Safina Musa, Christopher Mulanda Aura, Tumi Tomasson
et al.
ABSTRACT Feed costs and limited knowledge of feeding strategies are a major constraint to the sustainability of semi‐intensive Nile tilapia aquaculture systems in sub‐Saharan Africa. In semi‐intensive systems, Nile tilapia ( Oreochromis niloticus ) utilizes natural pond production and supplemental feed, but their relative contributions to growth remain unclear. A 90‐day pond experiment assessed the effects of feeding regimes on Nile tilapia trophic dynamics and growth. Fingerlings (5.6 ± 0.14 g) were stocked at 3 fish m −2 in 15 ponds and assigned to five treatments: low (1%), medium (2%) and high (4%) feeding under standard fertilization and two double‐fertilized treatments with continuous low feeding (DF/L) or delayed feeding (DF/2N/1M; no feed for 60 days, then 2% for 30 days). Diet composition was assessed using δ 1 3 C and δ 1 5 N mixing models. Growth did not differ among treatments in the first 2 months but diverged in the last month. Delayed feeding combined with fertilization (DF/2N/1M) resulted in superior growth performance, efficient feed utilization and limited physiological stress compared to continuous feeding. Stable isotope analysis showed that fish in M, DF/L and DF/2N/1M fed mainly on zooplankton with limited detectable feed assimilation based on endpoint muscle isotope signatures. H fish consumed mostly sediment organic matter, whereas L fish had a mixed diet of feed, zooplankton, zoobenthos and sediment. These findings align with earlier stomach content studies showing tilapia <80–100 g rely primarily on secondary pond production rather than feed, though isotopic lag may have masked late feed uptake. These findings demonstrate that optimized feeding strategies can enhance productivity while reducing feed inputs, thereby improving the sustainability of semi‐intensive Nile tilapia aquaculture in East Africa.
Khrystyna Kurta, José Beirão, Benjamin Thomason
et al.
ABSTRACT Gaps in knowledge exist regarding sperm quality in farmed fish and its variation with age. The literature shows differing results among populations with diverse genetic backgrounds. Data collected from captive mass‐spawning Norwegian Arctic charr were analysed to investigate sperm quality parameters and their age‐related variations. We conducted a retrospective review of 63 milt analysis records from broodfish aged 2–9 years. Sperm motility and kinetic parameters decreased significantly ( p < 0.05) with advancing age, whereas no significant changes were observed in sperm concentration. A regression model explaining approximately 30% of the variation (adjusted R 2 ≈ 0.3) suggested a significant and negative effect of age on sperm swimming velocities ( p < 0.05). Finally, the analysis of the ddRAD data did not reveal significant genetic associations. Overall, this study provides valuable insights into age‐related trends and may serve as a foundation for further investigations into the sperm quality performance of populations with varying reproductive strategies and genetic structures.
Lorenz Gygax, Lars Christian Gansel, Edna Hillmann
ABSTRACT In this viewpoint, we highlight two issues that we believe deserve more emphasize in the ongoing discussions on fish welfare. On the basis of the naturally or artificially selected proximate behavioural mechanism, an animal today may attempt to reach goals that are not necessarily equal to the functions that yielded higher fitness in the past process of evolution. These attempts lead to proximate ‘needs’ of animals. Accordingly, we can increase fish welfare by asking what goals fish are trying to reach (‘wanting’) and which results will satisfy their resulting needs (‘liking’). This can be done independently of the hard question about their subjective experiences. Because answering such questions of wanting and liking relies on highly experimental procedures, we should additionally think about approaches to assess fish welfare in practice in a way that goes beyond health aspects, too. Recently developed techniques open exciting avenues to tap into judgement biases of populations that may indicate welfare and may be applicable in large‐scale fish production systems. Being aware of these two issues hopefully helps to temper the conflict between the two current extreme poles of either negating or assuming a high level of fish sentience in the discussion of fish welfare.
Phosphorus is an essential element for plants, animals, and other living organisms. The lack of phosphorus in aquatic environments can restrict primary productivity, a concern that has increasingly attracted global attention. However, the high phosphorus concentration leads to the eutrophication of water bodies, impacting human activities, compromising water quality, and causing notable economic losses. Therefore, studies on phosphorus removal and the recovery of phosphorus resources are important. In 2023, 27.3% of China's important fishery waters in inland rivers exceeded the total phosphorus standard. The area of marine natural important fishery waters that exceeded the standard for reactive phosphate was 27.0%, and the area of seawater key aquaculture areas that exceeded the standard for reactive phosphate was 28.2%, . Aquaculture development is particularly important in the context of the 'Big Food Concept'. The China's total aquatic product output in 2023 was 71.16 million tons, an increase of 4.39% year-on-year, of which aquaculture production accounted for 81.6%. From 2022 to 2024, China's provinces and municipalities introduced the aquaculture tail water discharge standard. For example, Shandong Province has implemented DB37 4676-2023, which sets a total phosphorus primary discharge limit of 0.7 mg/L and a secondary discharge limit of 1.0 mg/L. Recently, the rapid development of aquaculture tailwater phosphorus removal technology and phosphorus recovery technology based on physical, chemical, biological and ecological methods has provided strong support for aquaculture tailwater phosphorus removal and recycling. The current aquaculture tailwater phosphorus removal technology has made some progress. However, the advanced removal of phosphorus from the tailwater and phosphorus recovery technology requires further investigation. Enhancing the advanced removal of aquaculture tailwater is essential to ensure the sustainable development of aquaculture. This study classified the phosphorus in the water, examined the principle and current status of aquaculture tailwater phosphorus removal technology, and reviewed the application of phosphorus removal in the tailwater of the current aquaculture model. The principles and current status of phosphorus removal technology in aquaculture tailwater were discussed in terms of physical, chemical, and biological methods of phosphorus removal. The study indicated that the physical method of phosphorus removal technology in aquaculture primarily relies on adsorption and membrane separation technology, in which the high adsorption saturation of adsorbent materials and renewable is the key to adsorption of phosphorus removal, and the physical principle of membrane separation technology is the selective permeability of the membrane. Pollutant retention is achieved through the concentration difference between the two sides of the membrane, hydraulic pressure difference, and potential difference. The current membrane separation technology research methods continue to innovate and generally combine the membrane separation technology and biological method applied to aquaculture tail water phosphorus removal technology. Chemical phosphorus removal technologies such as precipitation, electro-flocculation, crystallization and depth oxidation are important for aquaculture tailwater phosphorus removal technology. These technologies are notable in phosphorus resource recovery and should not be ignored. Biological phosphorus removal technology is a primary method for phosphorus removal in aquaculture tailwater and mainly includes biofilm reactor, Biofloc, microalgae biological purification, bacterial and algal synergistic reactor, artificial wetland and other technologies. Biofilm reactors and Biofloc mainly rely on the role of phosphate accumulating organisms (PAOs) and denitrifying phosphate accumulating organisms (DPAOs), both of which have different processing capacities and biological responses to phosphorus in aerobic, anaerobic and anoxic stages. PAOs absorb phosphorus in aerobic conditions and release phosphorus in anaerobic conditions; DPAOs release phosphorus in anaerobic conditions and absorb phosphorus in the anoxic stage. Microalgae biological purification technology mainly uses the photosynthesis of microalgae and microalgae growth to absorb and remove phosphorus from the water. The microalgae bioreactor is a bacterial-algae synergistic reactor formed by combining microalgae and biofilm reactors to remove phosphorus. Artificial wetlands are a comprehensive phosphorus management method that integrates physical, chemical, and biological methods. This approach is becoming prominent as a crucial technique for phosphorus management in aquaculture tailwater. Current aquaculture modes such as recirculating aquaculture system (RAS), pond aquaculture and other modes, in which RAS mostly use biofilm reactors, bacterial and algal synergistic bioreactors and multi-level integrated aquaculture systems and other treatment methods, and in recent years, artificial wetlands are also gradually applied in the treatment of phosphorus in RAS tailwater. Artificial wetlands are used with sediment and microbial fuel cells to remove phosphorus from aquaculture tailwater. In phosphorus treatment in recirculating aquaculture tailwater, the bioecological method is gradually being used as the main method to treat phosphorus in tailwater, supplemented by physicochemical methods. The pond aquaculture tailwater phosphorus management is also based on bioecological methods, such as 'three ponds and two dams', artificial wetlands, multi-level integrated aquaculture treatment system and other methods to remove phosphorus. This study analyzed the aquaculture tailwater phosphorus removal technology, which can provide new ideas for tailwater phosphorus treatment and phosphorus resource recovery and promote the green development of aquaculture.
The tilt angle of solar active regions (AR) is crucial for the Babcock-Leighton type dynamo models in the buildup of polar field. However, divergent results regarding properties of tilt angles were reported due to their wide scatter, caused by intrinsic solar mechanisms and measurement errors. Here, we mutually validate the magnetogram-based AR tilt angle dataset from Wang, Jiang, & Luo with the Debrecen Photoheliographic Data by identifying common data points where both datasets provide comparable tilt angles for the same AR/sunspot. The mutually validated datasets effectively reduce measurement errors, enabling a more accurate analysis of the intrinsic properties of tilt angles. Our mutually validated datasets reveal that the difference between white-light-based and magnetogram-based tilt angles has no significant difference. Also, the datasets show that an upward revision of average tilt angle ($\barα$) and a downward revision of the tilt scatter ($σ_α$) compared to previous results are necessary, with typical values of about 7$^\circ$ and 16$^\circ$, respectively. The $σ_α$ values demonstrate a strong correlation with AR flux and sunspot area, with the dependency functions re-evaluated using mutually validated datasets. Furthermore, both $\barα$ and the tilt coefficient for the weak cycle 24 are larger than those for cycle 23. This supports the tilt quenching mechanism, which posits an anti-correlation between the cycle-averaged tilt angle and cycle amplitude. Additionally, tilt angle from the mutually validated dataset has a weak non-monotonic relationship with magnetic flux and does not depend on the maximum magnetic field strength of ARs.
Purpose.To characterize the productive and biological features of the first generation crossbreed carp from the crossbreeding of Antoniny-Zozulenets, Galician and Lyubin inbred types of Ukrainian framed and scaly breeds adapted to cultivation in the conditions of Polissiya.
Methodology. The study was conducted at the Lviv Research Station of the Institute of Fisheries of the National Academy of Sciences. The material for the study was crossbred age-0+ and age-1 carps obtained from brood Lyubin (LSC), Galician (GFC) and Antoniny-Zozulenets carps obtained by natural spawning in ponds, according to the following scheme: ♀LSC×♂LSC; ♀LSC×♂AZFC; ♀AZSC×♂LSC; ♀AZFC×♂GFC. The brood stock was kept according to the instructions in the carp breeding. Studies of productive and biological parameters were carried out according to the common methods in fish farming and ichthyology. The heterosis effect for the main productive parameters was calculated by the excess of the corresponding parameter in the crossbreed group over the parameter of the original maternal line. Feeding of age-0+ fish was carried out with ground grain starting from the second decade of July. Winter hardiness of crossbred and pure lines was evaluated by absolute and relative loss of body weight and survival rate. The data obtained in the experiments was subjected to statistical processing in MS Excel (2016). The criteria for the analysis of parameters were their average value and standard error (M±m).
Findings. The study showed that the survival rate of purebred age-0+ carps was 52.4%, with an average weight of 26.79±1.83 g. The yield of crossbred age-0+ fish grown in nursery ponds was 51.3%, but their average weight was the highest — 33.97±4.49 g. The yield of age-0+ fish obtained from crossing ♀AZFC×♂GFC grown in concrete ponds was 55.4% and was the highest among all experimental groups. The survival rate of age-0+ fish obtained from crossing ♀AZSC×♂LSC was 53.1%. The individual average weights of age-10+ carps grown in concrete ponds were close and amounted to 15.39±2.01 and 16.45±1.30 g, respectively, according to the experimental groups. Fish productivity in concrete ponds was 255.8 and 261.9 kg/ha.
The analysis of wintering showed that the yield from the wintering of age-1 LSC and cross-breeding group ♀LSC×♂AZFC was 81.7% and 76.0%, with higher values of the yield of purebred scaly age-1 fish. At the same time, they also had a lower rate, almost 2% weight loss during the winter — 8.9% versus 10.8% in crossbred framed age-1 fish. Age-1 fish of crossbred groups, which were obtained from Antoniny-Zozulenetsk carp females, had a survival rate of 51.3–55.5% with a weight loss of 12.9–13.1%.
Originality. For the first time, the advantages and biological parameters of crossbred groups and individual types of carp from the combination of different structural units, namely Antoniny-Zozulenetsk, Lyubin and Galician inbred types of carps were obtained and studied. Therefore, scientific studies aimed at finding optimal combinations of productive traits of carp, by crossing fish of various structural units not only with desired traits, but also with maximally different genetic characteristics, is particularly important.
Practical Value. The obtained results demonstrate the effectiveness of the use of industrial crossing in modern fish farming practice. Taking into account the belonging of each inbred type to ecological and geographical conditions, when crossing breeds of different geographical origins, an increase in the effect of heterosis is observed. Industrial hybridization and its high efficiency in pond fish farming due to the use of heterosis plays an important role in increasing the fish productivity of pond farms.
Deep learning systems deployed in real-world applications often encounter data that is different from their in-distribution (ID). A reliable model should ideally abstain from making decisions in this out-of-distribution (OOD) setting. Existing state-of-the-art methods primarily focus on feature distances, such as k-th nearest neighbors and distances to decision boundaries, either overlooking or ineffectively using in-distribution statistics. In this work, we propose a novel angle-based metric for OOD detection that is computed relative to the in-distribution structure. We demonstrate that the angles between feature representations and decision boundaries, viewed from the mean of in-distribution features, serve as an effective discriminative factor between ID and OOD data. We evaluate our method on nine ImageNet-pretrained models. Our approach achieves the lowest FPR in 5 out of 9 ImageNet models, obtains the best average FPR overall, and consistently ranking among the top 3 across all evaluated models. Furthermore, we highlight the benefits of contrastive representations by showing strong performance with ResNet SCL and CLIP architectures. Finally, we demonstrate that the scale-invariant nature of our score enables an ensemble strategy via simple score summation. Code is available at https://github.com/berkerdemirel/ORA-OOD-Detection-with-Relative-Angles.
Yugui Zhang, Hongfei Huang, William T. H. Chang
et al.
Citric acid is an organic acid extensively used in feed industry, and AZOMITE is a hydrated aluminosilicate compound rich in rare earth elements and trace mineral elements. This study investigated the supplemental effects of AZOMITE and citric acid individual or in combination on the growth performance, intestinal microbiota, morphology, digestive enzyme activity, serum indexes, and disease resistance of juvenile largemouth bass. Six diets were designed, including the control diet (CON) and the five additive-supplemented diets with the addition of 4 or 8 g/kg citric acid (CA4, CA8), 3 g/kg AZOMITE (A3), and their combined addition as 4 g/kg citric acid + 1.5 g/kg AZOMITE) (C4A1.5) and 8 g/kg citric acid + 3 g/kg AZOMITE (C8A3). Juvenile largemouth bass with initial body weight of 22.01 ± 0.09 g were fed the six diets for 56 days. The results revealed that the combined addition of 4 g/kg citric acid and 1.5 g/kg AZOMITE (C4A1.5) increased weight gain by 7.99% (P<0.05), and decreased feed conversion ratio by 0.07 (P<0.05). The protein retention in the C4A1.5 group and the lipid retention in all additive-supplemented groups were significantly higher than those in the control group (P<0.05). In serum, all additive-supplemented groups showed significantly higher glutathione peroxidase activity than the control group (P<0.05). The activities of superoxide dismutase and catalase in the CA8, A3, C4A1.5, and C8A3 groups were significantly higher (P<0.05), while the concentration of malondialdehyde was significantly lower than those in the control group (P<0.05). Moreover, the total antioxidant capacity in the A3 and C4A1.5 groups, and lysozyme activity in the A3, C4A1.5, and C8A3 groups were significantly increased when compared to the control group (P<0.05). In digestive enzyme, the protease activity in the A3, C4A1.5 groups, and amylase activity in the CA4, CA8, and C4A1.5 groups were significantly higher than those in the control group (P<0.05). In intestinal microbiota, Firmicutes abundance was elevated in all additive groups, while the Fusobacteriota and Plesiomonas shigelloides abundance were decreased. In the intestinal histology, the CA8, A3, and C4A1.5 groups showed significantly higher villus height than the control group (P<0.05). After the infection with Aeromonas hydrophila, the cumulative mortality of all additive-supplemented groups was significantly lower (P<0.05), and the C4A1.5 group demonstrated the lowest mortality. In conclusion, the combined supplementation of 4 g/kg citric acid + 1.5 g/kg AZOMITE increased the growth, antioxidant, immune capacity, improved the intestinal morphology and microbial flora of juvenile largemouth bass, and promoted the resistance against Aeromonas hydrophila infection.
The growth of catfish seeds can be influenced by many factors including high water and seed stocking density. The research objective was to analyze the effect of high air and stocking density of different fish on the growth and maintenance of Sangkuriang catfish fry. This type of quantitative research with an experimental approach. The research was an experiment using a completely randomized design (CRD) factorial. Data processing uses SPSS Version 22 with two-way ANOVA analysis if there are differences, it will be followed by Tukey HSD. The research analysis showed that there was an effect of varying stocking density treatments on the survival of fish fry and absolute growth, while the high air treatment only had an effect on the survival of Sangkuriang catfish fry. The research yielded a water height of 13 cm and a stocking density of 15 individuals/liter was the treatment with the highest survival rate for catfish seeds with a value of 74.4%, while for exclusive weight growth, the treatment was 10 cm water height and a stocking density of 15 individuals/liter of 0.94 g.
In brackishwater aquaculture, pond engineering is essential to meet the cultured species' bio-physical requirements and potentially minimizing social and environmental impacts. This study evaluated the suitability of pond engineering designs and pond, dyke, and canal construction at family-run, extensive brackishwater aquaculture farms in Barru regency of South Sulawesi, Indonesia. Soil properties, topography, hydrological data, field surveys, and high resolution (0.6 m) Quickbird imagery were used to assess the suitability of local pond engineering designs and the efficiency of canals. The study shows that in 752 of the evaluated pond units (430 ha), about 70% of pond beds were not constructed at the optimal pond elevation. Basic engineering requirements for pond layout and dyke and canal designs were not addressed in more than 70% of the pond units. Cease-to-flow conditions commonly occur due to the sedimentation of canals. Flows are also attenuated due to collapsed dykes. Farmers disregarded soil limitations and the impacts of tidal conditions and wave regimes. It is unlikely that shrimp and fish production in the region can increase without significant improvements in pond engineering. The problems identified by the study are not unique to Barru; they also occur in other extensive aquaculture areas in Indonesia and the region. Increased awareness of the need for improved pond engineering techniques is urgently needed to safeguard the economic and environmental sustainability of Indonesia's valuable aquaculture industry.
The topological $θ$-angle is central to the understanding of a plethora of phenomena in condensed matter and high-energy physics such as the strong CP problem, dynamical quantum topological phase transitions, and the confinement--deconfinement transition. Difficulties arise when probing the effects of the topological $θ$-angle using classical methods, in particular through the appearance of a sign problem in numerical simulations. Quantum simulators offer a powerful alternate venue for realizing the $θ$-angle, which has hitherto remained an outstanding challenge due to the difficulty of introducing a dynamical electric field in the experiment. Here, we report on the experimental realization of a tunable topological $θ$-angle in a Bose--Hubbard gauge-theory quantum simulator, implemented through a tilted superlattice potential that induces an effective background electric field. We demonstrate the rich physics due to this angle by the direct observation of the confinement--deconfinement transition of $(1+1)$-dimensional quantum electrodynamics. Using an atomic-precision quantum gas microscope, we distinguish between the confined and deconfined phases by monitoring the real-time evolution of particle--antiparticle pairs, which exhibit constrained (ballistic) propagation for a finite (vanishing) deviation of the $θ$-angle from $π$. Our work provides a major step forward in the realization of topological terms on modern quantum simulators, and the exploration of rich physics they have been theorized to entail.
Abstract Outbreaks of fish bacterial diseases have become quite frequent with the intensification of practices in aquaculture. Vaccination has become an increasingly important prevention strategy against infectious agents in farmed fishes. However, only a few licensed fish bacterial vaccines are commercially available worldwide, and the majority of them are conventional inactivated vaccines. The use of bacterial ghosts (BGs) as novel candidate vaccines has attracted increasing attention from researchers. BGs are nonliving empty cell envelopes mainly derived from gram-negative bacteria. Pores in gram-negative bacteria are formed most commonly through the strictly controlled expression of bacteriophage PhiX174 lysis gene E, whereas pores in gram-positive bacteria can be formed through minimally inhibitory gentle chemical protocols. In biological protocols, the temperature-sensitive λ system has been widely used for quick and efficient lysis without the need for any addition of chemical inducers. To produce BGs with enhanced safety, the incorporation of the staphylococcal nuclease A gene, holin-endolysin system, or antimicrobial peptide genes into gene E-mediated lysis cassettes has been applied to improve lysis efficiency. The ghosts of a few fish pathogenic bacteria, such as Edwardsiella spp., Aeromonas spp., Vibrio spp., and Streptococcus spp., have been successfully developed by gene E-mediated lysis, which maintain the original cell morphology but eliminate genetic contents. Although the lysis efficiency of these BGs does not reach 100%, the lyophilized BGs were free of any living cells. These lyophilized BGs not only have high biological safety for fish, but also can induce stronger humoral, cellular and mucosal immune responses compared to conventional inactivated vaccines. Moreover, BGs are easy to produce in large quantities by fermentation without laborious purification procedures and easy to administer through oral or immersion immunization. Therefore, BGs are good fish vaccine candidates and can be engineered to display heterologous antigens or deliver DNA for use as multivalent vaccines against fish pathogen infection. Yet, completely inactivation was not achieved by the gene E-mediated lysis procedure, how to improve the lysis efficiency of BGs is an important problem for BG production. It is believed that the BG system will play an increasingly important role in the prevention and control of fish diseases with further research and continuous biotechnological development.
The results obtained for the juveniles of Liza abu showed that in high salinity there was a decrease in food intake (1.88%) compared to low salinity (7g/l) and tap water (1.5g/l). Also the total digestibility decreased 10% with increasing salinity from1.5 to 15 7g/l as a result of increasing the evacuation rate, where values reached 88.39% and 90.3% from total faces weight in salinity 7 and 15 g/l respectively after 18 hrs.
We present a semianalytical scheme for the design of broad-angle multichannel metagratings (MG), sparse periodic arrangements of loaded conducting strips (meta-atoms), embedded in a multilayer printed circuit board configuration. By judicious choice of periodicity and angles of incidence, scattering off such a MG can be described via a multi-port network, where the input and output ports correspond to different illumination and reflection directions associated with the same set of propagating Floquet-Bloch modes. Since each of these possible scattering scenarios can be modelled analytically, constraints can be conveniently applied on the modal reflection coefficients (scattering matrix entries) to yield a diffusive response, which, when resolved, produce the required MG geometry. We show that by demanding a symmetric MG configuration, the number of independent S parameters can be dramatically reduced, enabling satisfaction of multiple such constraints using a single sparse MG. Without any full-wave optimization, this procedure results in a fabrication-ready layout of a multichannel MG, enabling retroreflection suppression and diffusive scattering from numerous angles of incidence simultaneously. This concept, verified experimentally via a five-channel prototype, offers an innovative solution to both monostatic and bistatic radar cross section reduction, avoiding design and implementation challenges associated with dense metasurfaces used for this purpose.