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Purpose. To characterize the productive and biological features of juvenile tench (Tinca tinca Linnaeus, 1758) grown in a recirculation aquaculture system and to select the optimal stocking density for intensive cultivation technology. Methodology. The studuy was conducted at the incubation workshop of “Karpatskyi Vodogray” LLC using a recirculation aquaculture system. Two 0.96 m3 tanks were used for the study.The material for thestudy were tench juveniles obtained in hatchery conditions. The cultivation of young-of-the-year was carried out in two stages: cultivation for 28 days at stocking densities of 100 and 75 thousand ind./m3, with the repeatability for two years (Experiment I – 2021, Experiment II – 2022). Over the next 94 days, at stocking densities of 15 and 20 thousand ind./m3 (Experiment I – 2021) and 10 and 15 thousand ind./m3 (Experiment II – 2022). The data obtained as a result of the experiments was subjected to statistical processing in MS Excel 2016. The criteria for analyzing were their average value and standard error (M±m). Findings. The study showed that when growing young-of-the-years in a recirculation aquaculture system, the most optimal stocking density at the first stage of cultivation was 100 thousand ind./m3.Reducing the stocking density to 75 thousand ind./m3 allowed increasing the survival rate of larvae by 2.0–2.5%, however, there was no clear effect on their growth rate. At the second stage, at a stocking density of tench juveniles of 10–20 thousand ind./m3, similar productive and biological parameters of young-of-the-years were obtained, while their yield from 1 m3 of pools ranged from 3.52 to 6.67 thousand ind./m3. Thus, at a larval stocking density of 15 thousand ind./m3, 4.86–5.13 thousand ind./m3 of young-of-the-year fish were obtained with an average weight of 5.1–7.6 g, with a survival rate of 78.0–82.1%, which ensured a fish production yield of 24.86 to 39.00 kg/m3. With a decrease in stocking density to 10 thousand ind./m3, the survival rate and body weight of young-of-the-years increased by 4.5% and 1.45 times, respectively, but the yield of young-of-the-years was only 3.52 thousand ind./m3. Originality. For the first time in Ukraine, a comprehensive assessment of the growth of juvenile tench in conditions of a recirculation aquaculture system at different stocking densities for the main technological stages of cultivation was carried out. Practical Value. The results obtained allow us to demonstrate the effectiveness of applying new technologies for growing non-traditional objects in order to increase the economic performance of Ukrainian fish farming, and their comprehensive analysis will allow us to develop the main elements of the technology for growing tench in intensive aquaculture conditions.

Purpose. To characterize the productive and biological features of juvenile tench (Tinca tinca Linnaeus, 1758) grown in a recirculation aquaculture system and to select the optimal stocking density for intensive cultivation technology. Methodology. The studuy was conducted at the incubation workshop of “Karpatskyi Vodogray” LLC using a recirculation aquaculture system. Two 0.96 m³ tanks were used for the study. The material for thestudy were tench juveniles obtained in hatchery conditions. The cultivation of young-of-the-year was carried out in two stages: cultivation for 28 days at stocking densities of 100 and 75 thousand ind./m³, with the repeatability for two years (Experiment I – 2021, Experiment II – 2022). Over the next 94 days, at stocking densities of 15 and 20 thousand ind./m³ (Experiment I – 2021) and 10 and 15 thousand ind./m³ (Experiment II – 2022). The data obtained as a result of the experiments was subjected to statistical processing in MS Excel 2016. The criteria for analyzing were their average value and standard error (M±m). Findings. The study showed that when growing young-of-the-years in a recirculation aquaculture system, the most optimal stocking density at the first stage of cultivation was 100 thousand ind./m³ . Reducing the stocking density to 75 thousand ind./m³ allowed increasing the survival rate of larvae by 2.0–2.5%, however, there was no clear effect on their growth rate. At the second stage, at a stocking density of tench juveniles of 10–20 thousand ind./m³, similar productive and biological parameters of young-ofthe-years were obtained, while their yield from 1 m³ of pools ranged from 3.52 to 6.67 thousand ind./m³ . Thus, at a larval stocking density of 15 thousand ind./m³, 4.86–5.13 thousand ind./m³ of young-of-the-year fish were obtained with an average weight of 5.1–7.6 g, with a survival rate of 78.0–82.1%, which ensured a fish production yield of 24.86 to 39.00 kg/m³ . With a decrease in stocking density to 10 thousand ind./m³, the survival rate and body weight of young-of-the-years increased by 4.5% and 1.45 times, respectively, but the yield of young-of-the-years was only 3.52 thousand ind./m³. Originality. For the first time in Ukraine, a comprehensive assessment of the growth of juvenile tench in conditions of a recirculation aquaculture system at different stocking densities for the main technological stages of cultivation was carried out. Practical Value. The results obtained allow us to demonstrate the effectiveness of applying new technologies for growing non-traditional objects in order to increase the economic performance of Ukrainian fish farming, and their comprehensive analysis will allow us to develop the main elements of the technology for growing tench in intensive aquaculture conditions. [ABSTRACT FROM AUTHOR]

Discharges to the aquatic environment of pharmaceuticals represent a hazard to the aquatic organisms. Subchronic assay with 17‐alpha‐ethinylestradiol (EE2) and in vitro essays with pharmaceuticals of environmental concern were conducted to examine the sensitivity of tissue acetylcholinesterase (AChE) and carboxylesterase (CbE) activities of Tinca tinca to them. Subchronic exposure to 17‐alpha‐EE2 caused significant effects on brain, liver, and muscle CbE, but no on AChE activities. Most of the pharmaceuticals tested in vitro were considered as weak inhibitors of tissular AChE activity. Depending on the tissues, some compounds were classified as moderate inhibitors of CbE activity while other were categorized as weak enzymatic inhibitors. An opposite trend was observed depending on the tissue, while brain and liver CbE activities were inhibited, the muscle CbE activity was induced. Changes experienced on enzymatic activities after exposure to pharmaceuticals might affect the physiological functions in which these enzymes are involved. In vitro exposure to 17‐alpha‐EE2 in tench could be an informative, but not a surrogate model to know the effect of this synthetic estrogen on AChE and CbE activities. [ABSTRACT FROM AUTHOR]

Purpose. Tench (Tinca tinca)is a popular species of cyprinids that lives in our waters. It has small scales that are firmly embedded in the mucous membrane of the skin. This is one of the few European fish that has sexual dimorphism. Tench is found in almost all regions of Europe, except the northern part of Great Britain, Iceland and the northern part of the Scandinavian countries. Interestingly, this species can be found in waters with low salinity, especially in the Baltic Sea, in its coastal zone. This species easily survives in waters with low oxygen content. As a rule, it prefers standing or, at best, poorly flowing waters. The ideal conditions for tench are shallow waters with warm water and developed vegetation. In deeper lakes, it lives in the coastal zone. Its meat is considered valuable. High economic importance and low production of tench in aquaculture in recent years has led to the development of scientific activities aimed at determining the most optimal possible production parameters of this species. Findings. The author of the work reviewed and analyzed professional scientific literature sources, manuals and textbooks of domestic and foreign authors on the cultivation of tench as an object of non-traditional aquaculture. In particular, the historical aspects of tench cultivation, its biological characteristics and features of breeding are considered. Practical value. The review of literature sources can be useful for the preparation of lecture material during the training process for specialists in specialty 207 “Aquatic Bioresources and Aquaculture”, including specialists in ichthyology, veterinary medicine, zoology.

Fishery residues are abundant raw materials that also provide numerous metabolites with high added value. Their classic valorization includes energy recovery, composting, animal feed, and direct deposits in landfills or oceans along with the environmental impacts that this entails. However, through extraction processes, they can be transformed into new compounds with high added value, offering a more sustainable solution. The aim of this study was to optimize the extraction process of chitosan and fish gelatin from fishery waste and their revalorization as active biopolymers. We successfully optimized the chitosan extraction process, achieving a yield of 20.45% and a deacetylation degree of 69.25%. For the fish gelatin extraction process, yields of 11.82% for the skin and 2.31% for the bone residues were achieved. In addition, it was demonstrated that simple purification steps using activated carbon improve the gelatin's quality significantly. Finally, biopolymers based on fish gelatin and chitosan showed excellent bactericidal capabilities against Escherichia coli and Listeria innocua. For this reason, these active biopolymers can stop or decrease bacterial growth in their potential food packaging applications. In view of the low technological transfer and the lack of information about the revalorization of fishery waste, this work offers extraction conditions with good yields that can be easily implemented in the existing industrial fabric, reducing costs and supporting the economic development of the fish processing sector and the creation of value from its waste. [ABSTRACT FROM AUTHOR]

During surveys on myxosporean parasites of Lake Balaton and River Danube fishes, two Thelohanellus spp. were found on tench (Tinca tinca) and on common nase (Chondrostoma nasus). They were identified as Thelohanellus pyriformis and Thelohanellus cf. fuhrmanni, respectively. Myxospores of T. pyriformis from tench were collected from arteria branchialis afferens of gill filaments. The mature myxospores of this species were pyriform in shape and 19 ± 0.6l (18–19.5) long, 8.2 ± 0.54 (7.5–9) wide, 7.3 ± 0.25 (7–7.5) thick containing polar tubules with 9–10 turns. The plasmodia of Thelohanellus cf. fuhrmanni were collected from under the skin of snout of the common nase. The myxospores were pyriform, 16.3 ± 0.39l (15.5–16.5) long, 6.5 ± 0.55 (6.3–7) wide, 6.3 ± 0.53 (5.8–7) thick containing polar tubules with 6 turns. Small subunit ribosomal DNA sequences of both Thelohanellus species differed from other known myxozoans. The myxospores morphology, histopathology and ssrDNA sequences supported a diagnosis of T. pyriformis from tench and T. cf. fuhrmanni from common nase.

In the wild, most animals experience daily fluctuations in threats and resources that are synchronised with environmental time cues such as the light-dark cycle. Consequently, animals have evolved daily behavioural patterns (i.e., diurnal or nocturnal) that enhance their fitness by, for example, reducing the temporal overlapping with predators. In fish, previous studies revealed stronger physiological stress responses during the resting period of the species. However, little is known about the circadian modulation of stress indicators and how they are influenced by daily behavioural patterns. In this research, we investigated the behavioural stress responses of two farmed fish species with different activity patterns: the diurnal Nile tilapia (Oreochromis niloticus) and the nocturnal tench (Tinca tinca). To this end, we examined the behavioural response of individuals exposed to the diving test every 4 h over a 24 h cycle (n = 12 fish/species/time point). Results indicated that most behavioural indicators varied according to the time of day, aligning with the daily rhythmic pattern of the two species. Tilapia exhibited stronger stress responses to novelty during the dark phase, while tench displayed higher stress during the light phase. This was supported by stress-related behaviours such as freezing and erratic movements (in both tilapia and tench) and bottom-dwelling (in tench only). These results indicated that stress responses peaked during the resting phase of each species, although behavioural indicators exhibiting this daily variation did not completely coincide between the studied species. Overall, these findings suggest interspecific differences in the daily modulation of behavioural stress indicators in farmed fish, an effect with potential relevance for welfare. Understanding the activity rhythmic patterns, resting periods, and associated daily variation in stress for each fish species of interest can precisely help tailor farming procedures to minimise suffering. • Behavioural stress indicators varied according to the time of day in both diurnal and nocturnal species. • Behavioural stress response was stronger during the resting phase of each species. • Behavioural stress indicators did not completely overlap between species. • Biological rhythms should be considered to improve fish welfare in captivity. [ABSTRACT FROM AUTHOR]

During surveys on myxosporean parasites of Lake Balaton and River Danube fishes, two Thelohanellus spp. were found on tench (Tinca tinca) and on common nase (Chondrostoma nasus). They were identified as Thelohanellus pyriformis and Thelohanellus cf. fuhrmanni , respectively. Myxospores of T. pyriformis from tench were collected from arteria branchialis afferens of gill filaments. The mature myxospores of this species were pyriform in shape and 19 ± 0.6l (18–19.5) long, 8.2 ± 0.54 (7.5–9) wide, 7.3 ± 0.25 (7–7.5) thick containing polar tubules with 9–10 turns. The plasmodia of Thelohanellus cf. fuhrmanni were collected from under the skin of snout of the common nase. The myxospores were pyriform, 16.3 ± 0.39l (15.5–16.5) long, 6.5 ± 0.55 (6.3–7) wide, 6.3 ± 0.53 (5.8–7) thick containing polar tubules with 6 turns. Small subunit ribosomal DNA sequences of both Thelohanellus species differed from other known myxozoans. The myxospores morphology, histopathology and ssrDNA sequences supported a diagnosis of T. pyriformis from tench and T. cf. fuhrmanni from common nase. [Display omitted] • Two Thelohanellus spp. were redescribed from cyprinid fishes. • Thelohanellus pyriformis was recorded and described from the type host tench (Tinca tinca). • Thelohanellus cf. fuhrmanni was found in an atypical host, common nase (Chondrostoma nasus). • The morphology of both Thelohanellus species was supported by histology and ssrDNA sequence data. [ABSTRACT FROM AUTHOR]

Purpose. Forming a thematic bibliographic list of publications on the morphological, ecological, physiological and biochemical characteristics of the tench (Tinca tinca L.), its cultivation and the state of its stocks in natural water bodies. Methodology. The complete and selective methods were applied in the process of the systematic search. The bibliographic core has been formed with the publications exclusively in Ukrainian and Russian from the fund of scientific library of the Institute of Fisheries NAAS of Ukraine. Practical value. The list may be useful for scientists, practitioners, students, whose area of interests includes the study of physiological, biochemical, ecological and other characteristics of cyprinids, in particular tench, as well as the restoration of its stocks.

Tench is a cyprinid fish that has undergone human-induced translocations. The natural populations of the species are on the decline due to habitat loss and spawning grounds degradation. The genetic diversity of seven natural populations was investigated to establish the genetic knowledge base for successful conservation efforts and for selective breeding. Twelve microsatellite markers, the sequencing of a 615 bp section of mtDNA (Cytb) and PCR-RFLP analysis of two nuclear markers (Act) and (RpS7) were used to analyze the genetic variation and structure among 175 individuals. All microsatellite loci were found to have moderate levels of polymorphism. The pairwise Fst values between population pairings were moderate; the populations were aligned to four clusters. The Cytb gene showed 20 haplotypes; 67.1% of individuals were categorized as Eastern, while 32.9% to the Western haplogroup. Analysis of the Act and RpS7 genes showed that the level of hybridization among the two haplogroups is high within the sampled populations. Hungarian Tench populations are genetically less diverse compared to natural populations in Western-Europe, but they still represent valuable genetic resources and Lake Fertő, Lake Kolon and Csörnöc-Herpenyő populations can be optimal candidates for future selective breeding programs. [ABSTRACT FROM AUTHOR]

Fishery residues are abundant raw materials that also provide numerous metabolites with high added value. Their classic valorization includes energy recovery, composting, animal feed, and direct deposits in landfills or oceans along with the environmental impacts that this entails. However, through extraction processes, they can be transformed into new compounds with high added value, offering a more sustainable solution. The aim of this study was to optimize the extraction process of chitosan and fish gelatin from fishery waste and their revalorization as active biopolymers. We successfully optimized the chitosan extraction process, achieving a yield of 20.45% and a deacetylation degree of 69.25%. For the fish gelatin extraction process, yields of 11.82% for the skin and 2.31% for the bone residues were achieved. In addition, it was demonstrated that simple purification steps using activated carbon improve the gelatin’s quality significantly. Finally, biopolymers based on fish gelatin and chitosan showed excellent bactericidal capabilities against Escherichia coli and Listeria innocua. For this reason, these active biopolymers can stop or decrease bacterial growth in their potential food packaging applications. In view of the low technological transfer and the lack of information about the revalorization of fishery waste, this work offers extraction conditions with good yields that can be easily implemented in the existing industrial fabric, reducing costs and supporting the economic development of the fish processing sector and the creation of value from its waste.

Background: The aquatic environment is continuously being contaminated with toxic chemical substances from industrial, agricultural and domestic activities. The identification of different biomarkers of such contamination is of great relevance to determine the potential impact of those xenobiotics on the health of organisms. Objective: To estimate the suitability of different biochemical brain biomarkers from tench in order to evaluate the environmental effect of an exposition to different concentrations of the pesticide carbofuran. Methods: The present study focused on the effect of a long-term exposure (28 days) to different concentrations (50, 100 and 200 μg/L) of the pesticide carbofuran on certain biochemical parameters of tench (Tinca tinca L.). Selected biomarkers for stress monitoring were malondialdehyde (MDA), as index of lipid peroxidation, and reduced glutathione (GSH). Moreover, acetylcholinesterase (AChE) activity was quantified as biomarker of effect on fish nervous system. Results: AChE activity was significantly inhibited in fish exposed to all concentrations of carbofuran after 14 and 21 days of exposure, returning to basal levels after this period with 50 and 100 μg/L. Moreover, significant decreases of MDA levels could be detected after 14 and 21 days of exposure to 200 μg/L, lasting until the end of the experiment. GSH levels decreased after 14 and 21 days of exposure to 100 and 200 μg/L; nevertheless, GSH recovered basal levels at the end of the experiment. Conclusion: All the three biochemical parameters assessed -mainly inhibition of AChE activity- could be adequate biomarkers of early exposition (less than 14 days) to low doses of carbofuran in biomonitoring programs, being MDA reduction also related to longer exposure.

Flow cytometry is an effective and widely used tool for determination of ploidy in fish, but it is not always possible to access the fresh samples for analysis. We investigated the potential for extended storage of fish tissue with sterlet and tench as representative species of Chondrostei and Teleostei, using blood and fin of subadult/adult specimens and tail of larvae. Thirteen procedures for extending storage, selected for rapidity and simplicity in both field and laboratory conditions, were tested for each tissue sample. Flow cytometry was applied to fresh tissue immediately after sampling and to tissue subjected to experimental protocols, always along with species‐specific standard, after 1, 5, and 10 days storage at 0–4°C or freezing at −80°C. The fluorochrome 4′,6‐diamidine‐2′‐phenylindole dihydrochloride was used with excitation/emission maximum 358/461 nm. Based on the measurability of stored samples, evaluation of directly measured coefficients of variation of their DNA peaks and the changes in fluorescence intensity compared to fresh tissue, optimal procedures for extended storage of the selected tissue types of the model species are suggested. © 2020 The Authors. Cytometry Part A published by Wiley Periodicals LLC. on behalf of International Society for Advancement of Cytometry. [ABSTRACT FROM AUTHOR]

At present, the role of erythrocyte magnesium in the respiratory processes of fish (and other animals) under conditions of stress load is not known. This article presents the results of research on change in the concentration of magnesium in erythrocytes under the action of stressors of different quality and quantity for bream (Abramis brama L.), silver crucian carp (Carassius auratus gabelio Bloch) and tench, (Tinca tinca L.) in Rybinsk Reservoir. The concentration of magnesium ions was analyzed on an atomic absorption spectrometer AAS-1 manufactured by Carl Zeiss (Germany) in the absorption regime in an air-acetylene flame. For the first time, the dependence of the change in magnesium concentration in erythrocytes on the intensity of the stress load of different nature on the example of fishes was revealed. Weak and moderate strength effects (low doses of epinephrine, norepinephrine, small changes in water temperature, saline injection, prick into the abdominal cavity, short-term removal of fish from the water, short-term keeping of fish in a limited volume of water) increased the concentration of magnesium in erythrocytes up to 2.5 times. At the same time, an increase in the affinity of hemoglobin for oxygen and a decrease in oxygen consumption were observed. However, strong stressors such as catching, transporting fish to the laboratory (representing complex effects of hypoxia, limited water volume, mechanical effects, etc.), as well as a sharp and large change in water temperature, high doses of adrenaline reduced the concentration of magnesium in erythrocytes 3 times. At the same time, the hemoglobin affinity for oxygen decreased and oxygen absorption increased. However, before the death of fish (from exhaustion), with a low level of magnesium in erythrocytes the affinity of hemoglobin for oxygen increased and the intensity of gas exchange decreased. The research conducted allow us to consider the change in the concentration of magnesium ions in erythrocytes – which are positive modulators of the affinity of hemoglobin for oxygen – in fish exposed to stress as one of the mechanisms for reducing the gas exchange intensity for weak and medium short-term stress effects and increasing it for strong short-term ones. Especially important is the role of erythrocyte magnesium as a molecular mechanism for reducing oxygen uptake and, consequently, increasing anabolism and, thus, increasing the growth and development of animals under the action of mild, short-term stressors, i.e. with eustress. In addition, the concentration of magnesium in erythrocytes can serve as an indicator of the state of fish. A high level of this cation in erythrocytes (1.5–2.0 times higher and more than normal) is characteristic for strong, healthy animals in a state of eustress or physiological stress, and extremely low values of this indicator (1.5–2.0 and more times below the norm) are an indicator of reversible or permanent ill-being (distress or pathological stress). Weakened, exhausted animals are not capable of a response to eustress or physiological stress. The possible causes of low magnesium concentrations in human erythrocytes are discussed.

The results of a profitable fish farming are based in the first place, on the genetic quality of fish (growth rate, prolificity, disease resistance, etc.) The genetic improvement of the fish is a continuous preoccupation at the global and national level, intending to create new, highly productive races and hybrids. The morphologic characterization used as an instrument of work in the evaluation of the morphometric changes of fish, is based on biometry. The study presented achieves a morphometric characterization of the tench through the classic biometric method and tests the possibilities of using 3D photographic method for fish measureing. The results show that the classic biometrics method with a high degree of aggression on fish, can be replaced with the 3D photometric method, used through an application on the mobile phone, that achieves better accuracy, saves time and completely avoids the stress and fish losses. [ABSTRACT FROM AUTHOR]

The tench Tinca tinca is a freshwater species with human‐mediated translocations, aquaculture interest and limited information on its genetic structure. mtDNA sequencing analysis of control region and two genes in 50 individuals from five European populations identified two phylogroups, with greater variability than that reported until now, and a hybridization zone in the Danube River region. Restriction analyses of additional samples reveal the complicated genetic structure characteristics of tench's wild and translocated populations, supporting future breeding practices. [ABSTRACT FROM AUTHOR]

Laboratory experiments have indicated that tench (Tinca tinca) is an effective predator of Potamopyrgus antipodarum. However, few P. antipodarum have been found in the gastrointestinal tracts of wild caught benthivorous fishes, including tench. This had led to the assumption that the shell properties of the snail act against native predators. In general, it has been predicted that this is due to P. antipodarum possessing a thicker shell and a lower amount of soft tissues than native snails; the latter will thus be preferred by benthivorous fishes. In the current study, shell-crushing resistance and the soft tissue mass / shell mass ratio were compared between the non-native P. antipodarum and three native species. Results indicated a similar shell-crushing resistance for P. antipodarum relative to the native Bithynia tentaculata, the latter of which is a common food object in tench diet. However, the soft tissue mass / shell mass ratio of the invader was significantly lower than in most of the studied native snails, indicating a lower amount of soft tissues in P. antipodarum. [ABSTRACT FROM AUTHOR]

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The purpose of this research was to study the free radical induced lipid oxidation in the commonest fish species inhabiting the Volga river, in the Middle Volga region of the Russian Federation, depending on the seasons of the year. The commonest fish species in the Volga river basin: European carp Cyprinus carpio (L., 1758), sabrefish Pelecus cultratus (L., 1758), common bream Abramis brama (L., 1758), tench Tinca tinca (L., 1758), and common roach Rutilus rutilus (L., 1758) were studied. The level of malondialdehyde and the activity of catalase were investigated in gills, liver, muscles and gonads. The values of molecular oxidative biomarkers in the studied fish species were significantly higher in the summer, suggestinga more active lipid peroxidation. The increase in catalase activity in the studied organs may indicate activation of the antioxidant defense system that can positively affect the growth and development of fish. [ABSTRACT FROM AUTHOR]

The growing economic interest in tench has led to the need for further information on the best slaughter methodologies for this species in order to respect animal welfare and preserve fillet quality. Sixty farmed tench ( Tinca tinca ) were randomly divided into three groups of killing: carbon monoxide (CO), electrical (ES) and percussive (PS) stunning. The behaviour of the fish, the onset of rigor mortis and the gill cortisol concentration were determined as stress indexes, while after rigor resolution, the quality of the fillets were followed over a period of 10 days of refrigerated storage (+2.5 °C) by determining physical and chemical properties of the fillets. The observations indicated that the fish did not seem to perceive CO negatively, and normal swimming activity was recorded. No external or internal damage was recorded for any of the killed fish. The evolution of the rigor mortis index indicated that CO reached full rigor at about 15 h post mortem , that is, an intermediate value was reached between ES (9 h) and PS (19 h). The fish stunned with CO showed significantly lower gill cortisol level than the ES and PS ones, that is, 0.408, 0.453 and 0.455 ng/mg protein, respectively. As far as the quality parameters are concerned, the slaughter method significantly affected pH, redness (a*) and yellowness (b*). No differences in pH were recorded for the killing procedures at the end of rigor resolution, whereas CO derived flesh presented the lowest pH from the second day till the end of the storage, when values of 6.44, 6.51, and 6.60 pH were found for CO, ES, and PS, respectively. The CO flesh presented the most stable redness index over the whole trial and the lowest b* value from the beginning. The drip loss values were unaffected by the killing method, but increased significantly with the storage time. Neither the slaughter method nor the storage negatively impacted on the fatty acid composition, which resulted to be equally rich in PUFA n3 and n6 (around 40 g/100 g total fatty acids). A numerical difference in the secondary lipid oxidation products emerged for the different killing groups at the end of the refrigerated storage. The CO flesh was the least oxidized, with the samples showing 1.33 mg MDA-equivalents/100 g muscle against 1.60 and 1.55 found for ES and PS, respectively. [ABSTRACT FROM AUTHOR]

The aim of this study was to examine the pathological findings of 30 naturally infected tench (Tinca tinca) with Ligula intestinalis plerocercoids from Golhisar Lake (Burdur) in Mediterranean Area of Turkey. Clinically and macroscopically, poor and irregular swimming, hemorrhages at the bases of fins and around the anus, the presence of the plerocercoids in the viscera together with perivisceral hemorrhages and distension of abdomen were generally observed in the diseased fish. Microscopically, hemorrhages, necrosis and mononuclear cell infiltrations were seen in the viscera invaded by plerocercoids. In conclusion, the cestode Ligula intestinalis plerocercoids' pathological effects on the tench tissues were widely evaluated for the first time in Turkey. [ABSTRACT FROM AUTHOR]

Bu çalışmada, Seyhan Baraj Gölü’nden Eylül 2006-Ağustos 2007 tarihleri arasında yakalanan 170 adet Kadife balığı (Tinca tinca (Linnaeus, 1758)’nın et verimliliği ile çeşitli vücut organları arasındaki ilişkiler incelenmiştir. Kadife balığı bu bölgede ekonomik öneme sahip bir türdür. Yapılan inceleme sonucunda, ortalama baş ağırlığı/vücut ağırlığı oranı % 11,15; iç organların ağırlığı/vücut ağırlığı % 8,93; yüzgeç ağırlığı/vücut ağırlığı % 2,77 ve et verimliliği % 77,07 olarak bulunmuştur. Kadife balığı popülasyonunun I-V yaşları arasındaki et verimliliği, yüzde olarak sırasıyla % 70,66, % 75,70, % 77,28, % 77,38, % 80,70 şeklinde belirlenmiştir. Sonuç olarak yaş arttıkça et verimliliğinin arttığı görülmüştür

Tench production is limited in traditional and low intensity cultures. However, its demand is increasing and makes necessary the evaluation of physiological parameters that could affect tench welfare under intensive conditions. This study analyses the growth performance and related indices, hematological and immunological parameters as well as hormone profile and electrolytes in plasma, in fish under three different culture systems: extensive (E), with initial density of 0.07 kg/m 3 , no control of environmental parameters and natural feeding; semi-intensive (SI), with initial density of 0.42 kg/m 3 , partial control of temperature and supplementation of artificial food; and intensive (I), with initial density of 2.5 kg/m 3 , total control of photo- and thermo-period and exclusive artificial diet. Results showed that variables such as weight, length, density increase and specific growth rate (SGR) were higher in I. Higher hepatosomatic index were found in I and SI. In addition, E and SI cultures, which kept natural conditions, achieved greater gonadal increase in detriment of somatic growth. On the other hand, the analysis of hormones and electrolytes, hematological and immunological parameters did not reveal a disturbed immune function in I compared to SI and E. Thus, the general activation of the nonspecific immune system and the mobilization of energy reserves associated to gonadal maturation in fishes from S-I and E systems could be related to an adaptive, non-pathological, response to the natural environmental changes, resulting in reduction of productivity. With all in mind, it can be concluded that adequate artificial feeding and control of the environmental parameters can improve tench productivity by intensive systems without major perturbations of its welfare. [ABSTRACT FROM AUTHOR]

A globally invasive fish, Eurasian tench ( Tinca tinca) is spreading through the St. Lawrence River and poses an imminent invasion threat to the Great Lakes. Following its illegal release into a tributary of the St. Lawrence River in 1991, tench has spread throughout the river's main stem over the past decade, and its abundance in commercial fishing bycatch in the river has grown exponentially. The tench is a generalist benthic consumer with largely undocumented ecological impacts in North America. Reports from other invaded regions indicate that it can compete with other benthic fishes, host a diverse assemblage of parasites and pathogens, degrade water clarity in shallow lakes, limit submerged macrophyte growth, reduce gastropod populations, and promote benthic algal growth through top-down effects. Risk assessments and climate-match models indicate that the Great Lakes are vulnerable to tench invasion, and they signal the need for timely comprehensive actions, including development and implementation of monitoring and rapid-response protocols, including prevention or slowing of natural dispersal through canals. [ABSTRACT FROM AUTHOR]

The nutritional profile and the consumer preference of fish burgers made from carp, goldfish, perch, and tench were investigated. Perch and goldfish burgers, which have the highest proportion of eicosapentaenoic acid (6.63% and 4.90%, respectively) and docosahexaenoic acid (20.28% and 11.99%, respectively), showed lower absolute amounts of these fatty acids (17.03 and 10.10 mg/100 g food, respectively) than tench and carp (31.16 and 49.63 mg/100 g food, respectively). The consumer evaluation established that differences in the perception of the fish burgers exist. The overall liking and taste were the main attributes that influenced both consumer’s acceptance and purchase intent. [ABSTRACT FROM PUBLISHER]

Homogeneous background (age, sex, genetic lineage, culture conditions) was created to clearly demonstrate the impact of the tested dietary treatments. No feeds optimized for the rearing of the tench ( Tinca tinca L. 1758) are available. Feeds are formulated to increase the growth rate or eliminate skeletal deformations. With the increasing prices of the basic components, fish meal ( FM) and fish oil, poultry by-product meal ( PBM) can be used. The aim of the study was to evaluate the effects of substitution of FM with PBM on the tench blood parameters, body composition and structure of skeletal muscles. Cage-reared female tenches (325 ± 18 g) were fed for 86 days with five types of feeds with 0% (control), 25.7%, 48.6%, 71.4% and 100% substitution of FM with PBM. No significant differences between the formulations were reported for weight, total length, fillet weight, visceral, liver, gonado-somatic, proximate composition and biochemical blood parameters. However, significant differences were found in the fillet profiles of fatty acids-an increase in the PBM content correlated with an increase in saturated and monounsaturated fatty acids and a decrease in n-3 PUFA and, generally, n-6 PUFA. Significant differences were also observed in, for example, the content of intramuscular fatty tissue and the level of organ lipidosis between the control variant (0% PBM) and that with 100% substitution. A sensory assessment indicated a higher gustatory value of the fillets in the case of feeds with 48.6% and 71.4% substitution. [ABSTRACT FROM AUTHOR]

Tench, Tinca tinca is a freshwater species which receives increasing attention as marine resources are overexploited and alternative feed components must be implemented to enable sustainable development of aquaculture. The aim of the study was to provide scientists and fish farmers with first high quality annotated tench transcriptome and open a new chapter in tench research, especially when practical diets are tested. Therefore, the second aim was to identify differentially expressed contigs (DECs) in tench gut after 86-day trial where adult tench females were fed with 0% and 100% replacement of fish meal (FM) with poultry by-product meal (PBM). De novo assembling using de novo RNA-Seq Assembly Pipeline (DRAP) produced 64070 contigs where these exceeding 1 kbp were mostly annotated. Microsatellite search identified 23668 SSRs and SNPs were distributed in 118002 transitions and 83577 transversions. High quality of the assembly and annotation completeness of the tench transcriptome was confirmed using BUSCO and by mapping contigs against common carp, Cyprinus carpio and zebrafish, Danio rerio data sets. Analysis of gene expression differences between gut samples tench fed with FM and PBM diets revealed 721 and 69 DECs using edgeR and DESeq2, respectively. Venn diagram for these results filtered out 57 DECs which were common for both analysis. Due to a low number of annotated DECs enrichment analysis provided a low number of useful contigs for pathway or functional analysis. Nevertheless, each contig in the set was analysed through BLASTn and BLASTx and eighteen DECs were characterised and identified as mainly involved in response to different immune stimuli and disease states (e.g. cluster of differentiation 48 , F-type lectin ), cell adhesion (e.g. paracingulin ), digestion (e.g. serine proteases) and signal transduction (e.g. neurexophilin 3 , complexin 2 ). Moreover, study has shown that most of the identified in our study DECs (70.2%) were down regulated in gut samples of tench fed with PBM comparing to these with FM-based feed. This observation might indicate on disorganization of inter-epithelial junctions in ongoing inflammation process. Our de novo tench gut transcriptome assembly (online NGS Pipeline) provide a guide for further diverse studies because, understanding feed-gut interactions and intestinal homeostasis in farmed tench is important to maximise performance of this species and to ensure that freshwater aquaculture continues to be a sustainable source of food for a growing world population. [ABSTRACT FROM AUTHOR]

A 16-day experiment was designed to find the best combination of water temperature (27, 30, 33°C) and daily duration of food availability (12, 18, 24 h) for larval tench ( Tinca tinca) growth and survival. Larvae with an initial mean size of 5.7 mm total length ( TL) and 0.7 mg wet body weight ( BW) were stocked at 15 L−1. Larvae were fed in excess with live Artemia nauplii with the period of food availability lasting 12, 18 or 24 h daily. The largest final larval size was recorded at 27 and 30°C in groups fed for 24 h a day (17.7 and 17.9 mm TL, 76.1 and 77.7 mg BW, respectively). The combination of the highest temperature and the longest daily food availability was the only set of conditions under which final larval survival was affected (95.4% survival; 98.7-99.9% under all other conditions). The combination of water temperature of about 28.6°C and continuous food availability is recommended as the optimum combination for rearing T. tinca larvae under controlled conditions. Providing continuous food supply to fish larvae under aquaculture conditions was also advantageous in helping to mitigate the effects of slower growth relative to developmental progress, which can occur at high water temperatures. However, should one wish to limit the daily feeding period to 12 h per day, the use of a water temperature between 27.4 and 27.9°C would be the best solution. [ABSTRACT FROM AUTHOR]

The aim of this study was to detect the correlation between the change in the ambient temperature and adaptation of the pronephros - the main haematopoietic organ in fish, which so far has not been subject of research. Compared with other teleosts and their number of blood cells in peripheral blood, tench (Tinca tinca L. 1758) showed the corresponding trend of changes in number of pronephros haematopoietic cells after exposure to increased water temperature. The number of all haematopoietic cell lines was changed during the conditions of thermal stress (P<0.01; P<0.05). The number of erythroblasts was significantly reduced due to shift of haemoglobin curve of dissociation to the right. Leukopoietic cells were increased significantly as a response of pronephros to stress and all endocrine mediators of the stress (cortisol, leukine, etc.). The number of prothrombocytes was slightly decreased due to mobilisation into peripheral blood as in the case of cell precursor of monocytes. Eosinophilic and basophilic granuloblasts were not found in tench pronephros. Correlation (R²) between body mass and total length was 0.526. Sex-specific variation of haematopoietic cells number in the same group was not observed (P>0.05), but it was significant between males or females among different groups (P<0.01; P<0.05 respectively). [ABSTRACT FROM AUTHOR]

The impact of treatment with mGnRHa, mGnRHa with metoclopramide, and metoclopramide on secretion of luteinizing hormone (LH), testosterone (T) and 11-ketotestosterone (11-KT) and on milt and spermatozoon characteristics was studied in male tench Tinca tinca . Male tench were divided into four groups and treated with following preparations: 0.9% NaCl; mGnRHa (25 μg kg − 1 ); mGnRHa (25 μg kg − 1 ) combined with metoclopramide (20 mg kg − 1 ); and metoclopramide (20 mg kg − 1 ). Administration of the combined treatment induced an LH surge at 12 h post injection (PI) reaching significantly higher values ( P < 0.05) than was observed with stimulation by mGnRHa alone or with metoclopramide alone. Monitoring of LH levels demonstrated a rapid surge in LH release with the combined treatment versus gradual increase with mGnRHa alone ( P < 0.05). Experimental treatments with GnRHa alone, metoclopramide alone and metoclopramide combined with mGnRHa significantly increased milt production and relative number of spermatozoa kg − 1 BW at 24 h PI compared to controls, with no differences among experimental groups ( P < 0.05). No significant differences among groups ( P < 0.05) were found in motility or velocity (VLC, VAP, VSL). The only significant decrease of VLC and VAP was detected after treatment with metoclopramide alone compared to all other groups. Nonsignificant differences ( P < 0.05) were observed in T and 11-KT secretion, with the exception of a significant difference in T secretion ( P < 0.05) at 24 h PI between the combined group and the metoclopramide treatment and the controls. We conclude that the use of GnRH, combined or not with metoclopramide, are suitable hormonal treatments to control the spermiation in mature tench. [ABSTRACT FROM AUTHOR]

The experiment was designed to determine the combined effect of fish diet and water temperature on juvenile tench Tinca tinca (L.). Three diets were used: commercial dry diet for fish Aller Futura (diet F); frozen Chironomidae larvae (diet C); and Aller Futura substituted with Chironomidae at a ratio of 3:2 (dry weight; diet FC). Daily food rations and duration of the experiment were adjusted to temperatures of 20°C, 23°C and 26°C based on a correction factor q equal to 1.000, 0.779 and 0.609 respectively. The experiment lasted 92, 72 and 56 days for the respective temperatures. No mortality occurred. The highest relative growth rates were found at 26°C in diets F and FC. The lowest food conversion ratio of 1.12-1.22 (recalculated for dry weight of feed diet) was determined in fish fed diet F at 23°C and 26°C. A high value of condition index appeared to be the early warning of decreasing biological quality of fish and deformities. The lowest incidence of fish with deformities ( IDef) was found in groups fed diet C (<1%), while the highest (90%) in fish fed diet F at 26°C. A lower share of dry diet in the fish food and a lower water temperature led to a lower IDef. Thus, amount of dry feed in fish diet was the major factor inducing body deformities, while water temperature only modified the effects of the dietary factor. Diet C at 23-26°C was the most cost-effective of the tested combinations of diet and temperature. [ABSTRACT FROM AUTHOR]

The studies on the ichthyofauna of Serbia that have been conducted so far indicate the sporadic tench (Tinca tinca L.) presence in typical habitats. The hydroenvironmental conditions necessary for the survival of this fish species are highly variable and, generally, are more favourable in the northern part of the country (the Vojvodina Province). Although the tench presence has been registered at over 30 sites, there is a tendency of a decrease in population abundance. This is due to the reduction of the surface area of the macrophyte-covered flood zones induced by the damming and regulation of rivers, high water level fluctuations, and water amount reduction in the majority of watercourses, a massive increase in the number of allochthonous phytofagous species, reservoir sediment deposition, water quality deterioration and other factors. The tench conservation status in Serbia is officially designated as Low Risk - Least Concern. It may be transferred to a higher category if the tendency towards deterioration of survival conditions for the species should continue.

In this study, metazoan parasites of tench (Tinca tinca L., 1758) in the Lake Sapanca were investigated between April 2005 and March 2006. A total of 57 tench were examined and 7 parasite species were recorded including; Dactylogyrus macracanthus, Wegener, 1909 (Monogenoidea) prevalence 26.3% mean intensity 9.06 ± 7.362, Asymhylodora tincae (Modeer, 1970) 61.4%, 92.6 ± 84.107, Diplostomum sp. 12.3%, 2.3 ± 1.069 (Trematoda), Caryophyllaeus laticeps (Pallas, 1781) 8.7%, 7.2 ± 7.127 Bothriocephalus acheilognathi (Yamaguti, 1934) 3.5%, 4 ± 4.242 (Cestoidea), Ergasilus sieboldi Nordmann, 1832, 1.7%, 2 (Crustacea) and glochidia of mollusk 8.8%, 13.8 ± 12.421 (Bivalvia).

The aim of the study was to compare physiological statuses of stripped and not stripped tench females with ovulation induced by GnRHa or carp pituitary extract (CPE). The comparison was based on selected biochemical stress indices (cortisol, glucose), condition (TP, TGA), and cell membrane characteristics (ALT, AST, CK). In the first and in the second year, 37 and 29 tench females were monitored, respectively. No differences in the values of biochemical parameters in either period were found between the two groups of stripped female tench whose ovulation was induced by GnRHa and CPE, respectively. No significant differences in TP, TGA, ALT, AST and CK values were found between the groups of stripped and not stripped females with ovulation induced by GnRHa or CPE. Different values were found in stress indices, specifically in glucose concentrations. A significant increase (P < 0.01) in glucose concentrations was found in tench females immediately after stripping and, in not stripped females, about 48 hrs after ovulation induction. Both artificial stripping and the inability to release eggs are important stress factors for female tench.

In the present study, the effects of sub-lethal sub-chronic doses of ibuprofen, diclofenac, and carbamazepine alone, and in combination (concentration range 0.02-60 µg/l), on the early life stages of tench (Tinca tinca) were investigated. The lower concentrations of pharmaceuticals tested (0.02, 0.2, 2 µg/l) represent the concentration values of these substances commonly present in surface waters or effluents from wastewater treatment plants. Multiple biomarkers of biotransformation, antioxidant defence systems, and lipid peroxidation were determined in fish after 35 days of exposure. The evaluated pharmaceuticals induced oxidative stress in fish both alone and in combination with each other. Generally, 60 µg/l of each single pharmaceutical influenced the activity of antioxidant enzymes significantly (P < 0.05), whereas the same concentration of these pharmaceuticals in combination (1 : 1 : 1) did not have any impact on the activity of these enzymes. However, changes in biotransformation and antioxidant enzymes were apparent if lower concentrations of these pharmaceuticals were administered in the mixture. Significant changes (P < 0.05) in the activities of glutathione reductase, glutathione peroxidase, and glutathione-S-transferase were observed even at environmental concentration ranges. A significant effect (P < 0.05) on lipid peroxidation levels was found only in the experimental group exposed to carbamazepine. [ABSTRACT FROM AUTHOR]

Experiments were carried out to develop an optimal cryopreservation protocol for tench sperm by testing the fertilizing capacity and motility parameters including progressive motility, curvilinear velocity ( VCL) and linearity ( LIN) of cryopreserved sperm. Three experiments were designed to this aim: first experiment where we tested the effects of two extenders (sugar-based Grayling and ion-based Kurokura 180) and two cryoprotectants ( DMSO and methanol) on fertilization and hatching success; second where we tested the effect of cryoprotectant type (methanol or DMSO) in different concentrations (5%, 10% and 15%) on fertilization and hatching success; and third where we tested the effect of two cryoprotectants (methanol and DMSO) on sperm motility parameters (progressive motility, VCL and LIN) after 4 h post-thaw storage (4°C). Sperm prepared with the sugar-based Grayling extender displayed better fertilization and hatching rates independently of the applied cryoprotectant most likely due to glucose present which acted as an external cryoprotectant. Concerning cryoprotectant concentrations, the use of 10% methanol yielded the highest fertilization (85 ± 15%) and hatching (80 ± 13%) rates, which were significantly higher than in all other groups. During the post-thaw storage time, 5% methanol, 10% methanol and 5% DMSO groups had significantly higher motility parameters than other groups and we observed no significant decline in any of the parameters during the storage time. Overall, we found that a sugar-based extender in combination with methanol as cryoprotectant is suitable for the cryopreservation of tench sperm and allows storage of cryopreserved sperm for up to 4 h post thaw. [ABSTRACT FROM AUTHOR]

Background. Water temperature is a major factor regulating fish metabolism. It can influence body chemical composition and the incidence of body deformities. The latter often develop in farmed fish and this issue is currently emerging as a serious problem for aquaculture. Determining the effects of water temperature on body chemical composition and fish body deformities is an important subject for research in fish biology and nutrition, and aquaculture. The presently reported study was conducted using juvenile tench, Tinca tinca (Linnaeus, 1758), an important aquaculture species in Europe. Two hypotheses were tested: 1) temperature can significantly influence body chemical composition and the incidence of body deformities in fish; 2) the effects of temperature on fish depend on their diet. Material and methods. Fish, with an initial total length of 28.4 ± 2.7 mm and body weight of 0.24 ± 0.07 g, were reared at 20, 23, and 26°C and fed dry feed Aller Futura (Aller Aqua, Denmark) only, or a combination of this feed and natural food (frozen larvae of Chironomidae) in a 3 ÷ 2 ratio of dry matter, or the natural food alone. The duration of the experiment and the daily food rations were adjusted to the experimental temperatures based on a correction factor, q, of 1.000, 0.779, or 0.609, respectively. The experiment duration was 92, 72, or 56 days for the respective temperatures. Results. Body deformities occurred in all groups of fish fed solely or partially with the dry diet (21.5%-89.5%). The incidence of deformities was directly proportional to the temperature and the content of dry feed in the diet reaching the maximum in fish fed exclusively the dry diet at 26°C. Water temperature and fish diet influenced body chemical parameters (moisture, protein, lipid, ash, Ca, P, Mg, Ca ÷ P, Mg ÷ P), but water temperature did not have a significant effect on whole-body P content. Conclusions. Water temperature proved to significantly influence fish chemical body composition and the incidence of body deformities in fish fed dry diet. The major factor that caused fish P deficiency, and resulted in low body ash content and body deformities, was insufficient bioavailability of P in the dry diet. Water temperature appeared to only modify P deficiency symptoms in fish. [ABSTRACT FROM AUTHOR]

Teleost fish include many different species, having a large economic and environmental impact. Glucose is a key source of energy for most vertebrate organisms. Fish as well as mammals maintain a specific level of blood sugar - glycaemia, which is influenced by multiple factors such as hormone production, diet, and temperature. Therefore, it is a useful indicator for scientists who need to check the immediate state of an organism. The most frequently used method of measuring glycaemia in farmed fish is spectrophotometry; however, this method is often inconvenient for field experiments. Here we report that basic spectrophotometry using oxidation of blood beta D-glucose by glucose oxidase (used in laboratory conditions) can be easily substituted with portable glucometer measurements, primarily designed for human samples. The possibility of use outside the laboratory and its small sample volume demands make this method very useful. Field studies often require fast sample processing and conditions of measurement are limited. Using the glucometer is a simple and elegant option. We tested 74 blood plasma samples (29 males, 45 females) of tench (Tinca tinca) both spectrophotometrically and using the human glucometer. Our results show a significant linear correlation (P < 0.001) between both methods. The main contribution of this study consists in comparability and interchangeability of results obtained from both presented methods. [ABSTRACT FROM AUTHOR]

The study evaluated the impact of mGnRHa ([D-Tle 6 , Pro 9 , NEt]-mGnRH), with or without metoclopramide, on release of luteinizing hormone (LH) and sex steroids and on viability of ova in tench Tinca tinca . Four experimental groups were subjected to the following treatments given as intraperitoneal injection: 0.9% NaCl (C); 25 μg kg − 1 mGnRHa (Gn); 25 μg kg − 1 mGnRHa with 20 mg kg − 1 metoclopramide (GnM); and or 20 mg kg − 1 metoclopramide (M). GnM treatment induced LH surge reaching maximum concentrations 6 h post-treatment followed by a slight but significant decline ( P < 0.05). Gn group showed gradually increasing LH values ( P < 0.05). No significant differences were found between GnM and Gn treated groups in 17β-estradiol (E 2 ) or testosterone blood level. Significant decrease from baseline ( P < 0.05) was found in E 2 values at the end of trial period in both Gn and GnM. Testosterone values increased with Gn and the GnM, peaking 12 h post-treatment and dropping to baseline levels at 24 h. GnM was associated with significant increase of 17α, 20β-dihydroxy-4-pregnen-3-one (17,20 β -P) values at 6 h ( P < 0.05), with its concentration peaking at 12 h similar to that in Gn. Both treatments induced ovulation in a high proportion of females, while M and C group showed no ovulation. No significant differences were found in ovulation rate, latency, ovum weight, or relative fecundity. Nevertheless, significant differences ( P < 0.05) between Gn and GnM treatment were observed in fertility (77% vs. 54%) and hatching (40% vs. 23%). GnM stimulated rapid LH release with a potentiating effect on 17,20 β -P secretion, possibly the source of the adverse effects on ovum viability. We describe for the first time the negative impact of metoclopramide combined with mGnRHa hormone treatment on ovum quality in tench. Statement of relevance Improvement of fish artificial reproduction. [ABSTRACT FROM AUTHOR]

The tench ( Tinca tinca L., 1758) is a promising freshwater species in which numerous studies have been conducted recently to develop a dedicated feed for optimized growth rate. The aim of this study was to assess the stability of seven candidate reference genes, including 18S ribosomal RNA (18S rRNA), β-actin ( actb ), α-tubulin ( tuba ), ribosomal protein l8 ( rpl8 ), 40S ribosomal protein s11 ( rps11 ), glyceraldehyde-3-phosphate dehydrogenase ( gapdh ) and elongation factor 1 alpha ( ef1a ), to select the best calibrator for nutrigenomic studies that would improve our understanding and illustrate the molecular basis of nutrient-related gene expression in response to feed mixes in the tench. An additional aim was to verify the hypothesis that the functioning of the somatotropic axis in the tench (growth hormone receptor, ghr , and growth hormone, gh ) depends on dietary treatment. The analysis was based on five tissue samples (liver, spleen, gut, heart and muscle) collected from adult tench females fed with 0% and 100% replacement of fish meal (FM) with poultry by-product meal (PBM). The study demonstrated that the most stable genes in most tissues were rpl8 and rps11 , with gapdh showing the greatest stability, along with rpl8 , in the liver. Moreover, a comparison of relative transcript abundance between the tissues revealed that ghr demonstrated the highest expression in the liver, while gh demonstrated the highest expression in the spleen. Based on the selected reference genes, it was determined that the feed did not affect the level of expression of ghr and gh in most tissues except the spleen ( ghr ). The study also involved a phylogenetic analysis based on the amino acid sequences of Rpl8 , Rps11 and Ghr , and it was confirmed that the tench is the most closely related with Asian cyprinids (i.e. Megalobrama amblycephala ). The study identified suitable reference genes for RT-qPCR in the tench, and the effect of two feed variants on the somatotropic axis was determined. The study opens the way for further nutrigenomic studies aimed to develop a feed best matched for the needs of the tench and optimizing its growth. Statement of relevance The effect of feed intake on gene expression in fish species is of particular interest of aquaculture sector which seeks for alternative protein sources, but also new species to adapt for intensive culture. The study demonstrated that the most stable genes in most tissues were rpl8 and rps11 , with gapdh showing the greatest stability, along with rpl8 , in the liver. Comparison of relative transcript abundance between tissues revealed that ghr demonstrated the highest expression in the liver, while gh demonstrated the highest expression in the spleen. Presented work characterizes genes with stable expression across various tench tissue types and identifies suitable reference genes for RTq-PCR for nutrient-related gene expression studies. Presented study was performed for tench for the first time and provides information on influence of poultry by-product meal on the tench organism. Information on tench genetic studies, especially combined with dietary treatments are sparse, therefore presented results address this gap and will bring attention of Aquaculture readers. [ABSTRACT FROM AUTHOR]

A paper which reviews the existing knowledge on tench in Sicily, Italy and explored the temporal changes of its distribution and outlined a programme of research conservation and management of tench in the island is presented. Topics covered include current knowledge on tench in Sicily, recommendations on the research plan for tench, and tench management prospects.

With the aim to evaluate different replacement levels of fish meal ( FM) by pea protein concentrate ( PPC) on survival, growth performance and body composition of juvenile tench ( Tinca tinca), a 90-day experiment was conducted with 6-month-old juveniles. Four practical diets (50% crude protein) differing in the level of replacement of FM protein by PPC protein were tested: 0% (control), 25%, 35% or 45%, corresponding to 0, 207.5, 290.4 or 373.3 g PPC kg−1 diet respectively. Survival rates ranged from 96.4% to 98.5%. The 25% and 35% replacement diets resulted in similar growth values ( P > 0.05) to those obtained with the control diet (average of the three feeding treatments: 57.57 mm total length, 2.48 g weight and 1.87% day−1 specific growth rate). The 45% replacement diet had the lowest growth ( P < 0.05). Fish with externally visible deformities ranged from 0% to 1.5%. The relation among amino acid profiles of the diets, body composition, growth performance of juveniles and amino acid requirements of other fish species is discussed. An amount of 290.4 g PPC kg−1 diet (35% replacement of FM protein) can be included in juvenile tench diets without impairing growth performance. [ABSTRACT FROM AUTHOR]

The diet composition of breeding Ospreys (Pandion haliaetus) was studied in several location in Latvia from 2009 to 2015 by determining food remains, intact or partly eaten fish in the nests, and photo and video materials from surveillance cameras that were set up at 14 nests. During the study period, information about 1501 Osprey prey specimens was collected from 119 nests and they were all fish. In total, 15 fish species were identified in Osprey diet, of which the most numerous was common carp (Cyprinus carpio), representing 47.2% of the diet, followed by tench (Tinca tinca) 14.3% and Prussian carp (Carassius gibelio) 11.3%, which was not found in studies conducted in other countries. The mean size of all mesured fish was 27.8 cm and corresponding weight was 368 g. Predatory fish (pike Esox lucius, perch Perca fluviatilis) represented only 4.7% of the whole diet. Osprey diet composition in Latvia showed that the population highly relies on fishponds. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate different replacement levels of fish meal ( FM) by poultry by-product meal ( PBM) on survival, growth performance and body composition of juvenile tench ( Tinca tinca). A 90-day experiment was conducted with 5 month-old juveniles (31.95 mm total length, 0.396 g weight). Eight practical diets (50% crude protein) differing in the level of replacement of FM protein by PMB protein were tested: 0% (control), 25%, 31%, 37%, 43%, 49%, 55% and 61% corresponding to 0, 184.8, 229.2, 273.5, 317.8, 362.1, 406.5 or 450.8 g PBM kg−1 diet respectively. Significant differences were not found ( P > 0.05) between 25% replacement of FM protein by PBM protein (184.8 g kg−1 PBM in diet) and control diet. At higher replacement levels, fish had significantly lower growth, higher feed conversion ratio and lower protein productive value ( P < 0.05). Fish with externally visible deformities ranged from 1.1% to 3.3%. The relation among amino acid profiles of the diets, body composition, growth performance of juveniles and amino acid requirements of other fish species is discussed. Up to 184.8 g PBM kg−1 diet can be included in diets for juvenile tench without impairing growth performance. [ABSTRACT FROM AUTHOR]