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Summary Aim of the study was to determine the effect of initial larval density on growth and survival of the common barbel Barbus barbus (L.) under controlled conditions. The experiment examined fish density from 20 to 200 ind. L−1 during intensive rearing at 25°C. Rearing lasted 21 days whereby the average total fish length, weight and survival were recorded. During the entire period fish were fed live nauplii Artemia sp. The data provided the basis for calculating the specific growth rate (SGR), Fulton's condition index ( K), and analysis of the relationship between biomass and the stocking density. The documentation was also used to determine the level of ontogeny. The study data obtained indicated that initial larval density has no effect on survival (over 98% in each treatment), level of ontogeny, or on the rearing indexes. Fish achieved the juvenile stage during the second week of rearing (<23 mm total length). At the end of the experiment fish reached 26.50-27.78 mm TL. SGR ranged from 22.75 to 23.53 (% day−1). No statistical differences were found among all treatments (P > 0.05). The findings of this study suggest that stocking density in common barbel larvae is not a factor limiting growth or the ontogenetic development rate during initial rearing. This creates considerable potential for improvement in stocking material production under controlled conditions and should have a positive effect on the economic effectiveness of production. [ABSTRACT FROM AUTHOR]

Concentrations of 10 metals (Al, As, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn) in muscle tissue of tench (Tinca tinca), water and sediment in Beysehir Lake were analysed using inductively coupled plasma atomic emission spectrophotometry (ICP-AES). Tench is one of the most abundant fish species in Beysehir Lake. Metal levels were analysed in only the muscle tissue of the fish, because this provides information on the potential risk to the fish themselves and to consumers of these edible portions of the fish. The Cu concentration was the highest in all the samples of the lake's sediments and waters, studied in all seasons, and ranged between 24.01 µg g-1 (in spring) and 90.30 µg g-1 (in summer), but Cu concentrations in T. tinca were low: 0.03 µg g-1(in summer) to 0.21 µg g-1(in spring). Metal concentrations in sediments, waters and tench varied seasonally. All metal concentrations in sediments were higher than those in water and fish. However, all metal concentrations, except Zn, were lowest in fish muscle tissue. [ABSTRACT FROM AUTHOR]

Abstract: The present study was designed to investigate the in vivo dose-response of mammalian GnRH analogue [d-Ala6, Pro9, NEthylamide]-mGnRH in stimulating a pre-ovulatory LH surge and subsequent ovulation in female tench. Five doses of mGnRHa (1, 2.5, 5, 10, and 20μg kg−1) and a control group (0.9% NaCl) were tested under hatchery conditions. Concentration of plasma LH and ovulation success were evaluated. All mGnRHa treatments yielded significantly higher LH levels and ovulation success compared to control. The only difference in LH levels was a higher level with 10μg kg−1 at 24h post-treatment. No differences were observed in ovulation success (≥60% of females) among mGnRHa treatments. However, non-linear regression analyses indicated increasing LH concentration and ovulation rate with increasing mGnRHa dosage. This trend implies that dosages in the range of 10–20μg kg−1 of mGnRHa can be considered reliable and effective concentrations. [Copyright &y& Elsevier]

The expression of anti-predator adaptations may vary on a spatial scale, favouring traits that are advantageous in a given predation regime. Besides, evolution of different developmental strategies depends to a large extent on the grain of the environment and may result in locally canalized adaptations or, alternatively, the evolution of phenotypic plasticity as different predation regimes may vary across habitats. We investigated the potential for predator-driven variability in shell morphology in a freshwater snail, Radix balthica, and whether found differences were a specialized ecotype adaptation or a result of phenotypic plasticity. Shell shape was quantified in snails from geographically separated pond populations with and without molluscivorous fish. Subsequently, in a common garden experiment we investigated reaction norms of snails from populations' with/without fish when exposed to chemical cues from tench (Tinca tinca), a molluscivorous fish. We found that snails from fish-free ponds had a narrow shell with a well developed spire, whereas snails that coexisted with fish had more rotund shells with a low spire, a shell morphology known to increase survival rate from shell-crushing predators. The common garden experiment mirrored the results from the field survey and showed that snails had similar reaction norms in response to chemical predator cues, i.e. the expression of shell shape was independent of population origin. Finally, we found significant differences for the trait means among populations, within each pond category (fish/fish free), suggesting a genetic component in the determination of shell morphology that has evolved independently across ponds. [ABSTRACT FROM AUTHOR]

Human-aided dispersal can result in phylogeographic patterns that do not reflect natural historical processes, particularly in species prone to intentional translocations by humans. Here, we use a multiple-gene sequencing approach to assess the effects of human-aided dispersal on phylogeography of the tench Tinca tinca, a widespread Eurasian freshwater fish with a long history in aquaculture. Spatial genetic analysis applied to sequence data from four unlinked loci and 67 geographic localities (38-382 gene copies per locus) defined two groups of populations that were little structured geographically but were significantly differentiated from each other, and it identified locations of major genetic breaks, which were concordant across genes and were driven by distributions of two phylogroups. This pattern most reasonably reflects isolation in two major glacial refugia and subsequent range expansions, with the Eastern and Western phylogroups remaining largely allopatric throughout the tench range. However, this phylogeographic variation was also present in all 17 cultured breeds studied, and some populations at the western edge of the native range contained the Eastern phylogroup. Thus, natural processes have played an important role in structuring tench populations, but human-aided dispersal has also contributed significantly, with the admixed genetic composition of cultured breeds most likely contributing to the introgression. [ABSTRACT FROM AUTHOR]

The study encompasses three reproduction seasons. Tench spawners caught during the spawning season originated from carp ponds (domestic stock) and a lake (wild stock). Fish were reproduced under controlled conditions after hormonal stimulation with GnRHa-containing pellets combined with metoclopramide (Ovopel) or carp pituitary homogenate (CPH). As a result of hormonal stimulation, eggs were obtained from a larger number of females originating from the lake (71.7%) than those originating from the pond (58.3%), although no other statistical differences were found. A similar relationship was recorded for the spermatozoa motilities (range from 72 to 76%). The obtained results indicate that both investigated reservoirs are suitable for tench broodstock management due to the fact that synchronization of ovulation among different stocks is easy to achieve. For this purpose, among the tested spawning agents, Ovopel could be recommended as being slightly more effective. [ABSTRACT FROM AUTHOR]

The suitability of defatted soybean meal as a substitute for fishmeal was assessed in juvenile (25 g, average) tench, Tinca tinca, by feeding them diets containing 25 (S25), 37.5 (S37.5) and 50% (S50) soybean meal for 150 days. Soybean meal inclusion increased the relationship between essential and non-essential amino acids. Fish were hand-fed to apparent satiation; the feed intake ratio was not dependent upon the dietary soybean level. Survival was over 95% and unaffected by treatment. Growth was reduced at higher soybean meal levels. After 150 days, average weight for the fish fed soybean diets S25, S37.5 and S50 was 65.6, 59.2 and 51 g, respectively. Growth performance was evaluated on the basis of specific growth rate (SGR), final biomass, feed conversion ratio (FCR), and feed intake (FI). Maximum SGR (0.61-0.64) and final biomass (3022-3156 g) were recorded in tench fed diets containing 25 and 37.5% soybean meal. Nutritional parameters such as feed intake and feed conversion ratio were not affected by the soybean meal. Body composition was similar for tench fed the three different diets. [ABSTRACT FROM AUTHOR]

Abstract: During an eight month study of the reproductive cycle in two age groups, and in both sexes, of tench (Tinca tinca L.), it was found that plasma concentrations of the presumptive ‘maturation inducing hormone (MIH)’ 17,20β-dihydroxypregn-4-en-3-one (17,20β-P) did not reach a peak during the spawning season, but as much as two months after spawning had ceased. The cessation of the spawning season was confirmed by histological examination of the gonads and by measurement of 11-ketotestosterone and 17β-estradiol in the plasma of males and females, respectively. Measurements were also made of the ‘alternative MIH’ 17,20β,21-trihydroxypregn-4-en-3-one in the older fish. However, this steroid did not show the same pattern as 17,20β-P. An assessment was made of the prevalence of primary spermatocytes in the testes of post-spawned fish – to test an alternative hypothesis that 17,20β-P might be involved in the stimulation of meiosis. However, there was no evidence for any increase in testis differentiation post-spawning. In fact the testes became increasingly undifferentiated as the autumn progressed. The role, if any, of this ‘unseasonal’ peak of 17,20β-P production remains to be determined. [Copyright &y& Elsevier]

The article focuses on flavobacterium psychrophilum which causes significant problems in aquaculture. Some of the diseases associated with the pathogen include rainbow trout fry syndrome (RTFS) and bacterial cold water disease (BCWD). The fish species which are particularly susceptible to the pathogen include rainbow trout and coho salmon. Some other fish species which reported diseases linked to the pathogen include eel, common carp, crucian carp and tench.

Abstract: Opisthorchiasis is a fish borne parasitic infection caused by helminths of the genus Opisthorchis (Digenea, Opisthorchiidae), affecting humans and other fish-eating mammals. Despite Opisthorchis felineus was first described in Italy in 1884, no cases of human opisthorchiasis were reported in this country until 2004; from then on, 4 outbreaks due to this species have been recorded in Central Italy. Following the more relevant of these outbreaks, involving 34 people in August 2007, snails, fishes and fecal samples collected from the Bolsena and Bracciano lakes (Central Italy) were analyzed in order to define the cycle of O. felineus in the area and investigate its prevalence in the different hosts. Pools of 20–40 snails each (4983 specimens altogether) of the genus Bithynia were analyzed by PCR for parasite DNA detection. Eight hundred and ninety-four fish belonging to 12 species were collected from the two lakes and tested for metacercariae both by muscle compression and digestion techniques. Eighty-seven fecal samples of 5 putative definitive host species were collected very close to the two lakes and tested for parasite eggs detection by formalin–ethyl acetate concentration technique. Identification at the species level of metacercariae and eggs, respectively, from fish and stool was confirmed by PCR analysis and sequencing. O. felineus DNA was detected in 0.08% (overall minimum infection rate) of snails of the genus Bithynia from the two lakes. The tench, Tinca tinca, was the only fish found infested in both lakes (prevalence 88.5%). O. felineus eggs were found only in cat feces (prevalence 46.4%). The tench represents the only threat for the human consumption in the study area while Coregonus sp., the most economically important species for the local fishery and frequently consumed raw marinated, resulted to be not infected. The high prevalence recorded both in fish and in definitive host suggests a widespread and massive presence of the parasite in the area. Further studies are needed to better investigate the possible role of some cyprinids species as intermediate hosts, in order to check their safety for human consumption. [Copyright &y& Elsevier]

The tench Tinca tinca is a valued table fish native to Europe and Asia, but which is now widely distributed in many temperate freshwater regions of the world as the result of human-mediated translocations. Fish are currently being transplanted between watersheds without concern for genetic similarity to wild populations or local adaptation, and efficient phylogeographic markers are therefore urgently needed to rapidly distinguish genetically distinct geographical populations and to assess their contribution to the hatchery breeds and to the stocked wild populations. Here, we present a new method to distinguish recently discovered and morphologically undistinguishable Western and Eastern phylogroups of the tench. The method relies on PCR-RFLP assays of two independent nuclear-encoded exon-primed intron-crossing (EPIC) markers and of one mitochondrial DNA (mDNA) marker and allows the rapid identification of the Western and Eastern phylogroup and also of three geographical mtDNA clades within the Eastern phylogroup. Our method will enable researchers and fishery practitioners to rapidly distinguish genetically divergent geographical populations of the tench and will be useful for monitoring the introduction and human-mediated spread of the phylogroups in wild populations, for characterization of cultured strains and in breeding experiments. [ABSTRACT FROM AUTHOR]

Although tench (Tinca tinca Linnaeus 1758) has been cultured traditionally in Eurasia, Central and Southern Europe mostly by low intensity methods, investigations of the optimum intensive culture conditions for the species have recently been initiated. This work was aimed to investigate the effect of food ration level on growth and survival of sub-adult tench, under intensive culture conditions. One hundred and twenty individuals (24.55 g ± 3.28) were fed for 102 days at three feeding levels: 0.5%, 1%, 2% b.w.d-1. Higher body weights (b.w.) have been achieved with the 2% ration level in all experimental phases. However, by the end of the experiment (up to the b.w. of 34 g), fish fed with the ration level of 1% b.w.d-1 resulted in better indices (FCR, SGR, % weight gain). These findings conform to the ones previously observed for tench juveniles and indicate that the 1% b.w.d-1 ration level (below satiation) could be advantageous for tench sub-adults as well. [ABSTRACT FROM AUTHOR]

The aim of the study was to evaluate the use of laparoscopy for the assessment of the reproductive tract and stage of gonadal development of the tench ( Tinca tinca). Laparoscopy was carried out from February to March 2009, on 30 anesthetized tenchs, 15 males and 15 females, of approximately 250 g bodyweight and 30 cm length, using a 1.9-mm rigid cystoscope. Male and female gonads, attached to the swim bladder, were visualized. Testes were orange with a striped appearance. Mature ovaries were cluster-shaped and whitish. Histological samples were collected, from the reproductive organs of both the sexes, with a forceps and showed the presence of gametes at different stages of maturity. The application of this minimally invasive diagnostic imaging technique could clinically be used as a powerful tool to evaluate the gender and to establish the reproductive status of tench and other fish. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate whether the enzyme-linked immunosorbent assay (ELISA) anti-Adda technique could be used to monitor free microcystins (MCs) in biological samples from fish naturally exposed to toxic cyanobacteria by using receiver operating characteristic (ROC) curve software to establish an optimal cut-off value for MCs. The cut-off value determined by ROC curve analysis in tench ( Tinca tinca) exposed to MCs under laboratory conditions by ROC curve analysis was 5.90-μg MCs/kg tissue dry weight (d.w.) with a sensitivity of 93.3%. This value was applied in fish samples from natural ponds (Extremadura, Spain) in order to asses its potential MCs bioaccumulation by classifying samples as either true positive (TP), false positive (FP), true negative (TN), or false negative (FN). In this work, it has been demonstrated that toxic cyanobacteria, mainly Microcystis aeruginosa, Aphanizomenon issatchenkoi, and Anabaena spiroides, were present in two of these ponds, Barruecos de Abajo (BDown) and Barruecos de Arriba (BUp). The MCs levels were detected in waters from both ponds with an anti-MC-LR ELISA immunoassay and were of similar values (between 3.8-6.5-μg MC-LR equivalent/L in BDown pond and 4.8-6.0-μg MC-LR equivalent/L in BUp). The MCs cut-off values were applied in livers from fish collected from these two ponds using the ELISA anti-Adda technique. A total of 83% of samples from BDown pond and only 42% from BUp were TP with values of free MCs higher than 8.8-μg MCs/kg tissue (d.w.). © 2009 Wiley Periodicals, Inc. Environ Toxicol 26: 45-56, 2011. [ABSTRACT FROM AUTHOR]

Abstract: Studies of the growth hormone (GH) gene have both fundamental and practical significance, but no data on intra-specific polymorphisms of the tench, Tinca tinca, GH gene has been available. In the present study, the complete GH gene was cloned from 17 tench individuals chosen from 10 European and two Asian populations, cultured as well as wild and sequenced from 28 recombinant plasmids (at least one per individual). The tench GH gene was found to be 1758–1763bp in length. Altogether 14 polymorphic sites were observed, 12 located in introns (SNPs and very short indels) and two in exons (SNPs only). In non-coding regions, the highest polymorphism was found in intron 2 (five SNPs and two indels). Intron 4 was short (137bp) and monomorphic. In coding regions, one polymorphic site was observed in exon 3 and one in exon 5. The detected SNPs in exons were synonymous, having no effect on the amino acid composition of the GH protein. Thirteen GH gene haplotypes were observed. The tench GH gene haplotypes clustered into two major classes with a mean genetic distance of 0.0037±0.0014 and coefficient of GH gene differentiation of 0.67±0.129 (mean±S.E.). The two classes corresponded, based on phylogroup-specific PCR-RFLP, with previously determined two phylogroups, western and eastern. Although the described tench GH gene haplotypes might not include all the existing ones, all common polymorphic sites were identified. Polymorphisms in the tench GH gene, a representative of the five-exon type, are not as extensive as in fishes with the six-exon GH gene. However, GH gene polymorphisms in tench can still serve as suitable markers for population studies and conservation purposes. Investigation of growth performance differences in fish of different GH gene classes and/or haplotypes may be valuable. [Copyright &y& Elsevier]

In the current paper we present a method of rearing tench (Tinca tinca L.) larvae under controlled conditions, fed on dry food (Gemma and Perla) and Artemia nauplii or decapsulated cysts of Artemia. Tench larvae were obtained after artificial spawning by aid of Ovopel stimulation. Two experiments were conducted during which fish were divided into 4 groups (in duplicate) and placed in 30 dm3 glass fish tanks set up in a recirculating system. The fish were fed ad libitum and reared for 25 days. Larvae were fed exclusively (experiment 1) or after 10 days (experiment 2) of receiving Artemia nauplii with two types of compound feeds and decapsulated cysts of Artemia. The best growth rate was observed in the control group fed on Artemia nauplii and in the group offered decapsulated cysts in both experiments. The highest survival rate, over 96%, occurred in the control group. A twofold worse survival rate was obtained in the group fed exclusively on dry food. Applied transition schedule had significant effect on survival rate among treatments, however it did not influence the percentage of body deformations occurring in groups receiving compound feed only. The results obtained indicate the necessity of applying gradual transition from live food to compound feed and the improvement of feeding schedules in common tench culture. [ABSTRACT FROM AUTHOR]

Abstract: In this study, the chronic effect of the insecticides carbofuran and deltamethrin on acetylcholinesterase (AChE) activity and malondialdehyde (MDA) and reduced glutathione (GSH) levels were examined in the brain of tench. Both pesticides were evaluated in two separate experiments, and animals were exposed in a continuous flow-system to three different concentrations of carbofuran (0, 10 and 100μg/L) and deltamethrin (0, 0.0039 and 0.039μg/L) for 60days. After that period, animals were kept into pesticide-free water for other 30days. In all cases, animals were sampled every 10days all along the experience. AChE activity was significantly inhibited in fish exposed to 100μg/L of carbofuran, during the first 30days of exposition, returning to basal levels after this initial period. With respect to deltamethrin exposure, AChE activity was not significantly affected. When considering MDA levels, significant changes could only be detected during the recovery period for both pesticides, with a maximum of induction at 70 and 80days, respectively associated to the highest dose of carbofuran and deltamethrin. Similarly, GSH levels varied all along the experience, with a maximum of significant increase at day 80 of exposition to the highest dose of both pesticides. This study shows that changes in AChE brain activity in tench can be used as a biomarker of early pesticide exposition in environmental monitoring programs, whereas MDA and GSH levels could be more associated to long-term expositions. The above results confirm and broaden former observations, suggesting that more investigations are needed before these biochemical parameters can be used as biomarkers. [ABSTRACT FROM AUTHOR]

The article discusses a study which examined the potential changes in the number of total and psychotrophic microorganisms in the fillet of skinned and skinnless tench fish. The study used three different ways and cold-storage to treat the fish for coliform, Escherichia coli, Staphylococcus aureus, Salmonella spp. and Listeria spp. The results showed that freezing and storing procedures failed to destroy the microorganisms totally. The study suggested to apply the glaze method after treating fish skinnless.

triennial performance test of five groups of tench, Tinca tinca (L .): Vodnany induced triploid V3n, Vodnany meiotic gynogenic Vgyn, diploid Vodnany V2n, Hungarian H2n and German G2n) in pond monoculture was carried out with diploid golden tench as control (C) to compute corrected weight of the groups tested. Survival rate ranged from 11.6% (V2n) to 30.6% (Vgyn) in yearlings, from 71.2% (V2n) to 91.5% (H2n) in 2 year-olds, from 60.0% (Vgyn) to 75.7% (V2n) in 3 year-olds while that of the control group was 8.5, 38.3 and 40.2% in the respective seasons. After three growing seasons the corrected weight of the fish in the groups H2n (254.6g), V3n (257.0g) and G2n (371.4g) was higher ( P < 0.05, Tukey HSD test) than that from the C (183.3g) and V2n(205.6g) groups. Among the chromosomally manipulated groups, ANCOVA test found the least slaughtering value for Vgyn (84.3%); among the purebreds the highest value was found for H2n (87.32%), significantly differing from V2n and G2n strains. A high gonadosomatic index in females (2.94 vs. 0.44% in males) resulted in inferior slaughtering values. [ABSTRACT FROM AUTHOR]

Tinca tinca were sampled seasonally from Lake Trasimeno in order to investigate the influence of heavy metal accumulation and changing environmental parameters on the antioxidant responses in this species. Liver, gills and kidney of both sexes were analyzed for total glutathione, catalase, glutathione peroxidase, glutathione reductase, glutathione S-transferase, glyoxalase I, glyoxalase II, while muscle was analyzed for arsenic, lead, cadmium and mercury. The MRLs (maximum residue limits) set by actual regulation were not exceeded for heavy metals, but a seasonal and sex-linked variability of antioxidant parameters was observed, and major variations occurred especially in summer and autumn. In this shallow lake, heavy metal accumulation did not affect the biochemical variations, which are rather due to the decreased water level inducing hyperoxia and hypoxia within 24 h, high temperature and loss of mating and refuge areas. [ABSTRACT FROM AUTHOR]

Groups of juvenile tench (7.02 ± 0.28 g) were reared under four different light regimes; blue light, red light (80 Wm 12L:12D photoperiod) white light (912 ± 210 lux, 80 Wm, 12L:12D photoperiod) and no light (0 lux) (0L:24D). Visibility of fish out of shelters was used as an indicator of activity and was monitored by video recording. Blood plasma cortisol concentrations were also measured. Fish under blue or white light were significantly less active during the photophase than those under red or no light ( P < 0.01). Red light produced similar activity patterns to fish receiving 24 h darkness. Plasma cortisol concentrations were also significantly influenced ( P < 0.05) with the fish under white light having the highest plasma cortisol concentration (317 ± 62 ng cm) compared to fish in the dark treatment (106 ± 36 ng cm). Thus, the provision of coloured light filters increases activity in juvenile tench and may reduce their intrinsic stress level. [ABSTRACT FROM AUTHOR]

One hundred and thirty-two tench were photographed and a total of 13 landmarks were identified. Fish were grouped in four size classes on length basis and different shape descriptors were computed. Landmark configurations were superimposed. Size was computed as centroid size. The roundness coefficient, the log(partial area)/log(total area) ratio and the condition coefficient were calculated. Slaughtering performances and fillet composition analyses were performed. Shape variability was found primarily on cephalic area while head and tail regions were more homogeneous. A high correlation between centroid size and total length was found as well as a higher increase of the partial area than the total area justifying the hump shape of this tench. The scatter of relative warp 1 scores and centroid size for the four size classes has showed, with the increase of the length, a larger number of specimens that were characterised by a deep profile. Geometric morphometric approach produced a valuable tool in defining morphospaces for tench. Condition coefficient ranged from 1.24 to 1.29, without any significant difference among the size classes. Slaughtering performance resulted in agreement with those reported by other authors while VSI was lower. In fillets, the fatty acid profile was composed of about 30% of saturated fatty acids, 50% of monounsaturated fatty acids and 20% of polyunsaturated fatty acids with about 8% of docosahexaenoic acid. Atherogenic and thrombogenic indices were 0.58 and 0.42, respectively. Both n6/n3 and polyunsaturated/saturated fatty acids ratios were in accordance with value recommended for a healthy nutrition giving positive evaluation of the nutritional qualities of tench. [ABSTRACT FROM AUTHOR]

Juvenile tench, Tinca tinca (L.) (initial mean weight 0.67 g) were continuously fed at high (5.0% of fish biomass) or low (2.5% of fish biomass) daily doses of a commercial formulated diet, or starved for 6 days, then fed these doses. The experiment lasted 40 days. Visible skeletal deformities occurred in fish fed the high doses, and the 6-day food deprivation mitigated the percentage of deformed fish from 37.3 to 12.1%. Deformities were associated with higher condition coefficient value. Faster growing individuals were more susceptible to body malformations within the feeding groups. No compensatory growth in body weight was observed in juveniles fed high or low doses. Lack of compensation was supported by lower carbon/nitrogen ratio in starved-re-alimented fish. Morphometric indices (condition coefficient and height/length ratio) suggested only partial compensation observed mostly during the first few days after the end of starvation. The possible mechanisms underlying this weak compensatory response in T. tinca juveniles may be associated with their slow growth rate and low oxygen consumption. Short starvation mitigates body deformities in intensively fed tench juveniles, however, this technique is not recommended in aquaculture due to their weak compensatory growth response. [ABSTRACT FROM AUTHOR]

The influence of dose and time of eggs exposure in tannin solution on tench embryonic development, survival of embryos and percentage of larvae hatched were studied. The eggs obtained under controlled conditions from 11 tench females were fertilized with semen from 7 males and then rinsed for 1 h in Woynarovich solution (40 g urea, 30 g NaCl per 10 dm of water). Random samples (50 cm) of the fertilised eggs were placed into three tannin solutions 0.05, 0.1 or 0.15% for 30, 60 or 90 s, then they were transferred to Weiss jars where incubation at 25°C took place. Tannin solution of 0.05% for 30–90 s or 0.1% for 30 s allowed effective unsticking of eggs and resulted in a very high per cent of hatched larvae. Extending the eggs rinsing time to 60 s in 0.10 and 0.15% solutions resulted in a high mortality of embryos during hatching because of hardened egg capsule. [ABSTRACT FROM AUTHOR]

The effect of keeping female tench in two different types of keepnets for 24 h after landing was tested. The first type, fine knotted nylon mesh, was placed in two different positions in the edge: (a) anglers position, anchored on one side and (b) stretch position, anchored on both ends of the keepnets. The second type was made of dense fine and soft textile net in black color and anchored on both ends in a stretch position. After capture by rod the fish were landed by hand, the hook was removed and the damage to the body and fins checked before confining the fish inside the keepnets. After confinement, blood samples were collected and the number, disposition and extent of wounds checked. The retention in the keepnets did not produce significant changes in plasma cortisol, glucose and osmolality. Fine knotted nets caused more injuries than the soft textile one. As a consequence, the use of this latter type is recommended for tench retention. [ABSTRACT FROM AUTHOR]

Nine species-specific microsatellites were used to characterize 792 tench, Tinca tinca (L.), from 21 wild and cultured populations. Seven loci were polymorphic expressing four to 22 alleles. A Spanish cultured strain was homozygous at all loci for all individuals studied. Low variability was also observed in a wild population from Sapanca Lake, Turkey and a Chinese cultured strain. In contrast, the highest variabilities were found in wild tench from lake Felchowsee (average number of alleles), and the cultured strain from Königswartha (average heterozygosity), both from Germany. Genetic differentiation between populations was moderate to high. The smallest genetic distances were found between the geographically most distant populations. A Neighbor-Joining tree showed only two major clades consisting of 4 and 17 populations, respectively. Within the smaller clade the Turkish wild and Spanish and Chinese cultured tench formed a sub-cluster with 100% bootstrap support. Possible reasons for the latter unexpected grouping are discussed. [ABSTRACT FROM AUTHOR]

Performance and physiological traits and health of spontaneous and induced triploid tench are reviewed. Triploidy is best induced with cold shock; with triploids exhibiting 13.5–51.5% better weight gain, 2.69–3.94% higher slaughtering value, 20–60% lower gonadosomatic index, 0.9–4.5% higher dry matter in flesh and up to 107% more flesh fat than diploids, if farmed untill post sexual maturity. Triploids exhibit more abdominal fat and less polyunsaturated fatty acids of the n-3 and n-6 groups in the flesh. Triploid females are sterile, while triploid males may produce aneuploid spermatozoa with varying DNA content (1–1.9n) which may initiate development of embryos. Triploids have milder seasonal dynamics in their erythrocyte profile than the diploids. Thinner diffusion distance in gills of triploids than in diploids is interpreted as adaptation to lower aerobic capacity. Triploids show neither stronger tendencies to anatomic malformations, nor have bigger affinity to parasitic diseases than the diploids. Production of triploid tench could be an economically interesting method of farming to higher marketable weight, bringing a relatively high product quality. [ABSTRACT FROM AUTHOR]

Influence of beta-1.3/1.6-glucan (Macrogard) on the innate immunity and protection against Aeromonas hydrophila in tench ( Tinca tinca (L.)) was assessed. Macrogard was fed at doses of 0, 0.5, 1 and 2 g kg of pellets for 1 month. The blood, spleen and head kidney from 10 fish of each group were separated and analysed for immunity parameters. Twenty tench from each group were infected with A. hydrophila. Macrogard at doses 1 and 2 g kg of feed significantly ( P < 0.05) increased the phagocytic activity of macrophages and proliferative response of mitogens stimulated lymphocytes. The same doses significantly ( P < 0.05) increased lysozyme activity and Ig level in serum, compared to the control and dose 0.5 g kg of feed. The challenge test showed that Macrogard reduced mortality of tench after experimental infection (5–35%). [ABSTRACT FROM AUTHOR]

The ultrastructure of diploid and triploid tench Tinca tinca (L.) spermatozoa were examined using electron microscopy focusing on parameters that influence movement. Triploid tench were produced artificially using a cold shock. Spermatozoa of triploid males in comparison with diploids featured significantly larger head ( P < 0.01), higher amount of mitochondria ( P < 0.05), and, surprisingly larger widths of the peripheral doublets and central pair of microtubules and the single microtubule ( P < 0.01). However, the diameters of the flagellum were without significant differences as well as the length of the flagellum and length and width of the midpiece. Also motility parameters of spermatozoa did not significantly differ between diploid and triploid males, but the total velocity (summary of spermatozoa velocity and duration of movement) positively correlated with the flagellum length and negatively with the head diameter of tench spermatozoa with a high significant influence ( P < 0.01). [ABSTRACT FROM AUTHOR]

The Eurasian range of the tench distribution is subdivided into deeply divergent Western and Eastern phylogroups evidenced by nuclear and mitochondrial DNA sequence markers. A broad zone of overlap exists in central and western Europe, suggesting post-glacial contact with limited hybridisation. We conducted a population genetic test of this indication that the two phylogroups may represent distinct species. We analysed variation at introns of nuclear genes, microsatellites, allozymes and mitochondrial DNA in populations from two postglacial lakes within the contact zone in Germany. The test is based on the expectation that in the presence of strong barriers to reproduction, a hybrid population will show genome-wide associations among alleles and genotypes from each phylogroup even after hundreds of generations of interbreeding. In contrast to this expectation, no consistent significant deviations from linkage and Hardy–Weinberg equilibria were found. Samples from both lakes did show significant disequilibria but they were limited to individual loci and were not concordant between populations, and were not robust to the method used. The single consistent association can be attributed to physical linkage between two microsatellite loci. Thus, results of our study support the hypothesis of free interbreeding between the two phylogroups of tench. Therefore, although the phylogroups may be considered as separate phylogenetic species, the present data suggest that they are a single species under the biological species concept. [ABSTRACT FROM AUTHOR]

The effects of Diazinon 60 EC (organophosphate insecticide, active substance diazinon) on mortality, growth rate, early ontogenetic rate, and occurrence of malformations was studied in embryos and larvae of tench, Tinca tinca (L.). The exposure of fish to 0, 10, 100, 1,000, and 3,000 μg dm of Diazinon 60 EC was initiated 24 h after fertilization of eggs and concluded 32 days later. At the highest concentration tested (3,000 μg dm), total mortality was observed within the first 15 days of exposure. A concentration of 1,000 μg dm caused high incidence of malformations, decrease in growth rate and ontogenetic development slowed down. A concentration of 100 μg dm mildly decreased growth rate, but at 10 μg dm no changes compared to the control were observed. Thus, Diazion 60 EC at the concentration of 10 μg dm is not dangerous for the embryos and larvae of tench. [ABSTRACT FROM AUTHOR]

Two trials of the performance (growth, survival, dress out) of a number of different tench breeds/groups were conducted to elucidate the implications for the establishment of a coordinated breeding program. The first trial with a top-crossing scheme had to be concluded after 1st wintering. Age 1 + hybrids of Romanian-R breed with Tabor-T, Vodnany-V and Hungarian-H breeds displayed significantly better performance in weight and/or survival when compared to pure Romanian population (e.g., weight in R × T = 27.7 ± 11.1 g vs. R × R = 21.9 ± 8.6 g; or survival in R × V = 92.3% vs. R × R = 47.7%). The second trial with Czech breeds (Vodnany-V; Hluboka-HL; Velke Mezirici-VM and Tabor-T) revealed a very good growth in Hluboka breed. Weight of HL breed compared to Vodnany breed, representing the lowest growth, was 95.7, 103.3, and 40.5% higher after the 2nd growing season, the 2nd wintering and the 3rd growing season, respectively. Performance in survival and dress out at market size differed significantly between breeds as well, even if not corresponding always with growth performance. In conclusion the establishment of a coordinated breeding program, taking into account the origin of tench, might be useful tool for the improvement of tench production. [ABSTRACT FROM AUTHOR]

Triploidy interferes with gametogenesis in all fish species tested so far. In fish it results in complete female sterility however, males are still able to develop testis. The reason why sterility levels in triploid fishes differ among species and between sexes is unclear. In the present study the reproductive capacity of triploid males of tench was studied. Flow cytometry revealed sperm cells of triploids to be largely aneuploid with high mosaic DNA, oscillating from haploid DNA to diploid DNA content. Analysis of variance showed an insignificant influence of ploidy level on the percentage of motile spermatozoa, as well as on spermatozoa velocity. Experimental crosses between normal diploid female and triploid males resulted in the appearance of triploid progeny, which exhibited genotypes composed of microsatellite alleles inherited from the founder female and additional allele derived from the donor male. We can conclude that the triploid males analysed in the present study were capable to fertilize eggs derived from diploid females. [ABSTRACT FROM AUTHOR]

Juvenile tench (initial weight of about 57 g) were fed feed supplemented with fish oil (group FO), linseed oil (group LO), peanut oil (group PO), or rapeseed oil (group RO) containing 47% protein and 12% fat for 55 days. The inclusion of the tested oils was 50 g kg (42% total crude lipids in diets). No significant differences were noted in the fish growth performance. The proximate composition of the whole fish bodies and the viscera (water, protein, fat, ash) was similar in all the dietary treatments ( P > 0.05). Differences were noted only with regard to the ash content of the fillets ( P < 0.05). The analysis of the fatty acids profiles of tench (whole fish) indicated there were significant differences in the total content of monoenoic and polyenoic (PUFA) acids. Significant differences were also noted with regard to n-3 PUFA and n-6 PUFA. Consequently, the ratio of n-3/n-6 acids ranged from 1.6 (group PO) to 2.08 (group LO; P < 0.05). The feed applied was not confirmed to have had an impact on the fatty acids profile of the tench fillets. There was a statistically significant intergroup difference in the content of saturated fatty acids (SFA) in tench viscera. In the fish fed vegetable oils supplemented diets, the level of SFA was lower ( P < 0.05). [ABSTRACT FROM AUTHOR]

first attempt to introduce tench ( Tinca tinca (L.)) to Israel, followed by comparative growth experiments, was carried out in 1947. A batch of 200 fingerlings, which were supposed to serve later as brood fish, was imported from Switzerland to Fish Culture Experimental Station at Sdeh Nahum. However, after 2 years tench were considered unsuitable for culturing in Israel and the trials were abandoned. Two factors affected negatively these historically early trials: (1) Tench was just second exotic species introduced to Israel some years after introduction of the common carp, and the Israeli fish farming expertise at that time was low. (2) The Independence War temporarily delayed advancement of aquaculture. A second introduction of tench was performed in 1992, when a golden mutant of tench was imported to Gan Shmuel Fish Breeding Center (GS-FBC) from the Research Institute of Fish Culture and Hydrobiology at Vodňany, Czech Republic. Currently, GS-FBC is the only Israeli fish hatchery that maintains golden tench as a part of breeding program as well as a number of other varieties of ornamental fish and species, all of them produced mostly for export. Tench (800–1,000 g) females are maintained separately from males, in order to prevent uncontrolled reproduction. Routinely, in April, the fish are transferred indoors and induced to spawn artificially with a single injection of GnRH synthetic analog— DAGIN. Dry method of stripping is used to obtain eggs and sperm. After fertilization the sticky eggs are spread in a single layer on walls of 230 dm cylindrical incubators provided with conical bottom, or they are degummed using a solution of milk/water. At a water temperature of 24°C, hatching (70% hatching rate) occurs 36–40 h after fertilization. The larvae absorb their yolk sac 2–3 days after fertilization and they start feeding on small size (200 μm) Artemia nauplii. At the age of 7–10 days, if fry are retained indoors, they are fed with regular size Artemia and starter feed, or are released into a nursing 0.5–1.0 ha pond. Usually, the fish are grown to the marketing size (5–15 cm) and exported abroad, mainly to Europe. About 100,000 golden tench fingerlings, with a total value of € 40,000 are produced and marketed annually. [ABSTRACT FROM AUTHOR]

the onset of swimbladder inflation, Tinca tinca larvae were exposed for 24 h to cadmium or copper at 0.0 (control concentration), 0.1, 0.2 and 0.3 mg dm at 22°C. From then larvae were reared at 25°C for 9 days in un-supplemented water. Both metals resulted in a significantly reduced growth, survival, and retarded swimbladder inflation in a dose-response manner. The highest Cd and Cu concentration delayed the onset of exogenous feeding (live artemia nauplii) for 2 or 1 days, respectively, comparing to the control concentration. Our results demonstrate a highly toxic effect of Cd and Cu in the studied period of larval ontogeny, when fish seem especially sensitive. Although, at low concentrations and long exposure period, Cu is considered more toxic to fish than Cd, our study revealed the reverse effect for first-feeding larvae of both metals at high concentrations and short exposure. [ABSTRACT FROM AUTHOR]

The study investigated the age, growth and sex ratio of Tinca tinca L., 1758 in Seyhan Dam Lake, Turkey and determined its first population structure data in the lake. Fishermen had introduced tinca into the lake between 2001 and 2002. A total of 1284 T. tinca (778 males and 506 females) were captured between January and December 2007 by gill nets of various mesh sizes. The sex ratio was 1 : 1.53 females to males. Total lengths and weights ranged from 12 to 29 cm and 27 to 403.3 g. Ages in both sexes ranged from 1 to 5 years. For all individuals the length-weight relation and von Bertalanffy growth parameters were W = 0.063 × L2.51 ( r = 0.981), and L ∞ = 50.86 cm, k = 0.112 year−1, to = −1.551 year. [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. [ABSTRACT FROM AUTHOR]

Polymorphism was detected at ND1, ND6, D-loop and cyt b segments of mtDNA in 105 tench ( Tinca tinca L.), using the polymerase chain reaction–restriction fragment length polymorphism (PCR–RFLP) technique and five composite haplotypes were identified. The diversity indices and the results of the population comparisons revealed that the identified markers provide a powerful tool for further studies on this species. [ABSTRACT FROM AUTHOR]

There are no specifically formulated dry foods for tench (Tinca tinca L.), which forces farmers to use diets formulated for other fish species. This has major drawbacks, such as high mortality, slow growth, and body deformities. A 120 day experiment was performed with five-month-old juvenile tench (initial mean weight: 0.388 g; total length: 31.78 mm) to evaluate decapsulated Artemia cysts as a supplement to a dry diet for other fish species. Three treatments, differing in the daily supplement, were tested: 1,800 freshly hatched nauplii, 1,800 cysts, and 300 cysts per g of tench biomass. Final survival ranged between 95.3% and 97.9%. Juvenile tench that received the supplement of 1,800 decapsulated Artemia cysts had a specific growth rate (1.28), weight (1.83 g), and total length (52.30 mm) significantly higher than those with the same amount of nauplii. The lowest supplement (300 cysts/g of fish biomass) allowed significantly lower growth and higher condition coefficient (1.40) than the rest. Animals with body deformities (1.06%) were only recorded in the groups that received the lowest cyst supplement. Results showed Artemia cysts are a suitable dietary supplement for juvenile tench, being an advantageous alternative to live nauplii. [ABSTRACT FROM AUTHOR]

Exogenous steroids alter sex differentiation in fish substantially. In the present study we have evaluated the effects of 17α-methyltestosterone (MT) and oestrogen receptor antagonist Tamoxifen (TA) on gonadal development and skewness of the sex ratio in all-female tench juveniles. In the first two experiments, sexually undifferentiated juveniles were orally treated with three doses of MT and TA (50, 100 and 150 mg kg−1). Both the treatments resulted in a moderate dose-dependent masculinization, with neomale production ranging from 17% (50 mg kg−1) to 26% (150 mg kg−1) for the MT only treatment, and from 0% (50 mg kg−1) to 27% (100 mg kg−1) only for the TA treatment respectively. In the third experiment treatment of sexually differentiated tench females with single steroid treatments or combinations of the two resulted in populations composed of females and intersex individuals. The significantly highest occurrence of intersex individuals (45.5%) was found in the group subjected to combine treatment of MT+TA (150+200 mg kg−1). No masculinization effect of the single or the combined treatment occurred. It can be concluded that oral treatment with MT or TA only slightly modifies the normal process of sex differentiation in gynogenetic tench juvenile, but treatment with the above-mentioned combinations has a highly significant potential to skew the sex ratio in sexually differentiated tench females. However, from an applied point of view, the treatment procedure will need optimization before use at a commercial level. [ABSTRACT FROM AUTHOR]

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The way in which an organism responds behaviourally to environmental stimuli may either be innate (i.e. expressed without the need for previous experience) or affected by prior experience; but the relative importance of these two mechanisms in controlling antipredator behaviour is, as yet, unclear. We investigated how the avoidance behaviour of juvenile great pond snails, Lymnaea stagnalis (L.), artificially selected for either high or low innate avoidance behaviour, where the snail crawls above the waterline in response to predation cues, differed in terms of their response to prolonged exposure to predator kairomones during their development. Specifically, we tested: (1) whether snails from lines selected for low response showed enhanced crawl-out behaviour following exposure to predator kairomones during development; and (2) whether snails from high-response lines were able to increase their response further when raised in predator kairomone or whether these snails were constrained in their response. Following developmental exposure to kairomones from a predatory fish (i.e. tench, Tinca tinca L.), low-response snails showed an increased avoidance response when exposed to predation (i.e. predator kairomone plus alarm cues), equivalent to that seen in lines selected for high innate responses. In contrast, snails from high-response selection lines showed no change in crawl-out behaviour. These findings suggest that for antipredator behaviour, developmental exposure can compensate for the selected reduction in innate response in L. stagnalis, and that there may be constraints limiting the maximum level of crawl-out behaviour. [Copyright &y& Elsevier]

The quality control of marinated tench with sauce stored at 4 °C was investigated in terms of sensory, chemical (total volatile basic nitrogen (TVB-N), trimethylamine (TMA), thiobarbituric values (TBA), peroxide value, free fatty acids, biogenic amines, fatty acids, and pH and microbiological parameters (total aerobic count, coliform, Escherichia coli, and Salmonella) during 6 months of storage. The use of alcohol vinegar and salt in marinated tench caused the TVB-N, TMA to decrease. The maximum TVB-N and TMA values were found to be 12.77 mg/100 g and 4.68 mg/100 g after 150 days and 180 days storage period, respectively. Oxidative rancidity in marinated tench was found to be low (2.81 mg MA/kg) and rancid flavor was not detected even after a storage period of 180 days. As storage time progressed, putrescine, cadaverine, and serotonine became the dominant amines. Salmonella, coliform, E. coli, and Staphylococcus aureus were not detected during the storage period of 6 months. Total bacteria count increased to 4.3 log CFU/g at the end of the storage period. Data obtained from this study showed that marinated tench can be stored for more than 6 months. [ABSTRACT FROM AUTHOR]

Abstract: Here we present a detailed study of the major events in the retinal histogenesis in a freshwater epibenthonic fish species, the Tench (Tinca tinca, Linneo 1758) during embryonic, prolarval, larval, and juvenile stages, using classical histological and immunohistological methods, providing a complete neurochemical characterization of retinal cells. We find a morphologically undifferentiated retina during embryonic stages and even at the hatching stage (postnatal day 0, P0). However, the emergence of the different retinal layers occurs in the first postnatal day (P1). Proliferating PCNA-positive cells are found in the retina of all postnatal individuals included in the present study, located in the circumferential germinal zone (CGZ), and in sparse cells dispersed throughout the inner nuclear layer (INL) and the outer nuclear layer (ONL). All neurochemical markers used start to express between P0 and P2. Anti-opsin, -α-protein kinase C, -α-tyrosine hydroxylase, -glutamine synthetase antibodies stain selectively different subpopulations of photoreceptor, bipolar, amacrine, and Müller cells respectively. Parvalbumin immunoreactivity is detected in amacrine and displaced amacrine cells. Several subpopulations of calretinin-positive ganglion, amacrine, and bipolar cells are detected in tench retina. Islet1 expression is confined to the nuclei of subpopulations of ganglion, amacrine, bipolar, and horizontal cells. All the maturational events described are first detected in the central retina and, as development progresses, they spread to the rest of the retina following a central-to-peripheral gradient. Therefore, tench postnatal retinal differentiation is a remarkable process not observed in the more common models of teleosts used in developmental biology. [Copyright &y& Elsevier]

Contents Vitrification could provide a promising tool for the cryopreservation of fish embryos. However, to achieve cryopreservation using vitrification, chilling sensitivity and cryoprotectants toxicity were determined using tench embryos at four developmental stages (11, 17, 23 and 29 h). Embryos treated with alcalase (2 ml/998 ml, 2 min at 22°C) were exposed to chilling with/without warming. Other embryos were exposed to methanol and glycerol at the concentration of 10% and 20% for periods of 20 min. At last, embryos were incubated at special incubator cages where hatching rates were counted. Regarding chilling sensitivity and exposure to chilling followed by warming, the hatching rates of embryos decreased significantly (p < 0.001) after exposure to 0°C at all developmental stages except the 29-h stage compared with the controls. The embryo stage most sensitive to chilling was 11-h stage. The 29-h stage exhibited the least sensitivity to low temperature while 17-h and 23-h stages were intermediate in their sensitivity to chilling. The toxicity of methanol increased significantly (p < 0.001) with developmental stage for 11, 17 and 23-h stages. The highest hatching rates of tench embryos were obtained with 29-h embryos using various concentrations of methanol. The hatching rates of tench embryos exposed to glycerol concentrations were approximately similar to those embryos exposed to methanol concentrations except for 11-h embryos that showed no hatching. Unfortunately, we could not obtain living embryos in any of the conditions examined after vitrification. In conclusion, it was quite difficult to vitrify the tench embryos during this study using various vitrifying solutions and the method reported by Chen & Tian (2005) and further studies are needed to achieve successful cryopreservation. [ABSTRACT FROM AUTHOR]

The article presents a study on the parasites of illegally introduced tench fish or the tinca tinca in the Richelieu River, Quebec. The fish escaped from its habitat in the early 1990s and built a reproducing population. Samples of the species were examined and found to have been infected with parasites than those remained in its native habitat. Researchers believed that V. campylancristrota, a pathogenic metacestode arrived together with the tench in the Richilieu river.