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According to the importance of vitamin B6 (pyridoxine) as a water-soluble vitamin on the physiological conditions of aquatic animals, the present study aimed to investigate effects of different concentrations of this vitamin in recycle system culture water on the Nile tilapia (Oreochromis niloticus). Treatments including 0 (control), 10, 20, 30, and 40 mg L−1 vitamin B6 were adjusted in triplicate recirculating systems. Each of the experimental tanks (100 L) was stocked 15 fingerling Nile tilapia during 60-day experimental period. According to the findings, weight gain in treatments of 30 and 40 mg L−1 pyridoxine was significantly higher than the other treatments while blood cortisol hormone in the treatment of 40 mg L−1 was significantly highest among the treatments. In addition, mid-intestine trypsin activity in the treatment of 40 mg L−1 was significantly higher than the other treatments. The histological analysis of the intestine showed that the number of mucus-secreting cells significantly decreased in treatments of 30 and 40 mg L−1. Our findings here suggest that pyridoxine can possibly be absorbed by the Nile tilapia’s body through culture water and it seems 20–30 mg L−1 pyridoxine in the culture water is the optimal concentration for the Nile tilapia juveniles in recycle system culture.

Larvae of Japanese smelt Hypomesus nipponensis have unique salinity adaptability and a small gape size; consequently, no system has been developed to feed them for stable high growth and survival. Therefore, suitable conditions for larval growth of Japanese smelt remain to be studied. In an earlier study, we developed a Japanese smelt rearing method using a closed recirculating system. Using that system for this study, we examined recirculation rate effects on Japanese smelt larval growth because the recirculation rate can affect larval feeding opportunities through regulation of the rotifer retention time in the rearing tanks. Using 0.2–0.3% salinity and water temperatures of less than 20 °C, we fed Japanese smelt larvae with SS-type rotifer and commercial feed. Results indicated that larval growth with a recirculation rate of less than 648% per day (LR) is superior to that achieved at a rate of over 2160% per day (HR). Moreover, rotifer density under the LR condition declines more slowly than under the HR condition. These results demonstrated that the recirculation rate affects their growth, perhaps by affecting the opportunities for larvae to ingest the rotifers. Furthermore, SS-type rotifers are available for feeding teleosts in a wide range of water temperatures and salinities.

This study was conducted at fish laboratory affiliated to the department of animal production/college of agriculture/University Of Anbar. The experiment lasted eight weeks in Aquatic Recirculating System ARS from 5th Sep 2022 to 31 Oct 2022, to examine the appropriate nutrient ratios of commercial diet For Common carp ( Cyprinus carpio L.). One hundred twenty-six fingerlings fish with 35.44± 0.44 gm. Weight randomly divided in to six treatment by three replicates, seven fish for each replicate. It housed in aquaria, with a capacity of 50 liters, its dimensions are 30 × 30 × 60 cm for each one. All fish had fed on the same diets, they were fed as follows (T1) is unlimited, open until saturation, and the other treatments T2, T3, T4, T5 and T6 were fed by 3%, 4%, 5%, 6% and 7%, respectively from their biomass weight ratio on two meals a day. The rustle showed that T4, T5 and T6 had significant increase (P≤0.05) in final weight (FW), weight gain (WG), daily weight gain (DWG), relative growth rate (RGR), specific growth rate (SGR) as compared with others. This study it could concluded, feeding fish 4% or 5% from biomass weight ratio improving growth performance and decrease wasted fodder.

As climate change reshapes agriculture and food systems across the globe, aquaculture in sub‐Saharan Africa (SSA) is at a turning point. Sustainable climate‐smart aquaculture (SCSAq) aims to make fish farming more productive, resilient to climate change, and environmentally friendly while also improving livelihoods and nutrition. This review collates and consolidates empirical findings on how SCSAq is being adopted across the region and what factors are driving or hindering its scalability. Drawing from recent studies (2015 to 2025), this paper identified key practices being used, such as recirculating systems, organic inputs, local feed production, and water‐saving techniques. The paper also synthesizes existing findings on factors influencing uptake such as education, access to finance, institutional support, and environmental conditions. Major barriers such as high start‐up costs, poor infrastructure, and limited knowledge were also identified. Finally, the wide impacts of SCSAq is discussed, showing how it can improve food security, incomes, and ecosystem health if effectively scaled up. This review highlights the need for inclusive policies, farmer‐led innovation, and cross‐sector collaboration to bridge the gap between science, policy, and practice. With the right support, SCSAq can play a significant part in building a more sustainable and climate‐resilient pathway for aquaculture in SSA.

The principal function of an open recirculating system (ORS) is to remove heat from power plant equipment. In particular, the presence of scale on the internal surfaces of ORS heat exchange equipment can reduce heat transfer efficiency, which leads to increased energy consumption and operating costs. The purpose of this article is to investigate the process of calcium carbonate (CaCO 3 ) precipitation formation in terms of the components of the carbonate system and parameters affecting the shift of carbonate equilibrium in an ORS. An appraisal model was used to represent the processes occurring during the operation of an ORS. In this study, it is demonstrated that water heating in ORS condensers leads to the excretion of carbon dioxide (CO 2 ) from the water, while cooling in the cooling towers results in CO 2 uptake by the water. These processes significantly influence the state of carbonate equilibrium within the ORS. The study used the results of chemical control of the make-up and cooling water at the ORS Rivne Nuclear Power Plant (RNPP) for 2022. Furthermore, the dependencies of changes in the components of the carbonate system on the pH levels of the make-up (pH 7.51–9.52) and cooling (pH 8.21–9.53) water were revealed, and changes in the cycles of concentration (CоC), total hardness (TH), total dissolved solids (TSD), and total alkalinity (TA) were estimated. Taking into account the obtained correlation dependencies, in general, it was found that the lower the CoC levels, the lower the TA reduction value, and it is possible to increase or decrease the cooling water pH levels, which is determined by the initial state of carbonate equilibrium of make-up water. These findings enable the prediction and control of CaCO 3 scale formation through continuous monitoring of water chemistry, making the process more efficient, reliable, and sustainable. The results emphasize the importance of data-driven modeling for optimizing water treatment and reducing operational costs in power plants by reducing CaCO 3 scale formation.

Aquaculture is globally the fastest growing sector of agriculture that needs to be sustainable and must also meet bioeconomic demands. In principle, aquaponics, the combination of aquaculture and horticulture within a single recirculating aquaponic system (SRAPS), provides a sustainable approach; however, it has lower productivity of both fish and plants in comparison to separate recirculating systems. The aim of our new concept for aquaponics is to improve sustainability and productivity concomitant with lowering environmental emissions. The aquaponic system for (nearly) emission free tomato and fish production in greenhouses (ASTAF-PRO) is a new combination of systemic parts, consisting of 2 independent recirculating units: an aquaculture system (RAS) for fish and a hydroponic unit for plants. Both systems are connected by a 1-way valve to deliver fish water containing nutrients into the hydroponic reservoir, where the fish water can be optimized as fertilizer in order to meet specific demands of the plant species. Thus, our double recirculation aquaponic system (DRAPS) can provide optimum conditions for both parts to increase productivity and to prevent any adverse interactions between plant and fish units. Water use is minimized by condensing the plant evapo-transpired water via air conditioning and returning it into the RAS. Testing of the ASTAF-PRO prototype successfully demonstrated the principle using a combination of tilapia and tomato production. Tilapia productivity was similar to single RAS, while tomato production at least indicated the potential for similar efficiency to conventional hydroponics. Thus, ASTAF-PRO improves sustainability and productivity while lowering environmental emissions, and might promote future application of aquaponics for food security.

The green alga Ulva ohnoi M. Hiraoka & S. Shimada is an effective biofiltration agent of fish effluents in Integrated Multi-Trophic Aquaculture Recirculation Systems (IMTA-RAS), due to its high growth rate and high nutrient (N and P) removal in temperate conditions. Moreover, Ulva species provide an important niche for biofilm-forming bacteria, including strains of Phaeobacter that possess antagonistic activity against pathogenic Vibrio species, and have been shown to reduce the mortality of fish in aquaculture settings. This research aimed to examine the potential of using U. ohnoi colonised with Phaeobacter sp. 4UAC3, previously isolated from natural populations of Ulva australis, as a strategy to prevent vibriosis in IMTA-RAS. The results showed that Phaeobacter sp. 4UAC3 was able to colonise and be maintained on U. ohnoi during a re-inoculation scale-up process from multi-well plates (10 mL) to flasks (4 L) and finally to tanks (40 L). Phaeobacter sp. 4UAC3 rapidly colonised the surface of the Ulva but it did not significantly modify the rest of the bacterial communities present in U. ohnoi surface in terms of diversity and composition. Infection assays using fish larvae (Scophthalmus maximus) with V. anguillarum in a model IMTA-RAS showed that Phaeobacter–colonized U. ohnoi promoted the reduction of mortality in the infected larvae, however this trend was not statistically supported. These results suggested that U. ohnoi can be experimentally colonised with Phaeobacter sp. 4UAC3 and has potential to be used in IMTA-RAS as an alternative to traditional disease control methods.

Mealworm (MW) from the red wriggler, Eisenia fetida, has been used as a dietary substitute or complement in aquaculture diets. However, the substrate in which it is cultivated varies its proximate composition. This study aimed to evaluate the inclusion of MW produced in two substrates-vegetal culture (VC) and animal culture (AC)-in mixed diets for juvenile Penaeus vannamei. A 2×3 factorial experimental design was used, consisting of two substrates (VC and AC) and three inclusion levels (5, 10, and 20%), yielding six diets, each with three replicates. Shrimp (2.29 ± 0.13 g) were cultured for 75 days in a recirculating system and were fed twice daily. Growth performance, survival, and digestive enzyme activity were evaluated. Shrimp fed with 10% VC showed a higher final weight (8.07 ± 0.39 g) and weight gain (5.66 ± 0.45 g) (P < 0.05) at the end of the experiment. The final weight, weight gain, and specific growth rate were higher in organisms fed with VC, regardless of the inclusion level. Survival was similar (˃90%) across all treatments (P ˃ 0.05). Except for lysine, the levels of essential and nonessential amino acids increased with the MW substitution level produced using both substrates. Both 10% VC and 10% AC groups showed the highest digestive protease activity (39.83 ± 3.0 and 50.87 ± 4.4 U mg protein-1 in VC and AC, respectively). In contrast, the highest chymotrypsin activity was observed in the 5% AC group (6.08 ± 0.43 U mg chymotrypsin-1). The results indicate that incorporating MW from E. fetida, produced on either substrate, into a mixed diet alters shrimp growth and enzymatic activity without affecting survival. However, future studies evaluating MW as an ingredient in formulated shrimp feeds should proceed with caution, particularly regarding the characteristics of the worm-culture substrate.

Clown loach (Chromobotia macracanthus (Bleeker,1852)), an endemic species to Indonesia, is one of the main freshwater ornamental fish in demand in the international market. The high demand for wild-caught and cultured fries supports supply sustainability. However, the difference in performance between naturally sourced and cultured fries is not fully understood. This study aims to analyze and compare the performance of Clown loach from both sources, including growth rate, survival, and color quality, after 60 days of rearing. In this study, Clown loach fries were raised using a recirculating system. There were two treatments: wild-caught and cultured juveniles, repeated three times each. Juveniles measuring 1.5-2 cm were stocked at three fish/L of water. The results showed that Clown loach from the wild exhibited better growth potential than those from culture. The average growth rate of wild-caught Clown loach reached 3.731+0.087%, significantly higher than that of cultured fish, which only reached 2.020+0.082%. The survival rate between the two groups did not differ significantly, with wild-caught Clown loach recording a survival rate of 98%, while farmed fish reached 91%. The study revealed that wild-caught Clown loach demonstrated superior growth rate, survival, and color quality than farmed fish.

A study was conducted to collect information on the welfare status of salmonids reared in freshwater in southern Chile and to identify the most suitable operational welfare indicators (OWIs) for application in hatcheries. The study was carried out with the voluntary participation of 54 hatcheries that represent 36% of the total number of freshwater hatcheries operating in Chile, which were classified according to the production stage and comprised 12 hatcheries with recirculation system (RAS); 32 hatcheries with flow-through system (FTS); 7 hatcheries with water reuse system (REU) and 3 hatcheries with mixed system (FTS+RAS). Thirty OWIs were selected as the most suitable from the consulted literature and from a questionnaire administered to the fish farmers participating in the study. Three aspects were considered: animal welfare, feasibility, and economic cost, which were grouped into indirect (15) and direct OWIs (15). The OWIs were validated in 16 hatcheries where incubation, fingerling, and smoltification steps were covered. The results enabled the identification of critical conditions for the welfare of farmed fish, both in flow-through hatcheries and recirculation hatcheries, for the three salmonid species reared in Chile (Atlantic salmon Salmo salar, coho salmon Oncorhynchus kisutch, and rainbow trout Oncorhynchus mykiss). Water quality was considered the most critical issue for smolt production in freshwater, followed by precocious maturation in Atlantic salmon males, observed primarily in RAS hatcheries, and mortality classified as non-infectious. The latter included the culling of fish that are considered not suitable for commercial production.