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Research on recruitment variability has gained momentum in the last years, undoubtedly due to the many unknowns related to climate change impacts. Knowledge about recruitment—the process of small, young fish transitioning to an older, larger life stage—timing and success is especially important for commercial fish species, as it allows predicting the availability of fish and adapting fishing practices for its sustainable exploitation. Predicting tools for determining the combined effect of temperature rise and food quality and quantity reduction (two expected outcomes of climate change) on early-life history traits of fish larvae are valuable for anticipating and adjusting fishing pressure and policy. Here we use a previously published and validated dynamic energy budget (DEB) model for the common sole (Solea solea) and adapt and use the same DEB model for the Senegalese sole (S. senegalensis) to predict the effects of temperature and food availability on Solea spp. early life-history traits. We create seven simulation scenarios, recreating RCP 4.5 and 8.5 Intergovernmental Panel on Climate Change (IPCC) scenarios and including a reduction in food availability. Our results show that temperature and food availability both affect the age at metamorphosis, which is advanced in all scenarios that include a temperature rise and delayed when food is limited. Age at puberty was also affected by the temperature increase but portrayed a more complex response that is dependent on the spawning (batch) period. We discuss the implications of our results in a climate change context.

Background Consistent individual differences in behaviour, known as animal personalities, have been demonstrated within and across species. In fish, studies applying an animal personality approach have been used to resolve variation in physiological and molecular data suggesting a linkage, genotype-phenotype, between behaviour and transcriptome regulation. In this study, using three fish species (zebrafish; Danio rerio, Atlantic salmon; Salmo salar and European sea bass; Dicentrarchus labrax), we firstly address whether personality-specific mRNA transcript abundances are transferrable across distantly-related fish species and secondly whether a proactive transcriptome signature is conserved across all three species. Results Previous zebrafish transcriptome data was used as a foundation to produce a curated list of mRNA transcripts related to animal personality across all three species. mRNA transcript copy numbers for selected gene targets show that differential mRNA transcript abundance in the brain appears to be partially conserved across species relative to personality type. Secondly, we performed RNA-Seq using whole brains from S. salar and D. labrax scoring positively for both behavioural and molecular assays for proactive behaviour. We further enriched this dataset by incorporating a zebrafish brain transcriptome dataset specific to the proactive phenotype. Our results indicate that cross-species molecular signatures related to proactive behaviour are functionally conserved where shared functional pathways suggest that evolutionary convergence may be more important than individual mRNAs. Conclusions Our data supports the proposition that highly polygenic clusters of genes, with small additive effects, likely support the underpinning molecular variation related to the animal personalities in the fish used in this study. The polygenic nature of the proactive brain transcriptome across all three species questions the existence of specific molecular signatures for

Polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) are persistent organic pollutants still present in aquatic environments despite their total or partial ban. Previously, we observed that an environmentally realistic mixture of these compounds affects energy balance, growth, and reproduction in exposed zebrafish (F0), and behavior in their unexposed offspring (F1-F4). In the present work, we performed lipidomic and transcriptomic analyses on brains of zebrafish (F0-F2) from exposed and control lineages to identify molecular changes that could explain the observed phenotypes. The use of both technologies highlighted that F0 zebrafish displayed impaired mitochondrial function and lipid metabolism regulation (depletion in triacylglycerols and phospholipids) which can explain disruption of energy homeostasis. A subset of the regulated biological pathways related to energetic metabolism and neurotransmission were inherited in 12. In addition, there were increasing effects on epigenetic pathways from the F0 to the F2 generation. Altogether, we show that the effects of an environmental exposure to PCBs and PBDEs on energetic metabolism as well as neurotransmission extend over 2 generations of zebrafish, possibly due to transgenerational epigenetic inheritance., Funding Agencies:French National Research Agency (ANR)ANR-13-CESA-020 ANR-10-INBS-09

Cephalopods are the first invertebrate class regulated by the European Union (EU) under Directive 2010/63/EU on the protection of animals used for scientific purposes, which requires prospective assessment of severity of procedures. To assist the scientific community in establishing severity classification for cephalopods, we undertook a web-based survey of the EU cephalopod research community as represented by the participants in the European COoperation on Science and Technology (COST) Action FA1301, CephsInAction'. The survey consisted of 50 scenarios covering a range of procedures involving several cephalopod species at different life stages. Respondents (59 people from 15 countries) either allocated a severity classification to each scenario or indicated that they were unable to decide (UTD). Analyses evaluated score distributions and clustering. Overall, the UTD scores were low (7.0 ± 0.6%) and did not affect the severity classification. Procedures involving paralarvae and killing methods (not specified in Annexe IV) had the highest UTD scores. Consensus on non-recovery procedures was reached consistently, although occasionally non-recovery appeared to be confused with killing methods. Scenarios describing procedures above the lower threshold for regulation, including those describing behavioural studies, were also identified and allocated throughout the full range of severity classifications. Severity classification for scenarios based on different species (e.g. cuttlefish vs. octopus) was consistent, comparable and dependent on potentially more harmful interventions. We found no marked or statistically significant differences in the overall scoring of scenarios between the demographic subgroups (age, sex, PhD and cephalopod experience). The COST Action FA1301 survey data provide a basis for a prospective severity classification for cephalopods to serve as guide for researchers, project assessors and regulators., Les céphalopodes sont la première classe d’invertébrés réglementés par l’Union européenne en vertu de la directive 2009/34/UE sur la protection des animaux utilisés à des fins scientifiques, qui exige une évaluation prospective de la gravité des procédures. Afin d’aider la communauté scientifique à établir une classification de la gravité chez les céphalopodes, nous avons entrepris une enquête en ligne au sein de la communauté de recherche sur les céphalopodes, telles que représentée par les représentants du projet COST (European COoperation on Science and Technology) Action FA1301-CephsInAction. L’enquête comportait 50 scénarios couvrant une gamme de procédures impliquant plusieurs espèces de céphalopodes à différents stades de leur vie. Les répondants (59 personnes provenant de 15 pays) ont attribué une classification de la gravité à chaque scénario, ou ont indiqué qu’ils étaient incapables de décider (UTD). Les analyses évaluaient les scores de distributions et les regroupements. Dans l’ensemble, les scores UTD se sont avérés peu élevés (7,0 ± 0,6%) et n’affectaient pas la classification de la gravité. Les procédures faisant appel à des méthodes d’abattage et impliquant des post-larves (non spécifiées à l’Annexe IV) obtenaient les scores UTD les plus élevés. Le consensus était pour ainsi dire unanime quant aux procédures de non-réanimation, bien que la non-réanimation apparaisse parfois confondue avec les méthodes d’abattage. Les scénarios décrivant des procédures supérieures au «seuil inférieur» en matière de réglementation, y compris ceux qui décrivent les études comportementales, ont également été identifiés et répartis dans toute la gamme des classifications de gravité. La classification de la gravité des scénarios basés sur différentes espèces (p. ex., la seiche par rapport au poulpe) était cohérente, comparable et dépendait d’interventions potentiellement plus nocives. Nous n’avons trouvé aucune différence marquée ni statistiquement significative dans les s, Los cefalópodos son la primera clase de invertebrados regulados por la Unión Europea en virtud de la Directiva 2010/63/UE relativa a la protección de los animales utilizados para fines científicos, que exige una evaluación prospectiva de la gravedad de los procedimientos. Para ayudar a la comunidad científica a establecer una clasificación de la gravedad de los cefalópodos, realizamos una encuesta en Internet sobre la comunidad de investigadores de cefalópodos de la UE, representada por los participantes en la Acción COST (Cooperación Europea en Ciencia y Tecnología) FA1301-CephsInAction. El estudio consistió en 50 escenarios que abarcaban una serie de procedimientos en los que intervenían varias especies de cefalópodos en diferentes etapas de su ciclo de vida. Los encuestados (59 personas de 15 países) asignaron una clasificación de la gravedad a cada escenario, o indicaron que no podían decidir (UTD, por sus siglas en inglés). Los análisis evaluaron las distribuciones de puntuaciones y agrupaciones. En general, las puntuaciones de UTD fueron bajas (7,0 ± 0,6 %) y no afectaron a la clasificación de la gravedad. Los procedimientos que implican paralarvas y métodos de matanza (no especificados en el Anexo IV) tuvieron los puntajes más altos de UTD. El consenso sobre los procedimientos de no recuperación se alcanzó de manera consistente, aunque ocasionalmente la no recuperación parecía confundirse con métodos de matanza. También se identificaron y asignaron escenarios que describían procedimientos por encima del «umbral inferior» para la regulación, incluidos los que describían estudios de comportamiento, a lo largo de toda la gama de clasificaciones de la gravedad. La clasificación de la gravedad de los escenarios basados en diferentes especies (por ejemplo, sepia vs. pulpo) fue consistente, comparable y dependiente de intervenciones potencialmente más dañinas. No se encontraron diferencias marcadas o estadísticamente significativas en la puntuación global de los esc

Bisphenol A (BPA) in eggs prior to fertilization was found to induce long-term metabolic disturbances in juvenile rainbow trout (Oncorhynchus mykiss ). Here we describe these imprinting effects in a Dynamic Energy Budget (DEB) framework, which allows interpretation of the data in an energy allocation context. First, DEB parameters for control rainbow trout were optimized using data extracted from 12 studies in the literature. Several modes of action on DEB parameters were then tested in order to correctly predict weight differences observed in rainbow trout in response to 5 different concentrations of BPA in eggs prior to fertilization. Reduced energy conductance v̇ at day 0, followed by an exponential recovery, was found to closely fit the experimental data. Effects on v̇ lasted beyond the disappearance of the chemical from the body, suggesting an imprinting effect of BPA on energy mobilization from the reserve. Our model predicts that early changes in DEB parameters lead to permanent and irreversible impairment of the metabolic growth acceleration in rainbow trout.

The numbers of potential neurotoxicants in the environment are raising and pose a great risk for humans and the environment. Currently neurotoxicity assessment is mostly performed to predict and prevent harm to human populations. Despite all the efforts invested in the last years in developing novel in vitro or in silico test systems, in vivo tests with rodents are still the only accepted test for neurotoxicity risk assessment in Europe. Despite an increasing number of reports of species showing altered behaviour, neurotoxicity assessment for species in the environment is not required and therefore mostly not performed. Considering the increasing numbers of environmental contaminants with potential neurotoxic potential, eco-neurotoxicity should be also considered in risk assessment. In order to do so novel test systems are needed that can cope with species differences within ecosystems. In the field, online-biomonitoring systems using behavioural information could be used to detect neurotoxic effects and effect-directed analyses could be applied to identify the neurotoxicants causing the effect. Additionally, toxic pressure calculations in combination with mixture modelling could use environmental chemical monitoring data to predict adverse effects and prioritize pollutants for laboratory testing. Cheminformatics based on computational toxicological data from in vitro and in vivo studies could help to identify potential neurotoxicants. An array of in vitro assays covering different modes of action could be applied to screen compounds for neurotoxicity. The selection of in vitro assays could be guided by AOPs relevant for eco-neurotoxicity. In order to be able to perform risk assessment for eco-neurotoxicity, methods need to focus on the most sensitive species in an ecosystem. A test battery using species from different trophic levels might be the best approach. To implement eco-neurotoxicity assessment into European risk assessment, cheminformatics and in vitro scre

Stress enhances or inhibits neurogenesis in mammals and some fish species. The link between the two processes is still unclear. Most studies have been performed in very specific stressful or altered environments. Despite the known inter-individual divergence in coping abilities within populations, the relationship between the stress axis and neurogenesis has never been addressed in unstressed individuals. Here we correlate brain expression of the pcna (proliferating cell nuclear antigen) and neurod1 (neurogenic differentiation factor 1) genes, two markers of neurogenesis, with transcripts of cortisol receptors in three fish species living in very distinct environments. Within the three species, individuals with the highest expression of neurogenesis genes were also those that expressed the high levels of cortisol receptors. Based on these correlations and the hypothesis that mRNA levels are proxies of protein levels, we hypothesize that within unstressed animals, individuals sensitive to cortisol perceive a similar environment to be more stimulating, leading to increased neurogenesis. Although it is difficult to determine whether it is sensitivity to cortisol that affects neurogenesis capacities or the opposite, the proposed pathway is a potentially fruitful avenue that warrants further mechanistic experiments.

Polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) are persistent organic pollutants that have been shown to affect fish life-history traits such as reproductive success, growth and survival. At the individual level, their toxicity and underlying mechanisms of action have been studied through experimental exposure. However, the number of experimental studies approaching marine environmental situations is scarce, i.e., in most cases, individuals are exposed to either single congeners, or single types of molecules, or high concentrations, so that results can hardly be transposed to natural populations. In the present study, we evaluated the effect of chronic dietary exposure to an environmentally realistic marine mixture of PCB and PBDE congeners on zebrafish life-history traits from larval to adult stage. Exposure was conducted through diet from the first meal and throughout the life cycle of the fish. The mixture was composed so as to approach environmentally relevant marine conditions in terms of both congener composition and concentrations. Life-history traits of exposed fish were compared to those of control individuals using several replicate populations in each treatment. We found evidence of slower body growth, but to a larger asymptotic length, and delayed spawning probability in exposed fish. In addition, offspring issued from early spawning events of exposed fish exhibited a lower larval survival under starvation condition. Given their strong dependency on life-history traits, marine fish population dynamics and associated fisheries productivity for commercial species could be affected by such individual-level effects of PCBs and PBDEs on somatic growth, spawning probability and larval survival.

In the north-eastern Atlantic, meagre (Argyrosomus regius) is one of the largest fish living on the shelf and this species has important commercial interest. Over the past two decades, large variations in meagre abundance have been observed with pluri-annual cycles but the factors involved in such variations are still unclear. Trophic interactions between meagre and other species (both prey and competitors) might be one explanatory variable of the observed variations in meagre recruitment and abundance. In the present study, we described the diet of commercial-size meagre in the Bay of Biscay from stomach content and stable isotope analyses, and explored its dietary ontogeny. We found that commercial-size meagres were mostly piscivorous with a diet dominated by clupeiform fish (mainly anchovy and sardine) completed by demersal fish (mainly pout and whiting). Cannibalism also accounted for a non-negligible part of the diet. Interestingly, stable isotope and stomach content analyses showed only a very slight increase in prey length and trophic level during the ontogeny of large meagre after 50 cm of total length and despite a 3 fold-change of the individual length in our sampling. Our results suggested that specific trophic interactions (i.e. bottom-up control by clupeiform fish on meagre population, competitive effects on piscivorous populations or top-down control by meagre on clupeiform fish populations) may occur in the Bay of Biscay and can impact meagre abundance dynamics. Our study underlined the interest to enhance ecological knowledge of prey-predator relationships in the development of ecosystem-based approach to understand trophic controls impacting aquatic living resources and fishery economy.

Adaptive phenotypic plasticity is a key component of the ability of organisms to cope with changing environmental conditions. Fish have been shown to exhibit a substantial level of phenotypic plasticity in response to abiotic and biotic factors. In the present study, we investigate the link between environmental sensitivity assessed globally (revealed by phenotypic variation in body weight) and more targeted physiological and behavioral indicators that are generally used to assess the sensitivity of a fish to environmental stressors. We took advantage of original biological material, the rainbow trout isogenic lines, which allowed the disentangling of the genetic and environmental parts of the phenotypic variance. Ten lines were characterized for the changes of body weight variability (weight measurements taken every month during 18 months), the plasma cortisol response to confinement stress (3 challenges) and a set of selected behavioral indicators. This study unambiguously demonstrated the existence of genetic determinism of environmental sensitivity, with some lines being particularly sensitive to environmental fluctuations and others rather insensitive. Correlations between coefficient of variation (CV) for body weight and behavioral and physiological traits were observed. This confirmed that CV for body weight could be used as an indicator of environmental sensitivity. As the relationship between indicators (CV weight, risk-taking, exploration and cortisol) was shown to be likely depending on the nature and intensity of the stressor, the joint use of several indicators should help to investigate the biological complexity of environmental sensitivity.

Zebrafish were exposed through diet to two environmentally relevant polycyclic aromatic hydrocarbons (PAHs) mixtures of contrasted compositions, one of pyrolytic (PY) origin and one from light crude oil (LO). Monoamine concentrations were quantified in the brains of the fish after six month of exposure. A significant decrease in noradrenaline (NA) was observed in fish exposed to both mixtures, while a decrease in serotonin (5HT) and dopamine (DA) was observed only in LO-exposed fish. A decrease in metabolites of 5HT and DA was observed in fish exposed to both mixtures. Several behavioural disruptions were observed that depended on mixtures, and parallels were made with changes in monoamine concentrations. Indeed, we observed an increase in anxiety in fish exposed to both mixtures, which could be related to the decrease in 5HT and/or NA, while disruptions of daily activity rhythms were observed in LO fish, which could be related to the decrease in DA. Taken together, these results showed that (i) chronic exposures to PAHs mixtures disrupted brain monoamine contents, which could underlie behavioural disruptions, and that (ii) the biological responses depended on mixture compositions

Nile tilapia Oreochromis niloticus (NT) and Black-chinned tilapia Sarotherodon melanotheron (BCT) are respectively characterized by fast growth and water salinity tolerance which attract the farmers who could take advantage of both species characteristics by producing hybrids reared in brackish or marine waters. Little information is however available about social interactions between the two species which are distinct by their mode of parental care (oral incubation). The objective of this study was to determine the behaviour of the two species, NT and BCT placed in freshwater intraspecific and interspecific pairing contexts. Females of both species (n = 20 per species) were first isolated for 90 days in a 60 L aquarium to determine the average duration between spawning in the absence of males. With the approach of 4th spawning or after 90 days of isolation, intra and interspecific pairing (fish average weight 200.4 ± 5.1 g) were made 10 times by pairing mode in a 350 L aquarium. The day after fish pairing, 15 min videos were recorded at one hour intervals from 8:00 h to 17:00 h, and courtship and aggressiveness behaviour were quantified. The results showed that isolated NT females had an average duration between two spawning of 15.9 days. No spawning was observed in BCT females. Spawning events were observed in the NT intraspecific pairs, with strictly maternal oral egg incubations. Behavioural differences and some similarities were noted between the two species. NT male was the most dominant in front of females of both species and NT females showed dominance on BCT males. No clear hierarchy was observed in BCT pairs. Courtship behaviours were observed in all pairings with longer durations in NT pairs. Nest building was observed from 8:00 h to 17:00 h in both sexes of BCT and male NT. NT females built nests from 11:00 h with longer durations when paired with males BCT than when paired with their conspecific males. These first results, reflecting behavioural plastic

Fish learning and cognition are usually approached by testing single individuals in various devices such as mazes that have serious drawbacks, especially in gregarious species, including the stress induced by the test procedure. This might impair the results and lead to misinterpretation about the learning abilities of the targeted species. In order to provide an alternative to the individual-based tests, we investigated for the first time the operant conditioning of four similar groups (50 individuals per tank) of sea bass. We used two computerized self-feeder devices per tank, each coupled with individual electronic identification and that were alternately activated during varying positive appetitive reinforcement period of time (7 to 1 day). Learning abilities were examined at both group and individual levels. At the group level, the operant conditioning was demonstrated as the triggering activity significantly decreased when the device was turned off and increased when it was turned on, whatever the reinforcement period duration. The individual level analysis revealed a more complex situation with fish showing different learning performances that can be best explained through the producer-scrounger game theory.

Hybridization aims at combining valuable traits from two species into a single group. Nile tilapia Oreochromis niloticus (NT) and Black-chinned tilapia Sarotherodon melanotheron (BCT) are respectively characterized by fast growth and water salinity tolerance which attract the breeders who could take advantage of both species. The first step is to characterize both species behavior in different contexts. The aim of this study was to compare the self-feeding behaviour between NT and BCT with a design allowing to reveal individual and group feed demand behaviour and then to identify the individual specialization that builds around the device and the food dispenser. The second objective was to estimate the links between the individual specialization and personality traits. To this aim, we recorded feed demand behaviour of both species using a computerized self-feeding device (two tanks for each species containing 20 PIT-tagged individuals with a male-female ratio of about 47%). Personality traits of all individuals were subsequently characterized with an open field test (OFT). The links between feed-demand and personality were then analyzed. Growth performances were not significantly different between NT and BCT but there was a strong tank effect. The individual specialization was similar in NT and BCT and similar to that previously observed in sea bass i.e. 1–3 individuals responsible for most of the feed demand activity in the tanks. Most NT individuals stayed in the shelter during the open field test while most of BCT individuals moved out of it. Overall, NT were shyer than BCT or the OFT was not adapted to NT. Linking the results of the self-feeding experiment and OFT in BCT, we found a strong positive correlation between the triggering activity and females’ shyness. Fish that spent more time inside than outside the shelter and which latency to emerge from shelter was longer, were characterized by a higher triggering activity (high-triggering fish). This study confi

Individual differences in physiological and behavioural responses to stressors are increasingly recognised as adaptive variation and thus raw material for evolution and fish farming improvements including selective breeding. Such individual variation has been evolutionarily conserved and is present in all vertebrate taxa including fish. In farmed animals, the interest in consistent trait associations, that is coping styles, has increased dramatically over the last years because many studies have demonstrated links to performance traits, health and disease susceptibility and welfare. This study will review (i) the main behavioural, neuroendocrine, cognitive and emotional differences between reactive and proactive coping styles in farmed fish; (ii) the methodological approaches used to identify coping styles in farmed fish, including individual (group) mass-screening tests; and (iii) how knowledge on coping styles may contribute to improved sustainability of the aquaculture industry, including welfare and performance of farmed fish. Moreover, we will suggest areas for future research, where genetic basis (heritability/epigenetic) of coping styles, and the neuroendocrine mechanisms behind consistent as well as flexible behavioural patterns are pinpointed as central themes. In addition, the ontogeny of coping styles and the influence of age, social context and environmental change in coping styles will also be discussed.

Polycyclic aromatic hydrocarbons (PAHs) constitute a large family of organic pollutants emitted in the environment as complex mixtures, the compositions of which depend on origin. Among a wide range of physiological defects, PAHs are suspected to be involved in disruption of reproduction. In an aquatic environment, the trophic route is an important source of chronic exposure to PAHs. Here, we performed trophic exposure of zebrafish to three fractions of different origin, one pyrolytic and two petrogenic. Produced diets contained PAHs at environmental concentrations. Reproductive traits were analyzed at individual, tissue and molecular levels. Reproductive success and cumulative eggs number were disrupted after exposure to all three fractions, albeit to various extents depending on the fraction and concentrations. Histological analyses revealed ovary maturation defects after exposure to all three fractions as well as degeneration after exposure to a pyrolytic fraction. In testis, hypoplasia was observed after exposure to petrogenic fractions. Genes expression analysis in gonads has allowed us to establish common pathways such as endocrine disruption or differentiation/maturation defects. Taken altogether, these results indicate that PAHs can indeed disrupt fish reproduction and that different fractions trigger different pathways resulting in different effects.

To understand the genetic basis of coping style in European seabass, fish from a full factorial mating (10 females x 50 males) were reared in common garden and individually tagged. Individuals coping style was characterized through behavior tests at four different ages, categorizing fish into proactive or reactive: a hypoxia avoidance test (at 255 days post hatching, dph) and 3 risk-taking tests (at 276, 286 and 304 dph). We observed significant heritability of the coping style, higher for the average of risk-taking scores (h2 = 0.45 ± 0.14) than for the hypoxia avoidance test (h2 = 0.19 ± 0.10). The genetic correlations between the three risk-taking scores were very high (rA = 0.96–0.99) showing that although their repeatability was moderately high (rP = 0.64–0.72), successive risk-taking tests evaluated the same genetic variation. A mild genetic correlation between the results of the hypoxia avoidance test and the average of risk-taking scores (0.45 ± 0.27) suggested that hypoxia avoidance and risk-taking tests do not address exactly the same behavioral and physiological responses. Genetic correlations between weight and risk taking traits showed negative values whatever the test used in our population i.e. reactive individual weights were larger. The results of this quantitative genetic analysis suggest a potential for the development of selection programs based on coping styles that could increase seabass welfare without altering growth performances. Overall, it also contributes to a better understanding of the origin and the significance of individual behavioral differences.

Biological variability is no longer considered as statistical noise, but rather as an adaptive benefit. This variability comes from consistent differences in behavioral and physiological responses among individuals to a changing/challenging environment, named “coping style”, “temperament” or “personality”. Many studies have described how to characterize personality traits and how to assess their consistency over time and between different contexts; however, little is known about the environmental factors shaping personality development. Because contrasting personalities are maintained with evolution, this lead to the widespread assumption that genes play a predominant role in personality. In many cases, personality traits are however also likely to be determined by individual experience, which is probably at least as important as genetics in shaping personality. The aim of this study was to assess how environmental variability (herein food predictability) impacts behavioral responses, particularly the shyness-boldness axis, one of the most widely shared animal personality trait. Here, we reared juvenile seabass (95 days old) from two divergent strains selected for feed deprivation tolerance under standard conditions for 40 days. Thereafter, we submitted them to two feeding treatments (Predictable vs Unpredictable) starting at 135 dph and lasting 60 days. Seabass reared under a predictable food supply (PFS) grew faster and were shyer than fish reared under an unpredictable food supply (UFS) (i.e. they took more time to exit the refuge zone of a Z-maze; UFS: 132.47 ± 34.63 s; PFS: 336.79 ± 56.97 s) but their exploration tendency was similar. We also examined the behavioral responses of these fish facing a hypoxic challenge. Hypoxia tolerance results were consistent before and after the two feeding treatments. Our findings show the importance of early environmental experience as a driving force shaping boldness. In addition, we provide further evidence that predictable