Le gobie Discordipinna filamentosa, pr & eacute;c & eacute;demment connu uniquement du Pacifique nord-ouest (Japon et Malaisie), est signal & eacute; pour la premi & egrave;re fois & agrave; l'ile de Mayotte, sud-ouest de l'oc & eacute;an Indien. Ce nouveau signalement correspond & agrave; une extension de l'aire de r & eacute;partition de l'esp & egrave;ce d'environ 7000 km au sud-ouest de la Malaisie et confirme la pr & eacute;dilection de l'esp & egrave;ce pour la zone m & eacute;sophotique. Cette observation souligne l'importance d'augmenter l'effort de prospection sur les zones peu & eacute;tudi & eacute;es et les habitats r & eacute;cifaux de la zone cr & eacute;pusculaire afin de mieux appr & eacute;hender leur biodiversit & eacute; et leurs fonctionnalit & eacute;s & eacute;cologiques.
The Chiapas killifish (Tlaloc hildebrandi) is an endangered freshwater fish endemic to the highlands of Chiapas, Mexico. This highly restricted species faces ongoing habitat decline and degradation, principally caused by urbanization and pollution, as well as the threat posed by invasive species. The otolith has long been recognized as one of the structures in fish anatomy most useful as a powerful tool for use in fish aging because of its accretionary growth and species-specific shape. The present study analysed annual T. hildebrandi otolith rings, documenting the growth pattern to describe the age and population structure of the species of interest. Otolith analysis revealed that T. hildebrandi range from 0 to 7 years in age, while the frequency distribution of T. hildebrandi length presented seven modes corresponding to seven age classes or cohorts. The length-weight relationship (LWR) equation showed positive-allometric growth (b > 3), with no differences between sexes observed. Additionally, the von Bertalanffy growth equation was expressed as SL: Lt = 142.5(1-e(-0.161(t - 0.264))) and TL: Lt = 169.4 (1-e(-0.155(t - 0.199))). These findings contribute to the understanding of Chiapas killifish age and growth patterns, thus emphasizing the continuous need for research and monitoring to support the management and conservation efforts for this species.
- We describe here for the first time the full mitochondrial genome of two specimens of Pycnochromis nigrurus (Smith, 1960), until recently (Tang et al., 2021) placed in the genus Chromis, a planktivorous fish abundant on coral reef outer slopes in the Indian Ocean, including Reunion Island. The mitochondrial genome is 17,164 bp long and contains 13 protein-coding genes along with 22 tRNA and two rRNA genes and a D-loop region, arranged similarly to other Chrominae species. Distance analyses of complete mitogenomes of representatives of four Pomacentridae genera indicated a closer proximity to the genus Dascyllus, consistent with the last revision of the Pomacentridae by Tang et al. (2021). These mitogenomes are available through GenBank (Accession: OR616239-40).
An annotated and illustrated account of the species of the family Soleidae from the Canary Islands is presented. Solea senegalensis Kaup, 1858 is observed for the first time from this archipelago, bringing the total number of soleid species in the region to five. Erroneous or insufficiently documented records of Soleidae in the Canary Islands are also discussed. The absence of Microchirus hexophthalmus (Bennett, 1831), Solea solea (Linnaeus, 1758), Bathysolea profundicola (Vaillant, 1888), and Dicologlossa cuneata (Moreau, 1881) from the Canaries is confirmed. Additional information on the ecology, biology, and bathymetric distribution of the Canarian species is provided and updated. The study also provides English and Canarian Spanish common names to enhance public awareness and support recognition and conservation of these species.
- Hatching is the process by which an individual fish leaves its egg's envelope. According to Cowan et al. (2024), this typically occurs when embryo have reached "certain developmental milestones" or "full embryonic development". Even though we partly agree that hatching occurs when embryo has reached a "normal, species-specific stage of development", this does not imply that it has "undergone the complete developmental process". Therefore, "mature larvae" do not exist, and hence "premature" larvae has logically no biological sense, and more generally "preor pro-something" must be avoided. There is another reason to abandon the concept of "premature larva", which designates a fate. There is no fate in biological development. Development is not the deployment of a program, but a journey where you can find accidents.
Actinopterygii fishes exhibit remarkable reproductive diversity, encompassing a wide array of sex determination mechanisms, mating systems, and parental care behaviours. While external fertilization and high fecundity are predominant characteristics, numerous exceptions reveal intricate evolutionary adaptations across families. This literature review analyzes the reproductive traits of 23 species-rich fish families, covering approximately 37% of fish biodiversity with a vast literature. It presents aspects of sex determination, hermaphroditism and sex-change, spawning sites and nesting, courtship behaviour and sensory modalities, intra-and intersexual selection, sex dimorphism, mating system and parental care. Interesting patterns emerged and knowledge gaps are presented and discussed. Understanding fish reproductive behaviour is essential for ecological and conservation purposes. By synthesizing available data across taxonomic groups, this review provides a framework for future studies, presenting the complexity of reproductive adaptations and their roles in population dynamics and fish evolution.
- The effectiveness of Marine Protected Areas (MPAs) relies on their spatial configuration and their ability to cover the range of movements and habitats of target species. Understanding the movement behaviour of fish is hence critical for the effective management of MPAs. This pilot study aimed to provide some insights on the movement patterns of white sea bream (Diplodus sargus), a key ecological and commercial species, in the Torre Guaceto MPA (Italy), particularly the potential use of the highest protection levels (zones A and B) of the MPA by individuals from the largest zone of the MPA (zone C). We used an array of ten acoustic receivers deployed across the restricted zones A and B of the MPA and employed acoustic telemetry to monitor twelve tagged individuals originating from the zone C from May 2022 to February 2023 (33 weeks in total). Data analysis revealed that most tagged fish were detected shortly after release near the MPA borders, particularly in zone A (i.e., higher presence index), which is characterized by Posidonia oceanica beds, indicating a potential habitat preference. However, most individuals exhibited low residency indices in zones A and B, suggesting they went back to zone C. One fish exhibited potential commuter behaviour, while another displayed potential seasonal movement, being detected again during winter months, possibly related to spawning behaviour triggered by suitable seawater temperatures or feeding behaviour. Depth data indicated a diel pattern, with fish moving to deeper waters at night and shallower areas during the day, although there was an inter-individual variability. Notwithstanding the limitations of the present study, the findings emphasise the need to further study intraspecific variation in movement behaviour and provide a foundation for future research in this area. Future research should focus on extended temporal monitoring and comprehensive habitat coverage to optimise Torre Guaceto MPA management strategies for white sea bream.
Cannibalism is a major source of mortality in the early rearing phases of many fish species, among which Eurasian perch (Perca fluviatilis). Even though several studies highlighted the importance of both morphological traits and environmental conditions in shaping cannibalistic behaviour, the role of individual behavioural variation-particularly consistent traits associated with animal personality-remains largely unexplored. In this study, we assessed whether perch larvae identified as cannibals differed from their non-cannibal congeners for behavioural traits such as exploration, activity, boldness (latency to emerge), and shoaling tendency. Behavioural assays were conducted twice for each individual, allowing assessing trait repeatability. Morphological measurements (total length, mass, head size, and mouth dimensions) were also recorded. Principal component analysis revealed that exploration, activity, shoaling tendency, and age were positively correlated and opposed to shyness. Behavioural traits showed moderate repeatability after controlling for age, particularly for exploration, boldness, and shoaling; activity was highly influenced by age, but it was not repeatable. Comparison between cannibals and non-cannibals revealed no consistent differences in behavioural traits, except for lower exploration in cannibals during the first session test. This difference did not persist in the second session, suggesting context-dependent variation rather than fixed personality differences. Morphologically, no significant differences in body size or head/mouth dimensions were found between groups, although trends suggested slightly larger mouth dimensions in cannibals. Our findings suggest that larval cannibalism in Eurasian perch is not strongly associated with neither consistent behavioural nor morphological traits. Rather, it may reflect a plastic, opportunistic strategy influenced by transient internal states (e.g., hunger), environmental conditions such as density, or developmental transitions toward piscivory. This challenges the assumption that personality traits can reliably predict behaviours such as cannibalism in early life stages. Our findings are crucial for optimising larval rearing protocols and improving survival rates in aquaculture.
- Social behaviour involves constant interactions that can modulate emotional states. In fish, emotional contagion-encompassing the spread of both negative and positive affective conditions-has been documented but remains underexplored in group contexts. Here, we investigated how the proportion of stressed individuals within a zebrafish (Danio rerio) group affects collective behaviour in response to a threat. We induced stress in subsets of fish and formed groups of eight with varying ratios of stressed (S) to non-stressed (NS) individuals (0S8NS to 7S1NS; n = 8). Group behaviour was assessed immediately after group formation and again 24 h later following exposure to alarm substance (AS). Our results showed that group cohesion is higher when more non-stressed animals compose it, although locomotor parameters were not changed. After AS exposure, groups with more than 25% of stressed individuals exhibited significant behavioural alterations compared to controls, with increased immobility and altered shoal cohesion under AS. These changes suggest a threshold for stress contagion within the group, where a critical proportion of stressed members amplifies group-level stress responses. Interestingly, groups with similar internal states-whether predominantly stressed or not-were more cohesive during AS exposure, highlighting the importance of social synchrony in stress modulation. This work underscores that stress contagion in zebrafish depends on both the number of stressed individuals and the perceived threat, the idea that social and emotional cues influence collective behaviour in fish.
- Coral reefs are among the most diverse and complex ecosystems. However, these habitats are currently facing severe pressures due to climate change, costal development and coral disease, influencing life on coral reefs. Considering that the degradation of the coral reefs can asymmetrically impact all organisms, we here asked if coral reef condition variability would be associated with change in stress and cleaning behaviour in Caribbean sharknose cleaning gobies Elacatinus evelynae. This study was conducted across five different reefs of the Island of Cura & ccedil;ao. We found significant differences in reef condition, in fish communities, in numbers of cleaning gobies and cleaning stations (i.e., goby territories) across all our sampled reefs. Specifically, the gobies from Carmabi (the most degraded reef) showed simultaneously lower cleaning activity and higher whole-body cortisol levels compared to gobies from other reefs. Collectively, our findings suggest that reef condition status may be implicated to stress and behavioural output variation of cleaning gobies.
Multimodal communication is a widely studied phenomenon across the animal kingdom, generally involving the visual, chemical and acoustic channels. However, most studies do not consider the impact of the daily light intensity variations: for a multitude of species that are dependent on visual cues, the light changes constitute a challenge, which may be solved by a shift from visual to non-visual signalling. In this paper, we examine the impact of light intensity on the visual and acoustic communication of fish during aggressive interactions. First, we describe the aggressive interactions within a stable group of males of the cichlid Maylandia zebra submitted to a light-dark (LD) cycle including 3 phases: low-light (mimicking dusk), daylight, and darkness (night). Under low-light and darkness, the number of aggressions is lower compared to daylight. The presence of aggressive acts in darkness suggests that the triggering of aggression relies on chemical and/or mechanical channels, taking the place of the visual channel under daylight and low-light conditions. Aggressive acts are more frequently accompanied by sounds in darkness (19.5%) than in daylight (8.5%) or low-light (8.5%), suggesting that the relative importance of visual and auditory cues in social interactions depends on environmental constraints affecting each sensory modality. The number of pulses per sound is significantly lower in sounds that accompany nocturnal aggressive acts. We then studied the impact of visual and visual + acoustic stimuli on aggressive interactions occurring under daylight, low-light and darkness conditions, using a fish (opponent) as visual stimulus and sounds from conspecifics as acoustic stimulus. Under the darkness conditions, stimuli have no effect, as the triggering effect of light is absent, and as mechanical and chemical channels cannot play a role due to glass separation between the opponent fish and the test fish. Under low-light conditions, visual + acoustic stimulus has a greater lowering impact on the aggressiveness of the tested males than under daylight conditions. Together, these results demonstrate that senders and receivers optimise their communication during aggressive interactions by adjusting the relative importance of auditory and visual channels according to ambient light conditions. This phenomenon is likely to be widespread in fish and other animals as many species experience a daily light cycle in their natural environment. Furthermore, in the context of increased anthropogenic change, phenotypic plasticity could provide a short-term mean of compensating for disturbances such as increased turbidity that disturbs visual communication.
- Allometric relationships were estimated for nine species of rays from the Atlantic coast of C & ocirc;te d'Ivoire using length-weight and length-length regression analyses. All specimens were collected between February 2022 and May 2023 at the San-Pedro fishing port and the landing sites of Tabou, Grand-B & eacute;r & eacute;by, Monogaga, Jacqueville, Abidjan, and Assinie. A total of 844 specimens were sampled (515 Raja cf. miraletus, 43 Raja parva, 82 Rhinobatos rhinobatos, 30 Rhinobatos albomaculatus, 13 Rhinobatos irvinei, 62 Fontitrygon margaritella, 51 Torpedo torpedo, 27 Dasyatis marmorata, and 21 Zanobatus maculatus). The results showed that most species exhibited negative allometric growth, with b values ranging from 2.376 to 3.378 for length-weight relationships and from 0.615 to 1.065 for length-length relationships. These analyses revealed significant variations in allometric coefficients among species, which may be attributed to ecological and anthropogenic factors specific to C & ocirc;te d'Ivoire. Such differences highlight the need to better understand the growth dynamics of local ray populations for sustainable stock management. This study thus provides essential baseline data for the conservation of elasmobranchs in West Africa and emphasizes the importance of further research in this region.
Le Chirurgien noir, Acanthurus tractus (Poey, 1860), est un poisson originaire de l'Atlantique occidental, principalement des Cara & iuml;bes. Un sp & eacute;cimen de cette esp & egrave;ce a & eacute;t & eacute; observ & eacute; sur l'ile de Corvo, aux A & ccedil;ores, en octobre 2024. Une photographie sous-marine a permis son identification formelle. Le contexte g & eacute;ographique de l'ile et son activit & eacute; commerciale limit & eacute;e avec l'ext & eacute;rieur privil & eacute;gient l'hypoth & egrave;se d'une arriv & eacute;e naturelle. Celle-ci pourrait s'& ecirc;tre produite soit par dispersion durant le stade larvaire p & eacute;lagique, soit par d & eacute;rive & agrave; un stade de d & eacute;veloppement plus avanc & eacute;, dans un radeau d'objets flottants. Cette observation repr & eacute;sente le premier signalement de l'esp & egrave;ce pour les A & ccedil;ores, et possiblement la premi & egrave;re arriv & eacute;e naturelle en Macaron & eacute;sie.
- Sculpins (Psychrolutidae) are valuable biological models for research on coastal fish species due to their robustness, which allows them to be easily maintained in captivity. Additionally, their reproductive strategy-where eggs are deposited in a clutch rather than being released as pelagic eggs-as well as their relatively short generation time offers significant advantages for developmental studies. A literature review of the early life history of Taurulus bubalis is presented and complemented by our own observations and documentation of all developmental stages (from eggs to juveniles). Our description is based on both materials collected in the Northeast Atlantic, the northern Bay of Biscay (Baie de la For & ecirc;t) in north-western France and on aquarium reared specimens. We provide detailed images and measurements with an update on spawning season and new insights on when maturity is reached. Differences between larvae of T. bubalis and larvae of the similar Micrenophrys lilljeborgii, and Myoxocephalus scorpius, are discussed together with a review of their historical and current distributions in the Northeast Atlantic.
In the course of the history of comparative anlatomy, four main types of meaning have been given to the comparison of living beings. Among these, the identification of connections between parts of organisms gained momentum from Etienne Geoffroy Saint-Hilaire onwards, and continues today through phylogenetic purposes. However, anatomists divided themselves into tazonomic sectors between which exchanges remained tenuous, if not non-existent. As a result, we have yet to discover osteological homologies between tetrapods and teleosts, even though these groups have been extensively studied. As an example, we would like to present here the integration of a fully digitized teleost fish skeleton into the Vertebrates application, a digital osteological atlas enabling homologies between different skeletons to be illuminated. This example highlights homologies that are generally not provided in most comparative anatomy treatises, and illustrates the link between the pedagogi-cal dissemination of knowledge and research questions. From a pedagogical and practical point of view, digital exploration of a teleost skeleton is a useful complement to dissection, especially of the smallest bones, and is particularly useful for any student learning comparative anatomy.
- A single specimen of the poorly known anthiadine fish Plectranthias elongatus Wu, Randall & Chen, 2011 from Vanuatu represents the first record of the species from the Southern Hemisphere. The species was previously known from only two specimens, one from Taiwan (type locality) and one from the East China Sea (off the west coast of Kyushu in Japan), in the northwestern Pacific Ocean. The Vanuatu specimen is described in detail and compared with related congeners, including Plectranthias xanthomaculatus Wu, Randall & Chen, 2011, currently also known only from Taiwan and Japan. In addition, several morphometric differences were noted between P. xanthomaculatus and a closely related congener, Plectranthias lasti Randall & Hoese, 1995 (restricted to northwestern Australia), the latter having been treated as a possible senior synonym of the former in recent publications.
The black scorpionfish Scorpaena porcus (Linnaeus, 1758) is one of the main target species in the coastal fisheries of the south-eastern coast of France during the summer season. It lives on rocky bottoms and Posidonia seagrass meadows, contributing significantly to the total fish biomass in these habitats. Biological data (morphometry, diet and reproduction) of S. porcus were recorded on specimens obtained from professional fishermen in the Port-Cros National Park in two areas, which differed of management and fishing regulations: the core area of the Park (CORE) and the adjacent marine area (AMA). The enhanced protection in the CORE contributed to improve the reproductive potential of S. porcus, with bigger oocytes (more reserves), and thus better chances of survival for larvae. In the CORE area, the individuals collected in Porquerolles were more advanced in their reproductive cycle than those from Port-Cros, possibly due to their better body condition. The other biological parameters studied did not show any significant difference between CORE and AMA.
Nine-spined sticklebacks Pungitius spp., like other gasterosteids, display a sexual dimorphism, which is characterised by a colouration change for males during the breeding season. The aim of this study was to describe the male nuptial colouration pattern of two nine-spined stickleback species occurring in France: Pungitius vulgaris and Pungitius laevis, using public aquarium facilities. Our results revealed that male nuptial colouration patterns are distinctive and valuable for taxonomic studies of this genus. In comparison to all male nuptial colouration patterns of the other Pungitius, P. vulgaris is characterised by a body with greenish vermiculations on the back, yellow-greenish flanks, a black belly from the chin to the caudal peduncle (vs. brown-greenish or black vermiculations on the back and a black belly from the chin to the anal spine, or body totally black). In contrast P. laevis displays a body with brown-greenish vermiculations on the back, black belly from the chin to the anal spine (vs. greenish or black vermiculations on the back, yellow-greenish flanks, a black belly from the chin to the caudal peduncle, or body totally black), brown-greenish dorsal spines (vs. greenish, black or blue), its black pelvic spines with white tips (vs. totally black or white), yellow hyaline fins (vs. hyalines, dark or black) and yellow eyes (vs. orange). This study provided the first live traits data for the endemic species P. vulgaris. At last, we also discussed the key role of public aquariums for taxonomic studies.
