time. Many of the heavy metals are considered as essential nutrient elements that positively improve the growth and feed utilization of fishes but upon crossing the maximum tolerable limit these metals cause not only a hazard to fish health but also to human consumers and the disruption of ecological systems. Reduced gonadosomatic index (GSI), fecundity, hatching rate, fertilization success, abnormal shape of reproductive organs, and finally failure of reproduction in fish have been attributed to heavy metal toxicity. In summary, this review sheds light on the manipulation of fish physiology by heavy metals and seeks to raise sensitivity to the prevention and control of aquatic environmental contamination, particularly from heavy metals.

Evaluation of Heavy Metal Contamination in Some Selected Commercial Fish Feeds Used in Bangladesh.

Quality fish feed is the prime need for successful aquaculture. Feed qualities determine the fish flesh quality including appearance, color, odor, flavor, texture, nutritive value, and shelf-life. Nowadays, consumers are very much concerned about various issues regarding way of fish farming, types of feed ingredients used etc. The current study was conducted to assess the heavy metal contents and nutritional composition of some selected commercial fish feeds used in Bangladesh. The major heavy metal concentrations and proximate composition (moisture, crude protein, crude lipid, ash, crude fiber, and carbohydrate) of the collected feed samples were analyzed. The results showed that the feeds contained a number of heavy metals in varying proportions. The highest concentrations (mg/kg) of heavy metals such as lead (Pb), cadmium (Cd), chromium (Cr), copper (Cu), and zinc (Zn) analyzed in fish feed samples were 0.189, 0.027, 1.023, 0.303, and 1.468, respectively. There were significant differences between the nutritive values provided by feed companies and the values observed in this finding. The present study recommends that adequate measures are required to be taken by commercial fish feed manufacturers to ensure the nutritional quality of feed as well as to avoid the contamination of feed from heavy metals. Otherwise, fish and human, the ultimate consumer, may be predisposed to the assimilation and accumulation of the assessed heavy metals.

Probiotics, prebiotics and synbiotics improved the functionality of aquafeed: Upgrading growth, reproduction, immunity and disease resistance in fish.

Aquaculture plays an increasingly significant role in improving the sustainability of global fish production. This sector has been intensified with the advent of new husbandry practices and the development of new technology. However, the increasing intensification and indiscriminate commercialized farming has enhanced the vulnerability of cultivated aquatic species to damage from pathogens. In efforts to confront these various diseases, frequent use of drugs, antibiotics, chemotherapeutics, and agents for sterilization have unintentionally added to the risk of transmission of pathogens and harmful chemical compounds to consumers. Some natural dietary supplements are believed to have the potential to offset this setback in aquaculture. Application of bio-friendly feed additives such as probiotics, prebiotics and synbiotics are becoming popular dietary supplements with the potential to not only improve growth performance, but in some cases can also enhance immune competence and the overall well-being of fish and crustaceans. The present review discusses and summarizes the effects of probiotics, prebiotics and synbiotics application on growth, stress mitigation, microbial composition of intestine, immune system and health condition of aquatic animals in association with existing constraints and future perspectives in aquaculture.

Dietary Zinc in Association with Vitamin E Promotes Growth Performance of Nile Tilapia.

Zinc (Zn) and vitamin E (VE) are essential micro-nutrients that contribute a pivotal role in the physiology and nutrition of fish. An experiment was designed to know the effects of Zn and VE addition in the diet on growth and feed utilization in Nile tilapia (Oreochromis niloticus). Four diets containing Zn (80 mg/kg), VE (50 mg/kg), Zn (80 mg/kg) + VE (50 mg/kg), and without Zn and VE (control) were fed to Nile tilapia in aquaria with triplicate groups for 6 weeks. Survival, growth parameters (weight gain, WG; %WG; specific growth rate, SGR), and feed utilization (protein efficiency ratio, PER; feed conversion ratio, FCR) were calculated at the end of the feeding trial. Several hemato-biochemical parameters (hemoglobin, Hb; red blood cell, RBC; white blood cell, WBC, and glucose) and morphology of muscle were analyzed. The growth parameters (WG, %WG, and SGR) and feed utilization (FCR and PER) improved significantly in the fish fed with Zn, VE, and Zn + VE supplemented diets. There was no significant change in the values of Hb, RBC, WBC, and glucose level among different groups. Significantly improved diameter of muscle fiber, reduced distance between muscle fiber, and increased number of the nucleus and hyperplastic muscle fiber were observed in the fish fed with Zn, VE, and Zn + VE supplemented diets. These results suggested that Zn and VE can be effectively incorporated into the diets of Nile tilapia for better growth with maximum feed utilization.

Assessment of heavy metals in farmed shrimp, Penaeus monodon sampled from Khulna, Bangladesh: An inimical to food safety aspects.

The analytical experiment was executed to present detailed reports on the concentration of heavy metals (nickel, iron, zinc, manganese, chromium, lead, and cadmium) in farmed shrimp, Penaeus monodon and its concomitant human health risks upon consumption. A total of 147 farms from six sub-districts of Khulna were selected for sample collection and concentration of heavy metals were determined by Atomic Absorption Spectrometry (AAS) method, following electro-thermal heater digestion. Ni and Cr were found considerably below the detectable limit (BDL) in four sub-districts, while Cr found in shrimps from Rupsa and Paikgacha were far higher than the maximum recommended limit defined by FAO and WHO. The average concentrations of Fe and Mn in all sub-districts crossed the recommendations, whereas average concentrations of Zn, Ni, Cd, and Pb were within the recommendations. Regardless of sampling site, target hazard quotients (THQ) of more than 1 contributed by Fe confirmed higher level of hazard index (HI), indicating potential human health risk. Fortunately, no heavy metal or their additive effect found to offer lifetime potency of carcinogenesis upon consumption of these shrimps. Therefore, probabilistic non-carcinogenic human health risk from Fe contamination necessitates stringent monitoring and controlling of this metal from different sources to farms.

Chromium Supplementation in Diet Enhances Growth and Feed Utilization of Striped Catfish (Pangasianodon hypophthalmus).

Chromium (Cr) is a trace element and plays a significant role in fish nutrition and physiology. An experiment was designed to know the effects of Cr addition in the diets to growth and feed utilization in striped catfish (Pangasianodon hypophthalmus). Four diets with Cr (0, 2, 4, and 8 mg kg-1) were fed to striped catfish in aquaria with triplicate groups for 60 days. Survival, growth parameters (weight gain, WG; %WG; specific growth rate, SGR), and feed utilization (feed intake, FI; feed efficiency, FE; protein efficiency ratio, PER; feed conversion ratio, FCR) were calculated at the end of the feeding trial. Several hemato-biochemical parameters, such as hemoglobin (Hb), red blood cell (RBC), white blood cell (WBC) and glucose level, and frequency of micronucleus (MN) formation in erythrocytes, were analyzed. The growth parameters (WG, %WG, and SGR) and feed utilization (FE and PER) increased significantly in the fish fed with 2 and 4 mg kg-1 Cr supplemented diets. On the other hand, the growth parameters suppressed in the fish fed with 8 mg kg-1 Cr-based diet. The polynomial regression analysis based on WG showed that 2.82 mg kg-1 Cr supplementation in the diet is optimum for the tested fish species. The values of Hb (g/dL), RBC (×106/mm3) and blood glucose (mg/dL) significantly decreased in the fish fed with the highest (8 mg kg-1) Cr-based feed. Conversely, MN frequency was significantly increased in the fish fed with 8 mg kg-1 Cr-based diet. Overall, 2.82 mg Cr kg-1 can be added to the diets of striped catfish for its better growth with maximum utilization of feed.

Chromium Exposure Causes Structural Aberrations of Erythrocytes, Gills, Liver, Kidney, and Genetic Damage in Striped Catfish Pangasianodon hypophthalmus.

Heavy metal pollution due to anthropogenic activities poses a great threat to aquatic organisms. The present study was conducted to evaluate the cytotoxic and genotoxic effects of hexavalent chromium (potassium dichromate) on hemato-biochemical, histo-pathological, and genetical changes in striped catfish Pangasianodon hypophthalmus. Three sub-lethal doses (0.8, 1.6, and 3.2 mg/L) of chromium (Cr) were selected and fish were exposed in vivo contrasting with a control (0 mg/L) for 30 days. The study revealed that various hemato-biochemical parameters showed a significant decrease in hemoglobin (Hb), red blood cells (RBCs), and blood glucose content, whereas white blood cells (WBCs) significantly increased in Cr exposed fish. Frequencies of all forms of structural abnormalities of erythrocytes (erythrocytic cellular abnormalities; ECA, erythrocytic nuclear abnormalities; ENA and erythroblasts; Ebs) were significantly increased in higher two test concentrations (1.6 and 3.2 mg/L) when compared to control. Differential leucocyte count exhibited significant increase in neutrophil and decrease in lymphocytes in the highest Cr treated group. The severity of various histo-pathological changes in the gills, liver, and kidney were increased considerably with the increase of Cr concentrations. Similarly, the amount of DNA (ng/µl) decreased significantly in blood and tissues of different vital organs where the liver showed the highest decline compared to control in a concentration-dependent manner. Taken altogether, P. hypophthalmus is susceptible to Cr and can be used as a bio-indicator to assess aquatic metal pollution.

Ichthyo-diversity assessment of the Old Brahmaputra river, Bangladesh: present stance and way forward.

The study was carried out to obtain information on the present status and trend of finfish diversity of the Old Brahmaputra river, Bangladesh. Samples were collected directly from a professional fishing boat caught by different nets, traps and hooks from January 2019 to December 2019. Together with 4 exotic species, a total of 49 species under 6 families were recorded. Though a biodiversity index of 3.65854 and a dominance index of 0.030929 represent the richness of ichthyo-diversity within the river, Synbranchiformes and Tetraodontiformes were not reported throughout the study period. Linear regression analysis showed a positive correlation between water height of the river and monthly abundance of the species found. Catch composition of catfishes and snakeheads slumped while barbs showed triumph over previous findings. A majority of fish recorded were within the least concern category according to IUCN (2015) but portions also belonged to critically endangered, endangered, and vulnerable categories as well. Therefore, conservation measures must be infixed in the Old Brahmaputra river to hold the fish diversity in a sustainable state.

Hypoxia reduced upper thermal limits causing cellular and nuclear abnormalities of erythrocytes in Nile tilapia, Oreochromis niloticus.

Global warming is a threat across the world that leads to estimates of the upper thermal limits of ectothermic species. Increased water temperature up-regulates oxygen consumption and metabolic rates, and alters the physiological processes. In this study, we identified the critical thermal maxima (CTmax) and physiological responses under normoxia and hypoxia in Nile tilapia, Oreochromis niloticus. CTmax was 41.25 °C under hypoxia and 44.50 °C under normoxia. Compared to normoxia, lower values of hemoglobin (Hb) and red blood cells (RBCs) were observed at the CTmax under hypoxia. In contrast, higher values of white blood cells (WBCs) and blood glucose (Glu) levels were observed at the CTmax under hypoxia. Consequently, higher frequencies of micronucleus, cellular and nuclear abnormalities of erythrocytes were observed at the CTmax under hypoxia. These results suggest that high temperature tolerance and subsequent physiology are significantly affected by the oxygen supply in Nile tilapia. As climate vulnerability is intensifying day by day, this data will be helpful in successful management practice for the aquatic environment having low oxygen content.

Acute effects of chromium on hemato-biochemical parameters and morphology of erythrocytes in striped catfish Pangasianodon hypophthalmus.

Chromium is considered the most detrimental pollutant to the aquatic organisms. The present experiment was conducted to determine the acute toxicity of chromium in view of its effects on hemato-biochemical parameters and the structure of erythrocytes in striped catfish, Pangasianodon hypophthalmus. Fish were exposed to seven different concentrations (0, 10, 20, 30, 40, 50 and 60 mg/L) of chromium, each with three replications for 96 h. After 96 h of exposure, the survived fish were sacrificed to measure hemato-biochemical parameters (hemoglobin, Hb; red blood cell, RBC; white blood cell, WBC; packed cell volume, PCV; mean corpuscular volume, MCV; the mean corpuscular hemoglobin, MCH and blood glucose). In addition, erythrocytic cellular abnormalities (ECA) and erythrocytic nuclear abnormalities (ENA) of peripheral erythrocytes were assayed. No mortality was observed up to 10 mg/L, but 90% and 100% mortality was observed at 50 mg/L and 60 mg/L, respectively after a 96 h exposure period. The 96 h LC50 value through probit analysis was 32.47 mg/L. Hb (%), RBC (×106/mm3) and PCV (%) significantly decreased at 20, 30 and 40 mg/L of chromium, whereas WBC (×103/mm3), MCV (µm3) and MCH (pg) showed the opposite scenario. Blood glucose (mg/dL) levels significantly increased at 10, 20, 30 and 40 mg/L of chromium compared to 0 mg/L. Frequencies of ECA and ENA significantly increased with increasing chromium concentrations. This study indicates that chromium is highly toxic to striped catfish.