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Copyright of Acta Scientiarum Naturalium Universitatis Sunyatseni / Zhongshan Daxue Xuebao is the property of Sun-Yat-Sen University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

ABSTRACT Myctophids play an essential role in the marine ecosystem, linking the surface to the mesopelagic layer through diel vertical migration, and contributing to carbon sequestration. However, basic knowledge of their biology and distribution is still limited. Here, we described the length and age distribution, growth and otolith morphometrics for one of the most abundant myctophid fish of the Northeast Atlantic, the Krøyer's lantern fish Notoscopelus kroyeri (Malm, 1861). Individuals were sampled opportunistically by pelagic trawls during the International Ecosystem Summer Survey in the Nordic Seas (IESSNS) conducted in July 2020 and 2021. We provide the length–weight and otolith–fish size relationships and the size distribution for 336 N. kroyeri individuals collected along Iceland's south and west shelf, the Iceland Basin, and the Irminger Sea. Fish were primarily distributed along the Reykjanes Ridge and the continental shelf at depths between 0 and 550 m. Three size groups, corresponding to three different age groups, with individuals from 2 to 9 years old, were detected across sampling areas. We found positive allometric growth during both sampling years. Linear regressions were significant between otolith length, width and area, and fish length and weight, with adjusted r2 values ranging between 0.93 and 0.94. This study provides new information on the biology and distribution of one of the most abundant mesopelagic species in south Icelandic and surrounding waters. [ABSTRACT FROM AUTHOR]

AbstractFish viscera, a fish processing by-product, is currently underutilized, despite its complex composition of high value-added components, such as proteins, lipids, and polysaccharides. This work explores the potential for revalorizing fish viscera as a sustainable source of proteins, lipids and polysaccharides in the food industry. Furthermore, their potential food applications and future perspectives are discussed. Fish viscera, constituting 12–18% of the total fish weight, is abundant in proteins, lipids, and polysaccharides. Protein hydrolysates derived from fish viscera exhibit diverse bioactivities, such as antioxidant, ACE-inhibitory, and antibacterial activities. Various enzymes with high stability properties can be extracted from fish viscera. Moreover, fish viscera-derived lipids are abundant in saturated/unsaturated fatty acids and phospholipids, which can exhibit excellent bioactivities such as immune regulatory, anti-inflammatory, lipid metabolism-regulatory and anti-tumor activities. Additionally, polysaccharides present in fish viscera display anticoagulant and antithrombotic activities. Overall, fish viscera have great potential as a good source of proteins, lipids and polysaccharides. [ABSTRACT FROM AUTHOR]

A 12-week feeding trial assessed the impact of protein-to-lipid ratios (P:L) on the growth, feed and protein utilization, digestive enzyme activity, and fillet composition of juvenile striped bass (Morone saxatilis) raised at summer local seawater temperature conditions (21 °C). A 3 × 2 factorial design, using three protein levels (40, 44, and 48%) and two lipid levels (12 and 16%) resulting in six diets (40:12, 44:12, 48:12, 40:16, 44:16, and 48:16) was used. Hatchery-reared fish with an initial weight of 11.4 ± 0.2 g were used. Laboratory-formulated experimental diets were randomly assigned to triplicate groups of 22 fish in 500-L tanks connected to a recirculating seawater (35.4 ± 3 ppt) system, and fish were fed manually to apparent satiation four times a day. Survival rates were higher than 96% across all treatments, remaining unaffected by dietary treatments. Fish fed the 44:12 and 48:12 diets resulted in significantly higher weight gain (WG) (274.1 ± 18.4 and 306.8 ± 19.8, respectively), final body weight (FBW) (42.4 ± 1.2 g and 47.1 ± 2.4 g, respectively), and specific growth rate (SGR) (1.6 ± 0.06 and 1.7 ± 0.06, respectively). Diets with 12% lipid resulted in feed conversion rate (FCR) values closer to 1, and the 48:16 (1 ± 0.03) treatment resulted in no significant differences compared to the 12% lipid dietary treatments. Similar trends were observed for protein efficiency ratio (PER), with comparable values for the 40:12 (2.0 ± 0.1), 44:12 (2.2 ± 0.1), 48:12 (2.0 ± 0.1), and 48:16 (2.1 ± 0.1) treatments. A strong relationship between dietary P:E ratios and SGR, PER, and FCR was observed among treatments, which helped explain the interactions between protein and lipid obtained. An estimated dietary P:E ratio between 11 and 12 is suggested for efficient protein and feed utilization for this species under our culture conditions. The apparent digestibility coefficient (ADC %) was significantly higher in the 12% lipid diets (65.01 ± 3.06%), influenced solely by lipid content. Enzyme activity for trypsin and chymotrypsin in the pyloric caeca (PC) and intestines (I) were higher in the 48:12 treatment (893.5 ± 18.1, 1087.3 ± 55.5, 12.2 ± 0.3, and 8.3 ± 0.2 Units/g organ, respectively). L-aminopeptidase activity (PC) was higher in the 48:12 treatment (1007.7 ± 101.8 Units/g organ), while L-aminopeptidase (I) had higher values in the 48:16 treatment (2217.2 ± 161.3 Units/g organ). In the case of lipase (PC), activity was higher in the 12% lipid treatments, while in the intestine, the highest activity was recorded in the 44:12 treatment (1084.4 ± 87.0). The activity of proteases, except for L-aminopeptidase (PC), directly correlated with improvements in SGR, PER, feed intake (FI), and FCR which helps explain the observed results. The Hepatosomatic index (HSI) was significantly higher in the 40:12 treatment while the liposomatic index (LSI) and viscerosomatic index (VSI) indices showed no significant differences between the 40:12, 44:12, 48:12, and 48:16 treatments, respectively. Importantly, the lipid content in the fillet did not significantly decrease with reduced lipid content in the diet, an important issue for market acceptance. Results from the present study suggest an optimal P:L ratio of 48:12 for juvenile striped bass raised in seawater under local summer conditions (21 °C). [ABSTRACT FROM AUTHOR]

This study investigated the influence of visual and chemical stimuli from live prey on juvenile Florida pompano (Trachinotus carolinus) growth. Twelve tanks within four independent recirculating systems housed fish of similar weight (obtained from a commercial fish farm) in groups of ten. Prior to their morning feeding (they were fed twice daily at 10 h and 16 h with commercial pellets), fish were exposed to one of four stimuli: visual and chemical cues from Artemia, mole crab, feed pellets (control for stimuli), or seawater (control for procedures). Key growth parameters were monitored weekly for seven weeks, including feed intake, weight gain, and specific growth rate (SGR). Fish exposed to Artemia and mole crab stimuli exhibited significantly higher feed intake (23.11 ± 1.37 and 23.45 ± 1.38 g/fish), weight gain (169.28 ± 7.59 and 172.75 ± 12.57%), and SGR (2.02 ± 0.05 and 2.04 ± 0.09% day−1) compared to those exposed to feed pellets (stimuli control) and seawater (procedures control): feed intake (20.81 ± 0.684 and 19.30 ± 0.39 g/fish), weight gain (136.25 ± 4.51 and 140.23 ± 6.36%), and SGR (1.75 ± 0.03 and 1.78 ± 0.05%.day−1). These findings highlight the importance of visual and chemical cues from live prey as feeding incitants and stimulants. By enhancing feeding motivation and intake, these stimuli promote growth and potentially improve the welfare of juvenile Florida pompano. [ABSTRACT FROM AUTHOR]

Simple Summary: The limited understanding of the fractionation of rare earth elements (REEs) in fish has hindered the effective use of biomonitoring to assess REEs contamination in aquatic environments. Guangzhou City, which faces widespread emissions of REEs, urgently needs biomonitoring of REEs. Therefore, this study took Guangzhou City as a case study and conducted wild fish collections to investigate the bioaccumulation and fractionation of REEs. Additionally, the associated health risks were evaluated to guide fish consuming. This study confirmed the different REEs bioaccumulation and fractionation among 11 fish species. The bioaccumulation of REEs was found to be a process that could mitigate REEs fractionation. The bioaccumulation and fractionation of REEs among fish with feeding behaviors and living habitats were determined to be specific, so that REEs bioaccumulation and fractionation could be used for tracing the environmental behaviors of fish. Food sources should be treated as the critical regulator in varying REEs bioaccumulation and differentiation. The overall low content of REEs in wild fish shows their consumption should not pose a relevant risk. In this study, the total content of REEs ranged from 1.32 to 67.74 μg/kg, with a predominant presence of light REEs. The ΔEu and ΔCe values, which exceeded and approached 1, respectively, indicated positive Eu anomalies and low Ce anomalies. Wild fish were categorized into high-, medium-, and low-REEs-bioaccumulation groups using cluster analysis. Higher LRs/HRs and ΔEu values, coupled with lower ΔCe values, in fish from the high-bioaccumulation group suggested that increased bioaccumulation mitigated fractionation. Omnivorous fish with higher REEs levels and lower LRs/HRs indicated broader feeding sources may enhance REE bioaccumulation and diminish fractionation. Elevated REEs concentrations and LRs/HRs in demersal fish highlighted a preferential accumulation of light REEs in the benthic environment. Smaller fish with higher REEs levels but lower LRs/HRs were likely associated with complex feeding sources. Regression analysis revealed that fish with lengths and weights of less than 18 cm and 130 g, respectively, were more susceptible to REEs bioaccumulation. Despite higher ADI values indicating a greater risk for children and Pelteobagrus fulvidraco, all ADI values within 70 μg/(kg·d) suggested that fish consumption poses no risk. This study confirmed that the fractionation of REEs in fish can be used to trace their bioconversion. [ABSTRACT FROM AUTHOR]

The latest strain of Oreochromis niloticus is an altered ecological adaptation for sustainable aquaculture and is necessary to sustain stocking density and reduce physiological stress of the new strain. The present study aimed to determine the optimum stocking density, biological performance, and economic efficiency of the Nile tilapia. The 14,000 healthy seeds and uniform weight (40 ± 2.4 g) sex‐reversed Oreochromis niloticus were stocked in four cages, which are cage (1) 20 fish/m3, cage (2) 30 fish/m3, cage (3) 40 fish/m3, and cage (4) 50 fish/m3. The fish were fed 30% dietary protein and feeding frequency three times per day and the feeding rate adjusted according to the fish body weight. Results showed a significantly higher growth, weight gain, and specific growth rate in Nile tilapia stocking density on cage (1), 20 fish/m3 and cage (2), 30 fish/m3 compared to cage (3), 40 fish/m3 and cage (4), 50 fish/m3 (p < .05). The survival and growth rate showed an inverse relationship with stocking density. The feed conversion ratio (FCR) is the lowest in cage (1) and cage (2), which is significantly different from those of other cages (p < .05). The profit index (%) was significantly higher at low density. There was no significant variation in the HSI, VSI and CF. The digestive enzymes such as lipase and amylase were secreted highly in the cages (3) and (4) but high protease was secreted in cage (1). The lipid, ash, and protein of the whole fish were reduced to a lower density, but the moisture levels in the fish bodies raised significantly (p < .05) with increasing stocking density. The phenomenal regression indicates that 25–35 fish/m3 are optimum stocking density for Nile tilapia in the cage culture system. The current study has made significant step toward optimizing the stocking density of a new strain and developing cage culture in Pakistan. [ABSTRACT FROM AUTHOR]

Body length and weight are key parameters measured to provide information about the growth and condition of larval, juvenile, and adult fishes from both the wild and aquaculture. The goal of this study was to evaluate the effects of preservation in formalin and alcohol on juvenile rainbow trout, Oncorhynchus mykiss (Walbaum) standard body length (SL) and weight changes. Standard length (19.43–32.98 mm SL) decreased after 60 days of preservation by an average of 2.98% in 96% alcohol and 2.26% in 10% formalin. In contrast, fish body weight (0.094–0.63 g) decreased in alcohol (31.22%) but increased in formalin (11.65%). These percentage values can be used as correction factors, with the exception of fish body weight in alcohol since the size of individuals affected the magnitude of change. Accordingly, a correction formula accounting for fish weight must be applied (fresh weight (g) = -0.0363 + 1.667 × preserved length). Changes in fish length and body weight in different preservatives resulted in significant differences in the Fulton condition factor, with underestimation in alcohol (fresh F = 1.58; preserved F = 1.20) and overestimation in formalin (fresh F = 1.60; preserved F = 1.92). [ABSTRACT FROM AUTHOR]

Water quality management is a critical factor in recirculating aquaculture systems (RASs) that significantly influences the growth and health of fish. The present research aimed to investigate the effects of humic acid (HA) added at three concentrations (0, 1.5, and 3 mg L−1) to water on total ammonia nitrogen (TAN) removal efficiency of biofilter unit, growth performance, and some blood biochemical indices of Nile tilapia (Oreochromis niloticus) in a water recirculating system. The Nile tilapia fish with an average weight of 83.44 ± 1.32 g were cultured in nine individual experimental units for 30 days. The removal efficiency of the biofilter for TAN reached to 81.23% and 82.76% in the systems with 1.5 mg L−1 and 3 mg L−1 HA, respectively. The systems with HA had higher nitrate (NO3−) concentration than the the system without HA (control) (p < 0.05). HA adding to the water increased the fish final body weight and the specific growth rate (SGR) compared to the control group (p < 0.05). The feed conversion ratio (FCR) in the HA-groups was significantly lower than the control (p < 0.05). The highest crude protein content of muscle tissue was observed in the fish cultured in the system with 3 mg L−1 HA (p < 0.05). There were no significant differences in the plasma alanine aminotransferase (ALT) and aspartate aminotransferase (AST) concentrations among treatment groups (p > 0.05). The plasma glucose concentration was significantly lower in the fish exposed to HA compared to the control (p < 0.05). The highest plasma triglyceride concentration was recorded in the HA-3 mg L−1 (p < 0.05). These results indicated that the addition of low-cost commercial HA to RASs has a high potential to improve water quality and fish growth performance. [ABSTRACT FROM AUTHOR]

Probiotic administration has the ability to increase broodstock performance and aquaculture productivity. The effect of dietary probiotics Bacillus cereus NP5 on the reproductive performance of female Clarias gariepinus and the survival of the resulting larvae was investigated in this study. Female fish with an initial weight of 553 ± 27.41 g, were placed in 12 hapas and fed for 12 weeks on three experimental diets supplemented with different concentrations of probiotics: 0 (control), 106 (B6), and 108 CFU g-1 feed (B8). This study found that B8 fish had higher protein retention (p<0.05), but body weight was comparable among treatments (p>0.05). Furthermore, probiotic diets increased digestive enzyme activity (p<0.05) such as amylase, protease, and lipase. Different doses of B. cereus NP5 probiotic significantly (p<0.05) affected intestinal villi height, but it did not increase villi length or intestinal diameter. Throughout the rearing period, the probiotic groups showed higher estradiol levels, and total cholesterol levels (p<0.05), stimulated early ovarian development, leading to higher GSI, HSI, and percentage of developed eggs (p<0.05). When compared to B6 and the control, the B8 treatment resulted in significantly higher fecundity, hatching rate, and larval survival (p<0.05). The results obtained support the hypothesis that probiotics could improve the reproductive performance and larval survival of female C. gariepinus. [ABSTRACT FROM AUTHOR]

This study analyzed the length–weight relations and condition factors of 13 species belonging to three highly endemic genera: Oxynoemacheilus (6), Seminemacheilus (2) and Cobitis (5). Fish were sampled in several streams and lakes using a backpack electroshocker. Analyses were based on a total number of individuals, which was n = 304. A linear regression model was applied to determine the relationship between fish length and weight. The coefficient of determination (R2) ranged from 0.950 to 0.980 for all populations (p < 0.05). Allometric coefficient 'b' values ranged from 2.498 to 3.201 for Oxynoemacheilus, from 2.970 to 2.127 for Seminemacheilus, and from 2.111 to 3.076 for Cobitis populations. Fulton's condition factor for Oxynoemacheilus, Seminemacheilus and Cobitis ranged from 0.391 to 3.080. This study addresses gaps in LWR and CF information for a number of ecologically important freshwater fish species. It is expected that the results of this research provide baseline data for further fisheries management studies and may support conservation studies of related species. [ABSTRACT FROM AUTHOR]

The study aimed to investigate the effects of different feeding rates on the growth, muscle composition, intestinal digestive enzyme activities, and intestinal microbiota composition of juvenile crayfish (Procambarus clarkii). A total of 240 crayfish with an initial body weight of 8.33±0.50 g were randomly distributed into five groups, and each group had three replicates. The five groups corresponded to five different feeding rates of 2%, 4%, 6%, 8%, and 10% body weight per day (BW/day). The feeding trial lasted for six weeks. The results showed that the final body weight (FBW), weight gain rate (WGR), and specific growth rate (SGR) first increased when the feed rate increased from 2% to 6 % (P<0.05) and then showed a decreased trend with the further increase of the feeding rate, but no significant differences were observed. The feed conversion ratio (FCR) increased with a rise in feeding rate, which reached a peak at the feeding rate of 10% (P<0.05). The survival rate (SR), hepatosomatic index (HSI), and condition factor (CF) were unaffected by the feeding rates (P>0.05). The moisture, crude protein, crude fat, and ash contents of crayfish muscle remained unchanged among all feeding rate groups. Intestinal activities of lipase and amylase increase with the feeding rate (up to 6%) increasing (P<0.05). The ACE and Chao indices in the groups fed at 2% of feeding rate were significantly lower than those at a feeding rate of 10% (P<0.05). The relative abundance of Firmicutes in the groups fed at feeding rates of 4%, 6%, and 8% was higher than that in other groups (P<0.05), Citrobacter in the group fed at feeding rate of 6% was lower than that in different groups (P<0.05). The intestinal microbiota primarily functions in connection to amino acid, carbohydrate, and vitamin metabolism. Therefore, the optimum feeding rate could be 6.0% of the feeding rate of juvenile P. clarkii. [ABSTRACT FROM AUTHOR]

Sophora flavescens is considered to be of various medicinal and economic importance. Previous studies have shown that it has antibacterial, antioxidant, and immune‐enhancing functions. To explore the full potential of S. flavescens in fish feed development, we investigated the effects of different levels of S. flavescens added to the diet on the growth performance, haematological indices, and the intestinal bacterial community of Nile tilapia (Oreochromis niloticus). The feeding trial lasted for 56 days, and the initial weight of the fish was 40.00 ± 5.00 g. Nile tilapia were randomly divided into six groups: a control group (CN) and five S. flavescens supplementation groups (0.02%, 0.04%, 0.08%, 0.16%, and 0.3% [w/w] of S. flavescens in diet). The growth performance of fish increased first and then decreased with the increase of S. flavescens supplemental level. Compared with other experimental groups, the growth performance of fish supplemented with 0.08% S. flavescens was significantly improved (p < 0.05). Haematological indices exhibited that erythrocyte (RBC), along with leucocyte (WBC) indices, exhibited a secondary trend of increasing and then decreasing with the increase of S. flavescens, reaching the highest level at 0.08% (p < 0.05). However, mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH), and mean corpuscular haemoglobin concentration (MCHC) exhibited a secondary trend of first decreasing and then increasing with the increase of S. flavescens and reached the lowest value at 0.08% (p < 0.05). Compared with the CN, alkaline phosphatase (AKP) significantly decreased and changed when the additional amount of S. flavescens was 0.04% in each treatment group (p < 0.05). In another way, the gut microbial profiles revealed that Bacteroides dominated the gut communities, and compared with the control group, two uncultured bacteria were suppressed. In addition, when the supplemental level of S. flavescens was more significant than 0.04%, the proliferation of Arcobacter cryaerophilus, Solibacillus silvestris, and Escherichia sp. in the gut of Nile tilapia was promoted. The results revealed that S. flavescens, as an additive to the Nile tilapia diet with levels ranging from 0.04% to 0.08%, can enhance the growth performance and immunity and promote the proliferation of intestinal beneficial bacteria of Nile tilapia. [ABSTRACT FROM AUTHOR]

The degradation of environmental DNA (eDNA) and its release from fish were investigated in laboratory experiments for seven salmonid fishes. The eDNA concentration in experimental tanks without fish decreased exponentially, with a higher rate of decline observed under higher water temperature conditions. When a fish was introduced into a tank, the eDNA concentration was positively correlated with the length and weight of the fish. [ABSTRACT FROM AUTHOR]

The number of artisanal fishers and consequently their catch in the Sava River have been declining significantly for years. The aim of this study is therefore to examine how this affects the average weight of the most important fish species caught. The average weight increased significantly for bream Abramis brama (P < 0.01), pike-perch Sander lucioperca (P < 0.01) and wels catfish Silurus glanis (P < 0.05), while this was not the case for common carp Cyprinus carpio and pike Esox lucius (P > 0.05). Although recreational anglers also catch fish in the same waters, together with the two groups of fishermen from Bosnia and Herzegovina from the other bank of the river, it is expected that the average weight of the main fish caught will not decrease under the current circumstances. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Fisheries is the property of University of Tehran and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Six 0.1‐ha earthen ponds with 45 kW/ha of aeration capacity were stocked with hybrid catfish (Ictalurus punctatus x I. furcatus) ranging from 15,000 to 90,000 fish ha−1 in 15,000 fish ha−1 increments to analyze the effect of nitrogen loading on ammonia accumulation and fish production. Minimum dissolved oxygen (DO) concentration was maintained above 3.0 mg O2 L−1 to prevent hypoxia‐induced appetite reduction. Stocking density did not impact survival but decreased average fish harvest weight and increased food conversion ratio (FCR). Gross production increased with stocking density and ranged from 7249 to 35,674 kg ha−1. Average total (TAN) and un‐ionized ammonia (NH3) were not different among stocking densities despite greater nitrogen inputs in ponds with higher feeding rates. Nitrite (NO2−) and nitrate (NO3−) concentrations were significantly higher in ponds with higher stocking densities, suggesting that nitrification increased with nitrogen loading. Phytoplankton assimilation of ammonia is the primary ammonia removal process in traditional catfish ponds with modest fish densities and feeding rates. However, in intensively aerated ponds with high feeding rates, nitrification can become an important process for ammonia removal. These data indicate that small earthen hybrid catfish ponds with high aeration capacities can increase catfish production without ammonia accumulating. [ABSTRACT FROM AUTHOR]

This research evaluated the suitability of commercially available larval feeds, Otohime B2 (OB2), Aller Infa (AI), and Aqua Start (AS), and one Experimental Feed (EF), for the weaning of largemouth bass (Micropterus salmoides), LMB. Feeds were presented with various ?-3 fatty acid levels/bioavailability (high in OB2 and AI), fat percentage (high in OB2 and AS), free amino acid and short peptide (FAA + SP) levels (high in OB2), and various soluble protein (SPR) levels (high in AS and EF). Fish were co-fed Artemia plus OB2 from the 19th to 22nd day post-hatching (DPH), then Artemia in addition to one of the four above diets for seven days, with complete Artemia removal on the 30th DPH. Fish were sampled on the 32nd DPH. Morphometry, digestive enzyme activities, hormonal status, skeleton, muscle development, and potentially pathogenic Flavobacterium spp. levels were estimated. Survival was high (96% or more) in all the weaning regimes. Weaning to OB2 was linked to a fast fish growth rate (14.29%/day), while both OB2 and AI supported the skeleton development. Weight gain correlated with total fat, ash levels, free amino acids, and short peptide levels in the diet. Larvae weaned to soluble proteinrich AS and EF showed the lowest fish weight gain and skeleton development, and lower growth of potentially pathogenic Flavobacterium spp. This research suggests that the weaning diets for largemouth bass should have a balanced protein content and quality while allowing for the inclusion of fewer marine ingredients. [ABSTRACT FROM AUTHOR]

Copyright of Science & Technology of Food Industry is the property of Science & Technology of Food Industry Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background Result Conclusion Elevated potentially toxic elements (PTEs) in aquatic products could threaten the health of ordinary consumers. Levels of chromium (Cr), arsenic (As), lead (Pb), and mercury (Hg) in Cyprinus carpio in karst plateau freshwater Lake, Caohai Lake, China were quantified using inductively coupled plasma mass spectrometry (ICP‐MS) and evaluated using a risk method with Monte Carlo simulation.Levels of Cr, As, Pb, and Hg in muscle tissue were substantially lower than those in viscera. The maximum concentration of muscle‐bound Cr, As, Pb, and Hg were less than the standard references set by Chinese Food Codex (GB 2762‐2022). The levels of Cr, As, Pb, and Hg in muscle tissue were independent of fish weight and length. The hazard index of all investigated elements in muscle tissue were less than one for adults and children, whereas the target hazard quotients of muscle‐bound PTEs for children were higher than those for adults. Results indicated that exposure duration was the largest contributor to the hazard quotient of Cr, As, and Hg, whereas the concentration of Pb in muscle was the most sensitive factor affecting the variation in hazard quotient of Pb.There is no risk related to the normal intake of muscle‐bound Cr, Pb, As and Hg with the consumption of Cyprinus carpio. A better definition of the probability distribution for exposure duration and PTEs concentration could result in a more accurate hazard quotient. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Aim: Many fish species can harbour a wide range of pathogenic agents in their tissues. Of many pathogens, the parasitic nematode of genus Contracaecum, which resides in the tissues of fish species, can results in fish‐borne infections in humans. This study was planned to assess consumers' awareness of fish‐borne zoonoses in the fishing sites of Lake Chamo, Arba Minch, Ethiopia. The study was also aimed at demonstrating the zoonotic nematode, Contracaecum parasites in the Oreochromis niloticus and Lates niloticus fishes collected from Lake Chamo, Arba Minch, Ethiopia. Methods and Results: Assessment of awareness about fish‐borne zoonoses was conducted in randomly selected participants (n = 162) using face‐to‐face interviews via a structured and semi‐structured questionnaire. Besides, 70 fishes (O. niloticus = 35 and L. niloticus = 35) were examined for the presence of larva of Contracaecum and other anisakid genera through standard dissection, pepsin‐hydrochloric acid digestion and microscopic observation. Consumers have inadequate awareness about fish‐borne zoonoses based on the answers they provided to the questions. The majority of respondents (82%) consume raw fish in the area. Of these, a significantly higher proportion were male (p < 0.001), completed their elementary or high school (p = 0.004), Orthodox Christian (p = 0.044), fishermen (p < 0.001) and participants without previous information about fish‐borne zoonoses (p < 0.001). Overall, of examined fishes (n = 70), n = 15 (21.4%, 95% CI, 12.8–33.2) were infected with Contracaecum larva. A significant (p = 0.028) higher infection prevalence was noted in L. niloticus (34.3%, 95% CI, 19.7–52.3) compared to O. niloticus (8.6%, 95% CI, 2.2–24.2). A unit gram addition in the total weight of fish would significantly raise the risk of Contracaecum infection by 1% (p < 0.001). Conclusions: The presence of Contracaecum, a zoonotic nematode in the fishes, which are often preferred by consumers for raw dishes, designates a high risk of possible fish‐borne infections in the area. Thus, providing education and training for fishermen, visitors of the area, and local people who visit the area for fish consumption, it is inevitably important to minimize the risk. Furthermore, health workers should suspect fish‐borne infections, such as anisakidosis in patients who have a history of raw fish consumption in Arba Minch, Ethiopia. [ABSTRACT FROM AUTHOR]

This study evaluated the effect of four different feeding regimes on the growth, health, economic effiency and perception of aquaculturists regarding Oreochromis sp. in the Guayas Province, Ecuador. Four treatments based on different feeding regimes were established: T1, once a day with a daily interval; T2, once a day with an interval every two days; T3, twice a day with a daily interval; and T4, twice a day with an interval every two days. Growth parameters such as total fish weight gain, average daily weight gain, daily feed intake, expected weight gain for each daily feed intake, feed conversion ratio, protein efficiency, and protein productive value were measured. Health parameters included serum total protein content, albumin, serum globulins, cholesterol, triglycerides, and glucose levels. Economic efficiency parameters such as feed cost and feed cost per kilogram of weight gain were also assessed. Additionally, surveys were conducted with aquaculturists to assess the perception of aquaculture farmers regarding the importance of growth factors, fish health, and economic efficiency in the selection of feeding regimes for Oreochromis sp. The results indicated that treatment T3 was the most effective in maximizing growth; treatment T1 excelled in fish health; and treatment T2 was the most economically efficient. In conclusion, the choice of feeding regime will depend on the farmers' priorities, with a general trend, according to the survey, toward economic efficiency and growth, while fish health, although relevant, is a secondary priority. [ABSTRACT FROM AUTHOR]

Sillago muktijoddhai is a marine fish found along the Bay of Bengal in Bangladesh and the coast of India. However, detailed information on its reproductive biology, length-weight relationship, and feeding habits is lacking. To fill this gap in literature, a research was conducted from August 2022 to October 2023, during which 444 individuals were collected from the Cox's Bazar coast of the Bay of Bengal, Bangladesh. The total length and weight of the fish ranged from 51.23 to 200.5mm and 2.47 to 71.73g, respectively. Analysis of the sex ratio revealed a dominance of males over females, with a ratio of 1.36:1 (X² = 10.41, P< 0.05). The condition factors indicated that males exhibited a better growth pattern than females. The gonadosomatic index suggested that the peak breeding season occurs in November. Histological observations identified four distinct stages of gonadal development for males: immature, maturing, ripe, and spent. For females, the stages were immature, maturing, mature, and ripe. The absolute fecundity ranged from 6,164 to 30,555 eggs per ovary, with a mean value of 12,176 ± 1,050. The regression coefficient (b) for the length-weight relationship was 3.213, indicating a positive allometric growth pattern. Morphometric analysis of the mouth and relative gut length revealed that S. muktijoddhai is a bottom feeder with carnivorous habits. Gut content analysis showed that crustaceans formed the major component of its diet, although zooplankton, gastropods, bivalves, and sand were also present. [ABSTRACT FROM AUTHOR]

Background: Sexual function is one of the most important aspects of life and is likely to be affected by the side effects of antihypertensive drugs. This study aimed to evaluate the effect of propranolol and prazosin on the sexual performance of female three-spot gourami. Methods: In this study, 84 female three-spot gourami were randomly divided into seven groups, including a control and six experimental groups. The experimental groups were injected with prazosin or propranolol at doses of 1, 2, and 4 mg/kg for twenty days. Finally, the histological morphology of the ovaries and sex hormone levels in the experimental groups were examined. Results: Our experiments showed changes in the oocyte stages, progressing to the cortical and vitellogenesis stages in the treated groups. Additionally, sex hormone levels increased in the groups exposed to that of propranolol and prazosin compared to the controls. The gonadosomatic index (GSI) exhibited a trend similar to the hormonal changes. The weight and length of the fish remained unchanged across the different groups. Conclusion: Our findings indicated that propranolol and prazosin, at the mentioned doses and treatment duration, had a positive effect on the sexual function of female three-spot gourami. [ABSTRACT FROM AUTHOR]

Copyright of Marine Fisheries: Jurnal Teknologi & Manajemen Perikanan Laut is the property of IPB University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Aeromonas hydrophila causes motile Aeromonas septicemia (MAS), a disease with a high mortality rate in tilapia culture. Feed-based vaccines with the incorporation of inactivated whole-cell bacteria into the feed offer promising tools to control MAS. Currently, the incorporation of genome-free bacteria as bacterial vaccine through the implementation of SimCells® technology into the feed has become a particular interest. Background/Objectives: This study investigates the efficacy of a feed-based vaccine incorporating genome-free A. hydrophila (FBV-GFAH) against MAS infection in red tilapia. Methods: The vaccine was prepared and delivered at 5% fish body weight for three consecutive days in weeks 0 (prime vaccination) and 2 (first booster vaccination), orally. Throughout a five-week experimental period, the immune-related genes (IL-1β, MHC-II, CD4, IgT, and IgM) expression in the hindgut and head kidney of the fish was determined using RT-qPCR assay. Lysozyme (serum) and overall IgM (serum, gut lavage, and skin mucus) productions were also detected. Results: Fish vaccinated with FBV-GFAH showed a significant (p ≤ 0.05) improvement in relative percent survival compared with unvaccinated fish following bacterial challenge. FBV-GFAH induced the expression of immune-related genes in the hindgut and head kidney, especially after booster vaccination. Furthermore, serum lysozyme activity and overall IgM production in serum, skin mucus, and gut lavage were also significantly (p ≤ 0.05) improved in the FBV-GFAH vaccinated fish than the unvaccinated fish. Conclusions: This study showed that FBV-GFAH is a promising feed-based vaccine technology to control MAS in cultured tilapia. [ABSTRACT FROM AUTHOR]

Microplastics are emerging pollutants of global concern, and their presence in the aquatic environment poses a serious risk for aquatic biota. While many studies have been conducted on the presence of microplastics in marine habitats, little research has been done in freshwater African reservoirs on microplastic pollution and their impacts on fish within the subtropical regions. To bridge this gap, the current study investigated microplastic abundances and distribution in freshwater fish within Nandoni reservoir, South Africa, across two seasons (i.e., hot–wet, cool–dry). Fish were randomly sampled using seine and gill nets from seven sites within the reservoir. In the laboratory, fish were then sorted according to taxa before dissecting them to remove the gills and the gastrointestinal tract (GIT). The organs were digested using hot hydrochloric acid and hydrogen peroxide, and the microplastics were classified according to their colours and shapes. Among the 94 fishes (i.e., 8 species) examined, microplastics were detected in 86.6% of the eight species caught. Microplastics were dominant in the gills and GIT during the cool–dry and hot–wet seasons, respectively. High microplastic abundances were found in the gills of Micropterus salmoides and the GIT of Coptodon rendalli, where fibres and the transparent colour were the most dominant. The results further showed high microplastic abundances in benthopelagic feeders highlighting that habitat influences fish consumption of microplastics whether directly or indirectly. Significant differences were observed in the feeding zone and season for all microplastic types. Microplastic sources in the reservoirs could be due to anthropogenic activities such as illegal dumping, fishing, and agriculture. Thus, there is a need for further investigation into the relation of fish weight, fish sex and body in relation to microplastic pollution. The highlighted ecological factors should be taken into consideration for future research and management actions aimed at mitigating and protecting the negative impacts of microplastic pollution on environmental and human health. [ABSTRACT FROM AUTHOR]

Simple Summary: Glycerol monolaurate, known for its strong antimicrobial properties, is a chemical compound formed by the combination of lauric acid and glycerol. This research focused on how glycerol monolaurate affects the growth, digestive enzyme activity, immune system, blood antioxidant level, and intestinal structure of black sea bream. This research could contribute to raising healthier aquatic animals, potentially reducing both the costs and environmental impact associated with aquaculture. These findings suggest that glycerol monolaurate may be the most suitable dietary supplement for fish; however, further research on its effect on the gut microbiota and gene expression is still required. An eight-week feeding trial was conducted to examine the impact of dietary supplementation with glycerol monolaurate (GML) on juvenile black sea bream. A basal diet was formulated containing 24% fish meal, while five additional diets were prepared, each supplemented with varying levels of GML: GML1 (0.01%), GML2 (0.02%), GML3 (0.04%), GML4 (0.08%), and GML5 (0.16%). Triplicate tanks were randomly allocated to each diet, each containing 20 fish with an initial weight of 1.55 ± 0.05 g. By the trial's end, the GML3 group displayed a notably higher final body weight (FBW), weight gain (WG), specific growth rate (SGR), and protein efficiency ratio (PER) compared to the other groups (p < 0.05), but the FCR was significantly higher in the control group. However, no significant differences were observed in the MFI, PPV, CF, HSI, IPF, VSI, or SR among the groups (p > 0.05). Regarding the proximate compositions of the dorsal muscle and whole body, no substantial differences were observed across the groups (p > 0.05). Additionally, there were no significant variations in digestive enzyme activity (p > 0.05), serum immune, or biochemical parameters in the midgut and hindgut among the treatment groups. But in the serum immune response IgM, C3 and C4 were significantly higher in the GML3 group as compared to the other groups (p < 0.05). However, the GML3 group exhibited significantly greater fore-intestinal villus height, crypt depth, villus height per crypt depth, and the number of goblet cells per villus compared to the other groups (p < 0.05). Overall, GML supplementation, particularly GML3, significantly improved growth indicators like the final body weight and intestinal morphology. While certain parameters remained unaffected, these findings suggest GML's potential as a beneficial dietary supplement in fish diets. [ABSTRACT FROM AUTHOR]

Purpose. Substantiation of the prospects for replacing fish meal in the composition of carp feeds with black soldier fly meal (Hermetia illucens) based on the analysis of studies of productive and individual functional parameters of the body of experimental groups of fish. Methodology. The first stage of the study lasted 30 days and was conducted in laboratory conditions at the Institute of Fisheries of the NAAS: a control and three experimental groups of age-1+ carp were formed, which were reared under identical optimal conditions. The control group of fish received a basic diet; in Experiment 1 black soldier fly meal was added to the feed to replace 100% of soybean meal, in Experiment 2 – to replace 100% of fish meal, in Experiment 3 – to replace 50% of fish meal. The second stage lasted 20 days and was conducted at the Lviv Experimental Station of the Institute of Fisheries of the NAAS in net cages placed in ponds. The control group of age-1+ carp was fed feed without supplements, while the experimental group was fed with black soldier fly meal to replace 100% of fish meal. During the study, the state of the main physicochemical parameters of the rearing environment was monitored. The results were analyzed using methods generally accepted in fish farming. The productive, morphological, hematological and antioxidant parameters of the fish body of experimental and control groups were determined. Findings. During both stages of the study, the temperature, oxygen, and hydrochemical conditions did not differ significantly between the experimental and control variants and met fish farming standards. Laboratory studies of fish sizes and weights showed the highest results compared to the Control were obtained in Experiment 3: body length to height ratio (l/H) – 2.64, body length to girth ratio (l/G) – 1.20, relative weight gain (RWG) – 18.5% against 16.1% in Control. In the carp muscles of all experimental groups, SOD activity was lower compared to the Control with a significant decrease of 49% in Experiments 1 and 2 (p < 0.001), in the hepatopancreas the difference was insignificant. Catalase activity in the hepatopancreas was higher in all experimental groups relative to the control group with the highest value in Experiment 2 (p < 0.01). Reverse trends were found for the content of LPO products (diene conjugates and TBC products) in muscles and hepatopancreas. In general, no significant changes in the activity of the antioxidant protection system were found in the investigated tissues; however, the obtained patterns require additional study for an objective assessment. Studies in cages showed that after complete replacement of fish meal with black lionfish meal in carp feeding, the weight of fish caught was 6.9% lower than in the Control. At the same time, a tendency for an increase in hemoglobin content and the count of erythrocytes in the blood of the experimental group compared to the control group was recorded. Originality. For the first time, the effectiveness of full or partial replacement of fish meal in carp feeds with black soldier fly meal was investigated according to a comprehensive analysis of productive, individual physiological and biochemical parameters of the fish body in the experimental groups. Practical value. The results of the study will allow determining the effectiveness and evaluating the potential of using insect protein in carp feeding on the example of black soldier fly meal. The application of the knowledge gained in fish farming practice will provide an opportunity to replace traditional feed components with an alternative cheap, affordable and environmentally friendly source of animal protein. [ABSTRACT FROM AUTHOR]

The effect of different feed rations on RAS-based pikeperch juveniles' growth parameters was studied. Juvenile pikeperch were reared in three separate experiments (I, II, and III) at a temperature of 24 °C with initial body weights of the fish at 1.3, 9.4, and 25.6 g, respectively. Four applied feed rations increased by 0.5% in each experiment: 3.0, 3.5, 4.0, and 4.5% of body weight per day (BW day−1) in experiment I; 2.0, 2.5, 3.0, and 3.5% BW day−1 in experiment II; 1.0, 1.5, 2.0, and 2.5% BW day−1 in experiment III. Each experiment in triplicates lasted 28 days. The fish were reared in tanks with working volumes of 1.0 m3 each. All experiments were performed in the same recirculating aquaculture system. The stocking density in experiments I, II, and III was 800, 400, and 200 individuals per tank, respectively. The results of experiment I showed the highest specific growth rate (SGR), weight gain (WG), and biomass gain at the feed ration of 4.5% BW day−1 (P < 0.05). In experiment II, feed ration from 2.5 to 3.5% BW day−1 showed the highest final weight (P < 0.05). In experimental III, feed ration of 2.0 and 2.5% BW day−1 showed the highest final weight, SGR, and WG (P < 0.05). Only in experiment III, based on SGR and WG, second-order polynomial regression showed that the optimal feed ration for pikeperch was 2.35–2.39% BW day−1. [ABSTRACT FROM AUTHOR]

The present study aimed to isolate vibrio species from fresh and marine water fish responsible for summer mortality syndrome affecting Cage- cultured grouper species fish (Epinephelus aneus; Epinephelus guaza; Epinephelus alexandrines and Epinephelus caninus) and Lout fish (Argyrosomus regius) farms in Egypt. A total of 250 fish of each species of grouper species fish (E.aneus; E.guaza; E.alexandrines and E.caninus) and Lout fish (Argyrosomus regius) were collected at different times. The fish samples were collected at summer and autumn seasons. The fish samples were 25 from each species in each season. Clinically diseased fish were collected live then rinsed with sterile water and packed in a sterile polystyrene bag. Collected samples were immediately transported in an icebox to the private fish diseases Lab, Alexandria branch. Grouper fish weight between (500 - 1000) g and Lout fish weight (4 - 4.5) Kg. The collected fish samples were submitted directly to the lab for clinical and bacteriological examination. The results cleared that, after the clonical signs, post-mortem examination, isolation and identification on different media and molecular identification (PCR) of the isolated bacteria the main bacteria isolated from Grouper and lout were V. alginolyticus and V. parahaemolyticus. This study concluded that, the Multi stress factors are responsible for summer mortality syndrome affecting cultured grouper species fish (Epinephelus aneus; Epinephelus guaza; Epinephelus alexandrines and Epinephelus caninus) and Lout fish (Argyrosomus regius) in Egypt; thermal stress associated with heatwaves is the main predisposing factor. Co-infections are very common in nature and occur when Cagecultured grouper species fish (E.aneus; E.guaza; E.alexandrines and E.caninus) and Lout fish (A. regius) are infected by two or more different pathogens either by simultaneous or secondary infections. [ABSTRACT FROM AUTHOR]

Tracking of animal migrations using telemetry technologies needs to take into consideration the burden that the tag exerts on the animal. Here, we examined the potential impacts of acoustic tags of two sizes (nominally a 'V6' [smaller] and 'V7' [larger]) on the downstream riverine migration success and behaviour of wild Atlantic salmon (Salmo salar L.) smolts. One hundred fish were tagged with either a V6 or V7 tag. Tag burden (tag: fish weight) ranged from 1.88% to 7.39% and differed significantly between fish tagged with the V6 (mean [SD] = 3.63% [0.51%]) and the V7 tags (mean [SD] = 5.84% [0.95%]). There was no significant difference in the in‐river migration failure between the two groups when tested with a time‐to‐event analysis. There were also no differences in other elements of the migratory behaviour (rate of movement, time of detection and residency time) between the two tagging groups. These data support the use of acoustic tracking for monitoring smolt migration and highlight that tagging of smaller smolts at up to 7.39% tag burden to gain a more representative understanding of migration success and behaviours across a smolt population. [ABSTRACT FROM AUTHOR]

In contemporary markets, fish are frequently wrapped in cling film, necessitating consumers' reliance on visual cues to assess freshness. This study explores whether common Japanese consumers can accurately discern fish freshness based solely on visual information. We conducted an online experiment with 529 randomly selected participants in Japan by asking them to select the freshest fish from photographs of horse mackerel with varying freshness levels. In order to elucidate the mechanism of freshness detection, we conducted principal component analysis on the quantified body color and shape data. Additionally, we measured physical characteristics such as lipid contents, gloss, length, and weight of the fish. This study examines the correlation between these visual cues and consumers' judgments, revealing the accuracy of visual indicators used by consumers in daily assessments of fish freshness. These findings suggest that a portion of Japanese consumers can correctly identify the freshness of fish based on appearance. They primarily rely on the brightness of the fish's eyes and specific color combinations of the body to judge freshness, with the shape of the fish having less impact. Comparing the selection frequency between high- and low-accuracy participants, we observed that a low accuracy in freshness detection was not solely due to a lack of sensitivity to signals from photographs, but may also result from a misinterpretation of these signals by consumers. [ABSTRACT FROM AUTHOR]

In recirculating aquaculture systems (RAS), off‐flavours accumulated in fish muscle tissue can be problematic in terms of consumer acceptance and the reputation of farmed fish products. Off‐flavours often give fish earthy, muddy, or other undesirable flavours. Typically, off‐flavours are removed during a depuration period in which fish are fasted and held in clean water. Unfortunately, this causes additional costs and delayed sales, while fish lose weight and show a decrease in lipid content. First, we studied fish growth in a partial RAS (PRAS) where the conditions are very similar to those in depuration with a water exchange rate of 4000 L kg−1 feed, compared to RAS with a 650‐L water kg−1 feed. Rainbow trout (Oncorhynchus mykiss) was reared in both systems. Our aim was to combine the benefits of a higher water exchange rate: the lack of need for biofilters and a lower accumulation of off‐flavours while obtaining stable rearing conditions. Additionally, we studied the effects of moderate feeding and H2O2 addition during depuration. The fish grew faster in a PRAS than in a RAS when fed ad libitum. Thirteen off‐flavour compounds were found in the fish flesh and 11 in the circulating water. The H2O2 addition led to decreased levels of off‐flavours in the tank water and in fish muscle. The results showed no significant differences in off‐flavours between the fed and not‐fed systems, showing that moderate feeding did not prevent a good depuration result. However, the lipid content and the overall fish weight were higher in the fed systems, which suggests more effective depuration. Increased depuration efficiency can be an important tool when considering ways to improve the profitability of production. [ABSTRACT FROM AUTHOR]

This study evaluated how feeding the common carp (Cyprinus carpio) at multiple protein levels affected their growth and body composition during the winter season. Four experimental diets with varying protein levels were tested, with protein levels of 30% (T1), 28% (T2), 26% (T3), and 35% (T4), respectively. Fish were obtained and kept in a water culture pond with dimensions of 4x4x3 meters. Fish average weight was 148.7± 5.76g, while its length measurements were recorded at 24.33± 2.45cm, fork length at 21.15± 2.34cm, and standard length at 18.96± 1.66cm. The fish were purchased from a hatchery farm in Mosul City, northern Iraq. For 90 days, the fish were fed experimental feed once daily until they reached satiation. Compared to other treatments, fish fed T2 (28% protein) showed higher daily weight gain, total weight gain, weight growth rate, relative growth rate, metabolic growth rate, and specific growth rate. The feed diet T2 had the highest Fulton and modified condition factor, reaching 4.84± 0.14; 2.81± 0.03, whereas the highest condition factor was recorded (3.34± 0.16; 2.1± 0.03) for feed treatment T3. Feeding indicators in the feed treatment T2, such as total feed intake, daily feed consumption, and total protein productivity, were greater. The protein efficiency ratios of the fish groups fed formulations T2, T1, and T3 were recorded at 1.32± 0.004, 1.34b± 0.004, and 1.425c± 0.007%, respectively. In comparison, a significant difference was detected for the fish group consuming feed T4, with a value of 1.058d± 0.009%. For the length-weight relationships, an isometric growth (26, 35%) was recorded for T3, an allometric positive growth for T2, and a negative growth for T1. [ABSTRACT FROM AUTHOR]

The roll damping coefficient is essential when considering the viscous effect in the potential-based hydrodynamic analysis of fishing vessels; it is an important factor in the roll motion response. The present study performs free roll decay simulations, altering weight variables using Computational Fluid Dynamics (CFD) to investigate the correlation between the roll damping coefficient and the weight variation of a fishing vessel. The time series of roll amplitude and roll damping coefficient are compared, for varying vertical and longitudinal centres of gravity and radii of gyration in roll motion. As the vertical centre of gravity increases, both the roll decay period and the roll damping coefficient also increase. The roll decay period tends to increase with the increase in the radius of gyration during roll motion, while the roll damping coefficient exhibits a decrease. A longitudinal centre of gravity has a limited effect on free roll decay characteristics. The roll damping coefficients between the maximum and minimum combinations of weight variables show significant differences. The findings of the present study could enhance the understanding of the safety of fishing vessels based on their loading conditions. Consequently, future research could further improve the results obtained in the present study by considering various hull shapes and speeds. [ABSTRACT FROM AUTHOR]

In this study, it was aimed to determine the length-length, length-weight relationships and condition factor values of the Uranoscopus scaber, which is distributed in the Cape Jason from the Central Black Sea. Within the scope of the study, a total of 112 fish individuals, 61 females and 51 males, caught using nets were examined. Standard length (SL), total length (TL) measurements and fish weights (W) of fish individuals were determined. Since statistical differences (t-test, P<0.05) were determined between the measurements of male and female individuals, evaluations were carried out separately for females, males and all individuals. The length-weight relationship equations and correlation coefficients of female, male and all U. scaber individuals are W=0.0099TL3.220 (r²=0.963), W=0.0239TL2.876 (r²=0.953), and W=0.0142TL3.079 (r²=0.956) respectively. It was determined that female individuals of the U. scaber showed a positive allometric growth in this habitat, while male individuals showed a negative allometric growth. Total length-standard lengtht relationship equations and correlation coefficients of female, male and all individuals of U. scaber are TL=1.2009SL+0.81 (r²=0.992), TL=1.267SL+0.0903 (r²=0.992), and TL=1.2269SL+0.5198 (r²=0.992), respectively. The average condition factor values of female, male and all U. scaber individuals were calculated as 1.7979±0.0255, 1.7340±0.0257, and 1.7688±0.0183, respectively. The determined parameters are the first data for the Cape Jason population of U. scaber in the Central Black Sea. [ABSTRACT FROM AUTHOR]

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Salmonids, specifically Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss), are commonly farmed and their gut microbiota plays important roles for optimal growth, health, and physiology. However, differences in experimental design, technical factors and bioinformatics make it challenging to compare the results from different studies and draw general conclusions about their influence on the fish gut microbiota. For a more comprehensive understanding of the gut microbiota, we collected all the publicly accessible 16S rRNA gene sequencing data with clearly stated sample metadata from freshwater Atlantic salmon and rainbow trout intestinal contents and mucosa sequenced on the Illumina MiSeq platform. A total of 783 samples from 19 published studies were included in this meta‐analysis to test the impact of the technical, environmental, and host‐accociated factors. This meta‐analysis revealed that all the tested factors significantly influenced the alpha and beta diversities of the gut microbiota of salmon and trout. Technical factors, especially target region and DNA extraction kit, affected the beta diversity to a larger extent, while host‐associated and environmental factors, especially diet and initial fish weight, had a higher impact on the alpha diversity. Salmon had a higher alpha diversity and higher abundance of Enterococcus and Staphylococcus than trout, which had higher abundance of Weissella and Mycoplasma. The results of this meta‐analysis fill in a critical knowledge gap that demonstrate technical methodologies must be standardized and factors associated with host and environment need to be accounted for in the future design of salmonid gut microbiota experiments. [ABSTRACT FROM AUTHOR]

Plastic pollution is a global problem affecting all ecosystems, and it represents most of the marine litter. Offshore aquaculture is a sector particularly vulnerable to this issue. To investigate this concern, the present study employed videography to monitor macroplastics at an offshore fish farm on Madeira Island (Portugal) and analysis of fish gut content to evaluate macroplastic ingestion by farmed sea bream Sparus aurata. Our analysis revealed that the majority of identified plastic debris originated from domestic use (66.66%) and fisheries/aquaculture activities (24.99%). While the number of dead fish suitable for sampling was limited (1.05% of the total mortality), macroplastic debris ingestion was identified in 5.15% of the total mortalities and reported for the first time in species in offshore farming conditions. Fish ingested fragmented plastic sheets, with the amount positively correlated with fish weight (r = 0.621, p = 0.031, n = 12). Notably, the stretched length of these fragments exceeded 50% of the standard length of most fish. Inconsistencies were observed in the number of samples collected per cage and per week. To ensure robust results, these discrepancies should be rectified in future studies. Additionally, extending the sampling period to encompass all seasons would be beneficial for a more comprehensive understanding of seasonal variations in plastic occurrence. [ABSTRACT FROM AUTHOR]

Monitoring and evaluating fish growth and health relies on accurate aquaculture body size and weight data. Pearl's gentian grouper has tender flesh and rapid growth, and the scale of aquaculture is increasing yearly. Moreover, it is inefficient to measure body size and weight data manually regularly, so in this paper, taking pearl gentian grouper as the research object, we propose a body size and weight estimation method based on machine vision and improve DeepLabV3 + algorithm, with the MIoU reaching 97.37% on the self-constructed dataset, to extract the closed contour of the fish body curve, then apply the algorithm for measuring body scale traits. This paper determines the critical points of body scale calculation. It uses the calibration coefficients to calculate the body scale parameters and then estimate fish body weight. In the established body weight estimation model, the coefficient of determination of the CatBoost regression model based on the total length, body height, body thickness, and area of the fish was R2 of 0.987 which realized the high-precision estimation of the body weight of the pearl gentian grouper and provided the basis for intelligent grading. [ABSTRACT FROM AUTHOR]

Soybean meal and its processing products have been widely used in fish feeds. In aquaculture, there is a lack of effective targeted protection against food-borne enteritis caused by feeding soybean meal. Our preliminary research found that Indole-3-butyric acid (IBA) has the potential application value. The present research evaluated the influence of supplementing different levels of IBA to diets containing high soybean meal on juvenile pearl gentian grouper (Epinephelus fuscoguttatus♀ × E. lanceolatus♂). The feeding experiment lasted for eight weeks and the initial weight of the fish was 21.17 ± 0.02 g. The FM diet with fish meal as the main protein source was prepared. In addition, six diets were prepared in which soybean meal was used to replace some of the fish meal as a secondary protein source. IBA was added to these six diets at 0 g/kg, 0.8 g/kg, 1.6 g/kg, 2.4 g/kg, 3.2 g/kg, and 4.0 g/kg respectively. The growth performance of the 2.4 g/kg IBA-added group was significantly higher than that of the non-added group (P < 0.05); the group with IBA additions equal to or more than 2.4 g/kg had longer intestinal folds and more absorptive cells; the levels of ACP, LYS, C3, and C4 in the gut showed a significant quadratic trend of decreasing and then increasing with the increase of IBA and reached a minimum at 2.4 g/kg (P < 0.05); the gene expression of cytokines il1β, il17, tnfα, il4, il5, and tgfβ1 varied significantly among the groups with different IBA additions (P < 0.05). In addition, this study investigated the role of feeding 2.4 g/kg IBA on fish from the perspective of intestinal flora. In this study, we concluded that 2.4 g/kg IBA could be added to diets using soybean meal replacing 40% of fish meal, which had beneficial effects on growth performance, intestinal inflammation alleviation and intestinal flora homeostasis. This provides a theoretical basis for IBA to mitigate SBMIE in pearl gentian grouper and promote the further application of soybean meal in carnivorous fish. [ABSTRACT FROM AUTHOR]

Iron (Fe) is a crucial mineral for the health of fish. The investigation explored the effects of two different sources of iron (organic and inorganic) and two levels (60 and 85 mg/kg) of Fe on the innate immunity, antioxidant capacity, and hematological responses of Nile tilapia. Fish with an average weight of 16.57 ± 2.25 g were fed three times a day for a duration of seven weeks. A total of 400 fish were distributed among 20 tanks, each with a capacity of 240 L and housing 20 fish. The experiment comprised five treatments, and the experimental design employed was a completely randomized design, which included the following treatments: a basal diet (BD) with no addition of Fe in the premix, 60 mg/kg Inorganic Fe, 60 mg/kg Organic Fe, 85 mg/kg Inorganic Fe, and 85 mg/kg Organic Fe. The results indicated that the use of organic Fe significantly improved the hematocrit levels and mean corpuscular hemoglobin. Conversely, the values of lysozyme decreased in fish that were fed with the organic Fe source. However, the hemolytic activity of the complement system and the production of the superoxide anion test exhibited an increase with the use of organic Fe. Furthermore, the fish that were fed with the 85 mg/kg organic diet demonstrated superior antioxidant responses. In conclusion, the inclusion of organic Fe at a concentration of 85 mg/kg was found to be more efficient for the growth of juvenile Nile tilapia. [ABSTRACT FROM AUTHOR]

Nile Tilapia (Oreochromis niloticus) management procedures are directly linked to the final quality of the product. The aim of this study was to evaluate the effect of pre-slaughter density and different stunning methods on biochemical, respiratory and muscle injury parameters associated with quality and sensory characteristics of Nile tilapia fillets. Fish with an average weight of 762±105 g were used, first collected called the control group. The experiment was conducted in a 2 × 2 factorial scheme, with two densities (50 and 300 kg of live weight m−3) and two stunning methods thus totaling four treatments, with 15 repetitions per treatment totaling 75 fish sampled. Blood gas analysis, evaluation of biochemical parameters, analysis of meat quality and sensory analysis were carried out. For blood gas, biochemical and enzymatic parameters, the highest values were obtained for the density of 300 kg m−3 and asphyxia method: partial pressures of CO2; glucose and lactate, the highest values presented were 268.98 and 11.33 mg dL−1 respectively. As well as enzymatic activities, Creatinine kinase (CPK); Creatinine kinase isoenzyme (CKMB) showed higher values (768.93 and 1078.98 mg dL−1 respectively) in the higher density and asphyxia method. Conversely, when evaluating the quality parameters, the highest values were observed for lower density and thermonarcosis. High depuration density (300 kg m−3), combined with the asphyxiation stunning method, promotes changes in respiratory dynamics and provides greater stress, less firm fillet texture and greater weight loss due to cooking, as well as changes in creatine kinase (CK) and its CK-MB isoenzyme, demonstrating greater muscle damage. On the other hand, the density of 50 kg m−3 during pre-slaughter, combined with the method of stunning by thermonarcosis, provide a longer period of permanence in pre rigor mortis, which will result in fillets with a better sensory profile. [ABSTRACT FROM AUTHOR]

The interplay between environmental, biological, and physical factors often leads to the deterioration of dead fish in marine cages prior to their removal. Depending on the weight of the dead fish and the frequency of their removal, deterioration can progress to a stage where visual identification by divers becomes challenging, thereby disrupting accurate counting of dead fish. This study presents a practical precision tool for monitoring the number of dead fish during the pregrowth and growth phases of caged European sea bass (Dicentrarchus labrax). To improve the assessment of collected mortality, experiments were conducted in farming cages with various fish weights. Identifiable fish rates (I, %) were calculated every 24 hr and classified into four weight classes: WC1 (4–15 g), WC2 (15–30 g), WC3 (30–80 g), and WC4 (>80 g). The corrected number of dead fish (M) was calculated by dividing the collected number (C) by a correction factor (McR), which was determined based on the adopted removal frequency. The possible mortality removal frequencies per week (Fn) included operations such as F7 (daily), F3 (3 times), F2 (2 times), and F1 (once). The smallest correction denominator was 22% for WC1 at a frequency of once per week, whereas the maximum was 100% for WC3 and WC4 daily. The results revealed a high negative significant correlation between Fn and uncollected degraded fish rate (UR) (r = –0.841, p < 0.05). Applying corrections to mortality collected in three finished batches (B2, B3, and B7) led to an increase in the mortality rate by 3.9% ± 1.5%, 5.5% ± 0.7%, and 5.0% ± 0.5%, respectively. This explained 16.8% ± 4.7%, 65.5% ± 26.7%, and 30.3% ± 3.7% of fish disappearances in B2, B3, and B7, respectively. The significance of this study lies in its practical applicability to fish farms as a precise tool for monitoring fish raised in marine cages. [ABSTRACT FROM AUTHOR]

This study aims to identify the characteristics of skin, bones, and scales as a biomaterial byproduct of snakehead fish, Channa striata (Bloch, 1793) before and after the extraction process into gelatin, based on 36 fresh snakehead fish samples. The biomaterials were identified, including their proximate composition (by weight of protein, fat, moisture, ash) collagen, amino acids. The physicochemical properties of gelatin in terms of yield, gel strength, viscosity pH, and functional groups were determined for scales, skin and bones. Combined, these biomaterials made up about 47.74 % of the total byproduct by weight of snakehead fish that would usually be discarded. Moisture and protein content of the skin was higher than that of scales and bone (P < 0.05), and fat content was higher in bone than in skin and scales (P < 0.05). The lowest ash content was in skin (<1 %), compared to scales and bone (P < 0.05). The collagen content of scales was higher than that of skin and bone (P < 0.05). Glycine and proline in the three biomaterials were nearly equal and highest in skin, scale, and bone, respectively. There were significant differences in viscosity and gel strength of the three types of gelatin (P < 0.05), the highest viscosity was in skin gelatin while the best gel strength was in scale gelatin, while pH was not significantly different (P > 0.05). The application of the same method and solvent can produce different properties and characteristics of gelatin, and the presence of functional groups helps determine the occurrence of changes in the secondary structure of gelatin from the three biomaterials. [ABSTRACT FROM AUTHOR]

Chaunax abei Le Danois, 1978, is a bottom-dwelling species caught by bottom trawls in Suruga Bay. In the present study, we assessed the age and growth pattern of C. abei from Suruga Bay during the period of 2021-2022 for the first time. The total length (TL) of the population ranged from 37.4-268.8 mm (mean ± SD: 124.7 ± 3.64 mm), and the fish weight (W) between 1.11-491.75 g (mean ± SD: 58.40 ± 7.25 g). The length-weight relationship was estimated as 𝑊𝑊 = (2.07 × 10-5)𝑇𝑇𝑇𝑇2.996 (r² = 0.937). Age determination was based on annual growth ring counts of transverse sections of the sagittal otoliths and age ranged from 1 to 12 years, with the majority of fish aged 4 (32.79 %) years old. The von Bertalanffy growth function was used to model the growth, and the parameters were found as: TL∞ = 468.1 mm, K = 0.056 year-1, t0 = -0.402 year. This research provides the first results on the growth of C. abei and enriches the regional fisheries biology database. Furthermore, it presents the primary population data on the growth patterns of one of the chaunacid species. [ABSTRACT FROM AUTHOR]

The aim of this study was to assess the occurrence of microplastic in digestive organs (esophagus to intestine) of popular marine commercial fish species: Jack (Caranx SP.), blackspot snapper (Lutjanus fulviflamma), coral grouper (Epinephelus carallicala), golden snapper (Lutjanus johnii) and pickhandle barracuda (Sphyraena jello) from Pangempang Estuary in Indonesia. To separate the microplastic particles, each sample was digested using alkaline digestion solution, filtered on Whatman paper and then dried. Microplastic particles in the processed digestive organ contents were identified and enumerated using a dissecting stereo microscope. Microplastics were observed in 94 % of fish digestive organs sampled: 100 % jacks (n = 10), 80 % blackspot snapper (n = 10), 100 % coral grouper (n = 10), 90 % golden snapper (n = 10) and 100 % pickhandle barracuda (n = 10). In these fish samples we found in average of 41 ± 6.0, 26 ± 11.0, 15 ± 2.0, 11 ± 1.0 and 14 ± 2.0 SE microplastic particles per individual and an average of 499.5 ± 94.4, 501.5 ± 198.8, 83.6 ± 18.4, 79.8 ± 11.6 and 40.2 ± 25.0 SE microplastic particles per kg fish weight, in jacks, blackspot snapper, coral grouper, golden snapper and pickhandle barracuda, respectively. Fiber was the most dominant type accounting for 78.6 % of all observed microplastics. Microplastic beads were not detected. The correlation of the average consumed microplastic and the average fish weight per species showed a negative relationship (R² = 0.36), but was not significant (p-value = 0.28). Our finding suggests that demersal fish like jacks, blackspot snapper and coral grouper may have ingested a higher quantity of microplastic particles compared to pelagic species like pickhandle barracuda. [ABSTRACT FROM AUTHOR]

The study examined Xenentodon cancila (Hamilton) breeding biology, reproduction, and larval rearing. In this study, gonadosomatic index (GSI) and fecundity were measured for breeding biology every 15 days. Nine doses of common carp pituitary gland (CPG), human chorionic gonadotropin (HCG), and Ovaprim for breeding were administered, except in the control treatment that was without hormones. Mustard oil cake (D1), powdered feed (D2), and one-day-old live tilapia (Oreochromis sp.) larvae (D3) were used to determine larval survival after 28 days. From the end of May to mid-July, the mean GSI value exceeded 15 ± 0.72%, peaking at 16.02 ± 1.28% in June. Mean fecundity ranged from 110 ± 13.34 to 2961 ± 318.57, peaking at the end of June 2019, which indicated that this was the peak breeding season for X. cancila. The best spawning was with CPG at 20 mg kg−1 fish body weight (BW) and Ovaprim at 1.0 ml kg−1 BW, but the control group (B) and the group administered 500 IU kg-1 HCG (H1) did not spawn. Latency and hatching periods were 19-21 and 260-288 h, respectively. The highest fertilization, hatching, and survival rates were 92 ± 4.63%, 69 ± 5.52%, and 66 ± 4.11% with 20 mg kg−1 CPG (C2), while the next closest value was recorded with 1.0 ml kg−1 Ovaprim (O2). After 28 days, D3 had the highest survival rate (47.5 ± 4.62%), followed by D2 (31 ± 2.42%), and D1 (18 ± 1.54%). The findings will be useful for hatcheries, fish farmers, the ornamental fish sector, and biodiversity protection. [ABSTRACT FROM AUTHOR]