Sustainable Aquaculture Systems Research Articles

Effects of Ferulic Acid on Respiratory Metabolism, Oxidative Lesions, and Apoptotic Parameters in Gills and Red Blood Cells of Carp (Cyprinus carpio Var. Jian) Response to Copper.

In sustainable aquaculture systems, copper sulfate (CuSO4) is widely applied as a disinfectant to control parasitic infections and algal growth. However, aquatic organisms may suffer from exposure to excessive concentrations of Cu. Elevated Cu concentrations could activate damage to the respiratory functions of aquatic animals. Thus, this study explored the effects exerted by ferulic acid (FA) on respiratory metabolism, oxidation-related lesions, and the apoptosis parameters of the gills and red blood cells in copper sulfate pentahydrate (CuSO4·5H2O)-treated carp (Cyprinus carpio var. Jian). When the 30-day feeding experiment was completed, the carp were exposed to 12.5 μM of Cu for 4 days. The results indicated that the Cu decreased the oxygen consumption and ammonia excretion rates in the carp, reduced the metabolic- and antioxidant-related enzyme activities and glutathione levels in the carp, and enhanced the caspase activities and reactive oxygen species and malondialdehyde levels in the gills of the carp. Moreover, in addition to the changes in the above parameters, the Cu decreased the cell numbers and hemoglobin concentrations and increased the phosphatidylserine exposure and cytochrome c levels in the red blood cells of the carp. These results demonstrate that Cu is capable of decreasing respiratory metabolism and increasing oxidation-related lesions and apoptosis inside the gills and red blood cells of the fish. However, dietary FA quenched the Cu-induced apoptosis and oxidative lesions by reversing the same biomarker indicators, thereby suppressing the Cu-induced decrease in respiratory metabolism. Thus, FA can be used as a suppressor of Cu stress in fish.

Biofloc System with Different Carbon Sources Improved Growth, Haematology, Nonspecific Immunity, and Resistivity against the Aeromonas hydrophila in Common Carp, Cyprinus carpio

Biofloc technology (BFT) is one of the most sustainable aquaculture system, which is based on the principle of nutrient recycling and addition of carbon to enable heterotrophic microorganisms to the system. To evaluate the performance of the biofloc culture system for Cyprinus carpio fingerlings, a 60-day growth trial was conducted. The fingerlings (n = 600) of average body weight (4.92 g ± 0.14) were stocked in 12 circular fiberglass tanks (300 L, volume 10.59 cft) to form three biofloc treatments (T1, T2, and T3) along with one control group. The carbon sources for treatments were sugarcane molasses, tapioca, and wheat. The C/N ratio of 15 was maintained for all treatments. After 60 days of rearing, the fish were challenged with Aeromonas hydrophila, and the relative percentage survival (RPS) was observed over 14 days. A haematological, nonspecific immune, and stress parameters were analyzed using blood and serum samples collected at intervals of 20, 40, and 60 days. According to the results, the carbon sources affected the water quality parameters but were still adequate for fish welfare. An increased biofloc volume was observed with tapioca. Growth performance and better feed conversion ratio were recorded in biofloc with the tapioca group. The hematological parameters, including haemoglobin (Hb), hematocrit (HCT), white blood cells and lymphocytes were significantly (P <0.05) higher in biofloc-based tapioca group than in other treatments and control. Further, the serum protein, globulin, albumin, total immunoglobulin, and respiratory burst activity were also found significantly (P <0.05) higher in biofloc with tapioca as carbon source. However, the lysozyme activity was higher in biofloc with the wheat group. The RPS in tapioca was significantly higher, followed by biofloc with wheat. In conclusion, the tapioca-based biofloc can improve C. carpio growth, haematology, and nonspecific immune response under zero water exchange.

Algae and indigenous bacteria consortium in treatment of shrimp wastewater: A study for resource recovery in sustainable aquaculture system

Shrimp production facilities produce large quantities of wastewater, which consists of organic and inorganic pollutants. High concentrations of these pollutants in shrimp wastewater cause serious environmental problems and, therefore, a method of treating this wastewater is an important research topic. This study investigated the impact of algae and indigenous bacteria on treating shrimp wastewater. A total of four different microalgae cultures, including Chlorococcum minutus, Porphyridum cruentum, Chlorella vulgaris and Chlorella reinhardtii along with two cyanobacterial cultures, Microcystis aeruginosa and Fishcherella muscicola were used with indigenous bacterial cultures to treat shrimp wastewater. The highest soluble chemical oxygen demand (sCOD) removal rate (95%) was observed in the samples that were incubated using F. muscicola. Total dissolved nitrogen was degraded >90% in the C. vulgaris, M. aeruginosa, and C. reinhardtii seeded samples. Dissolved organic nitrogen removal was significantly higher for C. vulgaris (93%) as compared to other treatments. Similarly, phosphate degradation was very successful for all the algae-bacteria consortium (>99%). Moreover, the degradation kinetics were calculated, and the lowest half-life (t1/2) for sCOD (5 days) was recorded for the samples seeded with M. aeruginosa. Similarly, treatment with F. muscicola and C. reinhardtii showed the lowest t1/2 of NH3–N (2.9 days) and phosphate (2.7 days) values. Overall, the results from this study suggest that the symbiotic relationship between indigenous bacteria and algae significantly enhanced the process of shrimp wastewater treatment within 21 days of incubation. The outcome of this study supports resource recovery in the aquaculture sector and could be beneficial to treat a large-scale shrimp facility's wastewater worldwide.

Ⅱ–4.　Sustainable aquaculture systems adapted to the fisheries industry in Japan

Ⅱ–4.　Sustainable aquaculture systems adapted to the fisheries industry in Japan

The Effects of Different Carbon Sources on Water Quality, Growth Performance, Hematology, Immune, and Antioxidant Status in Cultured Nile Tilapia with Biofloc Technology

The biofloc technology system (BFT) is considered to be one of the sustainable aquaculture systems, which is based on the principle of nutrient recycling with the addition of a carbon source to give dominance to heterotrophic microorganisms. The objective of this study was to evaluate the effect of sugar cane molasses and tapioca flour as carbon sources on the water quality, growth, hematology, immune status, and non-specific antioxidant status of Oreochromis juveniles. Methodologically, the experiment was carried out for 10 weeks on 225 juvenile Nile tilapia with initial body weights of 47.0 ± 1.3 g that were randomly distributed in 09 tanks (1000 L) with a stocking density of 25 tilapias per tank; the treatments were: BFT + SM (S molasses), BFT + TF tapioca flour (TF), and a control with no carbon source added. The control group was fed 100% feed, while the BFT experimental groups were fed microbial flocs along with 75% feed. The results revealed that the water quality parameters were affected by the carbon sources, but were adequate for normal fish welfare, and the biofloc volume was higher (28.94) with the TF carbon source. The growth performance, such as weight gain (98.61), survival (99.01), and improved feed conversion ratio (FCR) (1.69), was recorded in BFT + TF. Significant improvements in WBCs, HCT, HB, lymphocytes, plasma proteins, albumin, and non-specific immune factors (lysozyme activity, immunoglobulins levels, and ACH50) were observed in biofloc-reared fish with tapioca flour as the carbon source compared to the control and sugarcane molasses groups. Moreover, significant increases in catalase (CAT) and superoxide dismutase (SOD) were found in the biofloc-reared fish with different carbon sources. In conclusion, the use of BFT + TF was found to affect improving the water quality, growth, hematology, immunity, and antioxidant status of juvenile Tilapia.

Biofloc technology as part of a sustainable aquaculture system: A review on the status and innovations for its expansion

AbstractIncreased food demand, reflecting a rising global human population, attaining 8 billion in 2022, has furthered the intensification of farmed aquatic animal production. Intensification practices can be resource demanding for micro and macronutrients, dedicated feeds, fossil fuels, chemotherapeutics, and water. Water replaces evaporative losses and may be used to dilute nutrient‐rich wastewater. As an alternative to wastewater discharge, biofloc technology (BFT) uses microbes to manage nutrient levels in production systems. A microbial community grown at high densities can assimilate waste metabolites for growth. This is promoted by increasing the carbon–nitrogen (C:N) ratio using a combination of aquafeed fed to the fish and an additional carbohydrate source, for example, starch, molasses, or bran. The microbial biomass offers a continuous and additional food source to the farmed animal, thus reducing the need for finished aquafeeds and lowering the feed conversion ratio. Although the approach relies on multiple interacting species, BFT can be deployed in relatively low technology settings. This review considers the basis of BFT and identifies areas for innovation and expansion. For example, control of light quantity and quality can influence the biofloc and hence the growth of cultured species. Research on biofloc aquaculture is dominated by studies using tilapia and shrimp, but the technology could be applied to other species, particularly species that are tolerant of biofloc conditions and not highly carnivorous. Biofloc may be a useful biosecurity tool for all or part of the life cycle, and meals made from dried biofloc may enhance the production of cultured species. The key benefits of BFT can potentially be seen in reduced water consumption, lower feed requirements, and improved fish health. This review differs from current review papers in proposing the use of a life cycle assessment in conjunction with BFT, which may be a useful tool for describing and communicating the relative benefits of biofloc systems and their wider environmental impact. This study will serve as a useful knowledge base of BFT information for students, researchers, and stakeholders alike, offering a central source of the main aspects around the culturing of biofloc, key parameters, common species used, areas of potential improvement, and a discussion on where the future of BFT may lie.

Challenges and Barriers for Aquaculture Sector: Review Article on Freshwater Aquaculture

The EU aquaculture sector, like other sectors of the EU economy, must participate in the ‘green transition’ set out in the European Green Deal. The sector has a particular role to play in contributing to the transition towards sustainable food systems and the development of the bioeconomy and circular economy. Aquatic organisms and fish cultivated in aquacultures are important sources of food and feed, the importance of developing which has been highlighted in several EU policy planning documents. Due to high nutritive value, fish and aquatic organisms are a valuable food source. Despite the rapid growth of aquaculture in Europe and other parts of the world, the promotion of sustainable or organic aquaculture is crucial for the provision of high-quality, locally accessible food. Aquacultures produce relatively low greenhouse gas emissions compared to sources of protein grown on land. However, there is still room for growth, therefore, to further reduce greenhouse gas emissions from aquacultures and foster more sustainable practices and greater resource and energy efficiency are required. This review article includes an analysis of policy planning documents adopted in Latvia and the EU, outlining opportunities and risks for creating a sustainable aquaculture industry. The purpose of this review article is to identify the most significant problems and obstacles to achieving a sustainable aquaculture system at both the local and European levels. In addition, the review investigates and contrasts recent advancements in aquaculture technological processes and socioeconomic impact factors. Whether aquaculture’s path to sustainability is jeopardized by inefficient consumption of resources and wastes (feed, energy, emissions) at the beginning or end of the organisms’ life cycle.

Improvement of muscle quality in tilapia (Oreochromis niloticus) with dietary faba bean (Vicia faba L.).

Tilapia (Oreochromis niloticus) is a freshwater fish which is farmed worldwide. Improving the muscle quality of fish has become a major goal while maintaining a sustainable aquaculture system. This research attempts to assess the effect of 0% (FB0), 40%(FB40), 50%(FB50), 60%(FB60) and 70% (FB70) faba bean on the texture parameter, histological analysis, proximate, amino acids, and fatty acids composition in tilapia fed 90 days. The results showed that hardness, chewiness, and shear force of tilapia muscle fed FB60, and FB70 were considerably more in comparison to fish fed FB0 at 90 days (p < 0.05). Tilapia fed faba beans had higher muscle fiber density, wider spaces between muscle fibers and smaller fiber diameter, with the greatest difference in tilapia fed FB60. The total protein content in tilapia fed FB40 was considerably more in comparison to in fish fed FB70 (p < 0.05), where the total protein content in muscle first increased and then reduced with increasing dietary faba bean level. The muscle ∑TAA, ∑EAA, valine, tyrosine, cysteine, aspartic acid, methionine, isoleucine, glutamic acid, leucine, arginine, and serine, contents in tilapia fed FB60 were much more in contrast to in fish fed FB0 (p < 0.05), which initially increased and then reduced with increasing dietary faba bean level. The muscle ∑PUFA content in tilapia fed dietary faba beans was greater compared with fish fed FB0, whereas the ∑SFA contents in tilapia fed FB50 and FB60 were lower in contrast to in fish fed FB0. In summary, dietary faba beans can improve muscle texture, muscle fibers, amino acids content and fatty acids content in tilapia. The research's results make a contribution to the improved knowledge of the association among muscle quality in tilapia and dietary faba beans.

Metagenomic insights into feasibility of agricultural wastes on optimizing water quality and natural bait by regulating microbial loop

Effective screening feed substitutes for improving water quality in aquaculture systems has become a trending research topic now. In this study, three typical organic agricultural wastes, including sugar cane bagasse (SC), coconut shell powder (CS), and corn cob powder (CC), were selected to evaluate their potential roles on the optimization of water quality and natural bait compared to aquafeeds. Fish feed resulted in the highest growth rate of fish but the worst water quality. Organic detritus addition markedly improved the water quality, especially soluble reactive phosphorus (SRP, decrease of 56–61%) and ammonium (decrease of 16% in SC, 47% in CC). Specially, SC induced core microbes to mediate nutrients transformation and recycling (N2-fixation, ammonification, nitrification, dissimilatory nitrate reduction to ammonia and organic nutrients decomposition), which facilitated the primary productivity based on their positive relationships. This further reduced the available nutrients (especially SRP) in the water and built a mutually beneficial microbial loop. In addition, SC addition increased the abundance of genes involved in amino acids biosynthesis pathways, photosynthesis, and carbon fixation. These results led to energy transfer to higher trophic levels. The addition of CC had a better effect than SC in terms of lower nitrogen levels and a higher fish growth rate (19% in CC, 5% in SC). However, low temperatures and carbon accumulation jointly drive the anaerobic decomposition, resulting in unhealthy microbial loops and low fish growth rates. In contrast to the direct consumption of fish feed, organic detritus can induce more natural bait to provide food for fish by regulating the microbial loop, as showed by the microbial community composition in the water and fish gut. To comprehensively assess water quality, natural bait, and fish growth and quality, certain organic detritus should be considered as an auxiliary material to partially replace feed for healthy and sustainable aquaculture systems.

Towards sustainable aquaculture systems: Biological and environmental impact of replacing fishmeal with Arthrospira platensis(Nordstedt) (spirulina)

Sustainable fish food production is crucial for aquaculture. Microalgae, such as spirulina (Arthrospira platensis), can supplement diet antioxidants or replace expensive fishmeal with high-quality proteins. In this study, we tested fish growth and wellbeing by feeding fish on a diet in which 5% of fishmeal was replaced by spirulina (SP5 diet). The low level of spirulina in the diet was intended as supplementation and was effective in ameliorating the redox state of a model fish species (juvenile Koi Carp, Cyprinus carpio L.) in a preliminary lab protocol in a six-week trial. When compared with both the control diet (no Spirulina) and a diet containing 30% spirulina replacing fishmeal (SP30 diet), SP5 was able to reduce the muscle levels of reactive oxygen species (ROS), oxidative damage, and susceptibility to oxidative stress, while increasing glutathione reductase and peroxidase activity. However, high production costs and impacts still limit the use of spirulina in fish diet. Recent studies focused on growing spirulina on urban or agro-industrial wastewater, with appropriate profiles for the alga growth. Therefore, in a circular economy context, a possibility still to be tested and exploited is feeding farmed fish with spirulina produced on output wastewater recirculated back from the same farming plant. Life Cycle Assessment (LCA) was applied to estimate the sustainability of such “circular” fish farming. The LCA ReCiPe Midpoint (H) impact assessment method was used. Firstly, the LCA environmental impacts associated with the production of spirulina grown on aquaculture wastewater as well as on the standard culture medium (Zarrouk medium) were assessed and compared by means of a “gate to gate” analysis. Then, the LCA impacts of an SP5 diet for fish, in which spirulina grown on aquaculture wastewater was used to replace 5% fishmeal (SP5ww), were compared to the diet containing spirulina grown on a standard medium (SP5st) and that one without spirulina (control diet). Results indicated that SP5ww was significantly less impacting, by avoiding the treatment and disposal of wastewater and the need for the highly impacting standard culture medium. In conclusion, the proposed approach for using spirulina in aquaculture represents a valid solution for aquaculture circular economy scenario while at the same time improving fish welfare.

The digestive tract sections of the sea cucumber Isostichopus badionotus reveal differences in composition, diversity, and functionality of the gut microbiota.

For the first time, this study analyses the composition and diversity of the gut microbiota of Isostichopus badionotus in captivity, using high-throughput 16S rRNA sequencing, and predicts the metagenomic functions of the microbiota. The results revealed a different composition of the gut microbiota for the foregut (FG) and midgut (MG) compared to the hindgut (HG), with a predominance of Proteobacteria, followed by Actinobacteria, Bacteroidetes, and Firmicutes. The FG and MG demonstrated a greater bacterial diversity compared to the HG. In addition, a complex network of interactions was observed at the genus level and identified some strains with probiotic and bioremediation potentials, such as Acinetobacter, Ruegeria, Streptococcus, Lactobacillus, Pseudomonas, Enterobacter, Aeromonas, Rhodopseudomonas, Agarivorans, Bacillus, Enterococcus, Micrococcus, Bifidobacterium, and Shewanella. Predicting metabolic pathways revealed that the bacterial composition in each section of the intestine participates in different physiological processes such as metabolism, genetic and environmental information processing, organismal systems, and cellular processes. Understanding and manipulating microbe--host-environment interactions and their associated functional capacity could substantially contribute to achieving more sustainable aquaculture systems for I. badionotus.

Transcriptomic Analysis of Fish Hosts Responses to Nervous Necrosis Virus.

Nervous necrosis virus (NNV) has been responsible for mass mortalities in the aquaculture industry worldwide, with great economic and environmental impact. The present review aims to summarize the current knowledge of gene expression responses to nervous necrosis virus infection in different fish species based on transcriptomic analysis data. Four electronic databases, including PubMed, Web of Science, and SCOPUS were searched, and more than 500 publications on the subject were identified. Following the application of the appropriate testing, a total of 24 articles proved eligible for this review. NNV infection of different host species, in different developmental stages and tissues, presented in the eligible publications, are described in detail, revealing and highlighting genes and pathways that are most affected by the viral infection. Those transcriptome studies of NNV infected fish are oriented in elucidating the roles of genes/biomarkers for functions of special interest, depending on each study’s specific emphasis. This review presents a first attempt to provide an overview of universal host reaction mechanisms to viral infections, which will provide us with new perspectives to overcome NNV infection to build healthier and sustainable aquaculture systems.

Polyculture of tilapia (Oreochromis niloticus) and lemeduk (Barbonymus schwanenfeldii) in floating net cages as a strategy for utilizing natural food

Polyculture is a sustainable aquaculture system because it can reduce environmental pollution and increase feeding efficiency. The purpose of this study was to analyze the performance of growth, biomass and food competition for tilapia as the main commodity and lemeduk fish as a secondary commodity with a polyculture system in floating net cages. The research method used a Completely Randomized Design (CRD) consisting of 5 treatments and 3 replications, namely: treatment A (60 tilapia fish), Treatment B (40 tilapia fish + 20 lemeduk fish), Treatment C (30 tilapia fish + 30 lemeduk fish), Treatment D (20 tilapia fish + 40 lemeduk fish), and Treatment E (60 lemeduk fish). The research container uses floating net cages with a size of 0.5 × 0.5 × 1m. Parameters observed were absolute length growth, absolute weight growth, specific growth rate, biomass production, competition index, and water quality. The results showed that the polyculture system of tilapia and lemeduk at different stocking densities had a significant effect on absolute length growth, specific growth rate, biomass production, and had low competition between tilapia and lemeduk. The best treatment was found in treatment B (N 40+ L 20) and treatment C (N 30+ L 30) with absolute length growth value 3.20 cm±0.17, specific growth rate 3.83%±0.36, biomass of tilapia 94.36 g/0.5m2±16.45 and total biomass 100.69 g/0.5m2±5.49. Hence, the polyculture system is better than the monoculture system and the absence of competition between tilapia and lemeduk in using food.

Environmental sustainability of future aquaculture production: Analysis of Singaporean and Norwegian policies

To address global food demand and sustainability challenges, aquaculture has appeared as an essential element in food systems, and an increasing number of national aquaculture policies have emerged over the past decades. However, several of these policies have failed because of an often-argued inability to anticipate their far-reaching implications on environmental and socio-economic variables. To tackle this gap, we propose a step-wise framework to assess the national environmental impacts from aquaculture industries with a prospective and systemic approach. Starting from identifying policy-based national targets, the methodology relies on economic equilibrium modeling to develop realistic future-oriented scenarios of the aquaculture sector, and couples them with life cycle assessment principles. To evidence its operability, we apply the framework to two distinct case countries: Norway and Singapore. Beyond our key findings from the analyses of the policies in both countries, we observed that feed production and usage are important drivers of impacts, hence calling for new and more environmentally-friendly feed options. Our results additionally show that the development of aquaculture following existing governmental policies may not directly reduce greenhouse gases emissions and, hence, not support climate change mitigation objectives. These findings should however be cautioned as potential shifts of diets due to the increasing seafood availability might occur, leading to indirect environmental benefits. We therefore advocate the further expansion of our framework to cover the entire food system, so it can integrate such indirect effects. Meanwhile, we recommend its interim application to support policy-making and help move towards more environmentally sustainable aquaculture systems.

Experimental Study of the Environmental Effects of Summertime Cocultures of Seaweed Gracilaria lemaneiformis (Rhodophyta) and Japanese Scallop Patinopecten yessoensis in Sanggou Bay, China

The shellfish–algae mode of integrated multitrophic aquaculture (IMTA) is a sustainable aquaculture method that benefits the environment and the carbon cycle. However, most current shellfish–algae aquaculture modes are based on the expansion of kelp aquaculture. Due to the low tolerance of kelp to high temperatures, integrated shellfish–algae aquaculture areas often become shellfish monocultures in summer, which may lead to both high mortality rate of shellfish and to economic loss while causing serious environmental harm via eutrophication, decreases in dissolved oxygen (DO), and decreases in pH. In this study, we investigated the effects of different ratios of seaweed (Gracilaria lemaneiformis), which is tolerant of high temperatures, to Japanese scallop (Patinopecten yessoensis) on water quality and environmental parameters. A two-day small-scale enclosure water body experiment was conducted in Sanggou Bay (Shandong, China) in August 2019. The results demonstrated that culturing shellfish alone significantly affected pH, DO, eutrophication, and other environmental indicators, as well as the carbonate system. The negative environmental impact of the shellfish–algae aquaculture system was much smaller. However, too high a proportion of algae might consume excessive amounts of dissolved inorganic nitrogen (DIN) and nutrients, while too low a proportion of algae might not fully absorb the nutrients released by the cultured shellfish, in turn leading to an increased risk of eutrophication. The shellfish–algae aquaculture system not only improved the inorganic carbon system, but also the organic carbon system. At the end of the experiment, all the parameters of the inorganic carbon system had decreased significantly, while all the parameters of the organic carbon system had increased significantly. The results of this study illustrate the need to include macroalgae rotations in summer, and that an appropriate ratio of shellfish to algae is necessary to achieve a sustainable aquaculture system. Moreover, this research has also confirmed the importance of the future and related research in the actual production, which will provide useful information to guide governmental strategies for summer aquaculture rotations and insight into the controversy concerning whether aquaculture is a carbon source or sink.

Biofloc Systems for Sustainable Production of Economically Important Aquatic Species: A Review

The increasing global population has led to an increase in food demand; consequently, aquaculture is one of the food production sectors that has offered opportunities to alleviate hunger, malnutrition, and poverty. However, the development of a sustainable aquaculture industry has been hindered by the limited availability of natural resources as well as its negative impact on the surrounding environment. Hence, there is an urgent need to search for better aquacultural production systems that, despite their high productivity and profitability, utilize fewer resources such as water, energy, land, and capital in conjunction with a negligible impact on the environment. Biofloc technology (BFT) is one of the most exciting and promising sustainable aquaculture systems; it takes into account the intensive culture of aquatic species, zero water exchange, and improved water quality as a result of beneficial microbial biomass activity, which, at the same time, can be utilized as a nutritious aquaculture feed, thus lowering the costs of production. Furthermore, BFT permits the installation of integrated multi-trophic aquaculture (IMTA) systems in which the wastes of one organism are utilized as feed by another organism, without a detrimental effect on co-cultured species. This review, therefore, highlights the basics of BFT, factors associated with BFT for the successful production of aquatic species, the significance of this food production system for the sustainable production of economically important aquatic species, its economic aspects, drawbacks, limitations, and recommended management aspects for sustainable aquaculture.

An Application of the Internet of Things on Sustainable Aquaculture System

Hydroponics is one of the human significant food sources. This paper proposed the model of the system, Feasible Fish-Farming System (SFFS), which can make the water cultivating framework more practical, employing applying the Internet of things (IoT) to lessen the need for energy for controlling the climate. Little freshwater fish species (SFFs) (length &lt;25 cm) are exceptionally plentiful in nutrient A, calcium, iron and so on and consequently can add to social wellbeing through a supplement to country networks. Under the pressing factor of broad current rural practices and aimless collecting, loads of SFFs are step by step declining, and their environments and favourable places are likewise being crumbled at a quicker rate. A superior protectionist approach could be the carp-SFFS combination which will decrease aimless mass catch fishing of SFFs and will guarantee the preservation of normal SFFs stocks in their territories giving financial advantage to partners. Various investigations have effectively showed an example of overcoming adversity of SFF polyculture through carp—SFFs joining. This creation cum preservation practice prompts manageability—a superior term in the fishery is 'social fishery'. The part that needs consideration is the taking care of nature of SFFs to comprehend inside and between species (with carps) food apportioning and living space inclination as better culture cum conservational approach. Exploration in hydroponics is a contribution to increment settled creation. In the last decade, different researchers have supported attempts that came about in advancing current creation advances that have altered homestead creation. Fish developing is having the chance to be a champion among the most remunerating ambitious activities on account of the low advancement, insignificant exertion course of action-adventure and the 3 to half-year gathering cycles. IoT advancements have altered homestead creation in the country. In this paper, we propose an idea to distinguish far off observing the fish cultivating framework by utilizing the different sensors to diminish the dangers. In this paper, we utilize different sensors like pH worth, temperature and level sensors. By utilizing these sensors, all the work is mechanized, and it will likewise be not challenging to screen the fish cultivating distantly from other areas. The SFFS coordinates the sun-based homestead and fish-ranch to lessen the additional energy input. Furthermore, the lighting of LEDs is utilized to help the photosynthesis in the evening. This way is more energy-proficient than the customary siphoning. Besides, this model shows the subjective accessibility of SFFS.

Comparison for ecological economic performance of Chinese sea perch (Lateolabrax Maculatus) under different aquaculture systems

Chinese sea perch (Lateolabrax Maculatus) is one of the main marine fish culture species in China, its green development has received increasing attention and its ecological economic study is rare. Based on field survey, this paper takes water pollution tax of China as conversion indicator for aquaculture eutrophication to simulate aquaculture waste fee for further analyzing the ecological impact of Chinese sea perch's aquaculture. For data analysis, data envelopment analysis model has been used. The comparison for Chinese sea perch's economic performance and ecological economic performance under its main aquaculture systems has been done. The results show that: 1. The simulated waste fee has no significant impact for the comparison. 2. Ranking for ecological economic performance's ecological economic, technical and scale efficiency is as follow: pond farming, offshore cage culture and cage culture. 3. Offshore cage culture is the only system presenting positive increase for ecological economic performance, which makes its aquaculture activity more sustainable than other systems. 4. The key point of green development is to maximize the ecological economic efficiency of main aquaculture systems. Thus, offshore cage culture is the most sustainable aquaculture system among China's current marine fish culture systems, and other systems need innovation for achieving the green development of China's aquaculture.

Effects of different carbon sources on water quality, biofloc quality, and growth performance of Nile tilapia (Oreochromis niloticus) fingerlings in a heterotrophic culture system

The biofloc system is one of the novel sustainable aquaculture systems, and adding carbonaceous organic matter is the basis of the system. This study aimed to evaluate the effects of different carbon sources on water quality, biofloc composition, and growth performance of Nile tilapia (Oreochromis niloticus). In this study, one control group (no carbon source addition) and four biofloc treatments with molasses (TM), starch (TS), barley flour (TB), and corn (TC) addition with three replications were considered. Altogether, 160 Nile tilapia with an average weight of 1.7 g were stocked in each of the 300-l tanks (160 l of water volume). The results of water quality indicated that the lowest levels of dissolved oxygen (5.43 mg/l) and pH (7.28) were observed in the TS treatment, which showed a significant difference (P < 0.05) compared to other treatments. There was a significant difference among various treatments in nitrogen compounds and the total density of heterotrophic bacteria. Biochemical quality of biofloc was affected by various carbon sources. The highest levels of protein (31.09%), lipid (3.89%), and ash (32.79%) were observed in TB, TC, and TM treatments, respectively. The largest biofloc size was obtained in TS treatment. The lowest survival rate and the highest level of weight gain of Nile tilapia were observed in control group. In conclusion, the present study showed that different sources of carbon in the biofloc system have different effects on water quality, biochemical composition, and biofloc size produced in cultivation tanks.

A Novel Recirculating Aquaculture System for Sustainable Aquaculture: Enabling Wastewater Reuse and Conversion of Waste-to-Immune-Stimulating Fish Feed

Recirculation aquaculture system (RAS) is a unique indoor fish farming method. Yet, the RAS system needs to address challenges such as effective wastewater/waste management, reduction of feed cost, and usage of antibiotics during farming to become a sustainable aquaculture system. Here, we report a novel RAS-polyhydroxybutyrate (PHB) system to overcome these challenges simultaneously. The RAS-PHB enables effective aquaculture wastewater (AW) treatment for reuse while producing and harvesting PHB-rich biomass as a protein-rich, immune-stimulating fish feed without the need for antibiotics. The feasibility of nitrogen recovery from AW for nonsterile cultivation of a salt-tolerant PHB-producing strain (Zobellella denitrificans ZD1) with or without supplementing agro-industrial wastes/wastewaters (e.g., glycerol, cheese whey wastewater, and aquaculture solid waste) was examined. Glycerol-grown Z. denitrificans ZD1 showed high contents of PHB (48%) and proteins (45.5%). High harvest efficiency of PHB-rich Z. denitrificans ZD1 (97%) was achieved by using small amounts of medium-molecular-weight chitosan. A simple economic analysis showed that the production costs were 0.6–0.7 $/kg of fish produced for the RAS-PHB and 1.2–1.6 $/kg for the conventional RAS, suggesting a reduction of 56% of the total cost by using a RAS-PHB. Overall, this proof-of-concept study showed that the RAS-PHB system is promising for future sustainable aquaculture practice.