Explore the vast range of titles available.

The tiger puffer Takifugu rubripes is one of the most popular aquacultural fish; however, there are two major obstacles to selective breeding. First, they have a long generation time of 2 or 3 years until maturation. Second, the parental tiger puffer has a body size (2–5 kg) much larger than average market size (0.6–1.0 kg). The grass puffer Takifugu niphobles is closely related to the tiger puffer and matures in half the time. Furthermore, grass puffer can be reared in small areas since their maturation weight is about 1/150 that of mature tiger puffer. Therefore, to overcome the obstacles of maturation size and generation time of tiger puffer, we generated surrogate grass puffer that can produce tiger puffer gametes through germ cell transplantation. Approximately 5000 tiger puffer testicular cells were transplanted into the peritoneal cavity of triploid grass puffer larvae at 1 day post hatching. When the recipient fish matured, both males and females produced donor-derived gametes. Through their insemination, we successfully produced donor-derived tiger puffer offspring presenting the same body surface dot pattern, number of dorsal fin rays, and DNA fingerprint as those of the donor tiger puffer, suggesting that the recipient grass puffer produced functional eggs and sperm derived from the donor tiger puffer. Although fine tunings are still needed to improve efficiencies, surrogate grass puffer are expected to accelerate the breeding process of tiger puffer because of their short generation time and small body size.

The common carp Cyprinus carpio is one of the most widely-distributed freshwater fishes in the world. Due to its value for conservation and fisheries in several native/translocated areas of distribution and its detrimental effects on the aquatic ecosystem in most invasive areas, robust age-based population dynamics models are required for successful management of this species. The present study provides a global review of age determination in carp, including a historical account of ageing methods, an assessment of the relative utility of ageing structures, and an evaluation of precision and accuracy (i.e. validation) of age estimates. Historically, scales were by far the most widely-employed structure, followed by the operculum, otolith, dorsal spine, vertebra and fin ray. However, in countries where carp is categorised as ‘high risk’ of impact, use of alternative structures to the scale was predominant. Causal criteria analysis showed scales and opercula to provide inconsistent evidence for successful annulus identification/counting, whereas consistent evidence was found for otoliths, dorsal spines, vertebrae and (pectoral) fin rays. Precision was always above reference thresholds for scales, whereas for otoliths, dorsal spines and fin rays was in several cases below. Accuracy was addressed sporadically and mostly in high-risk countries. It is suggested that dorsal spines or pectoral fin rays should be used in lieu of scales as non-lethal ageing structures, and otoliths (or vertebrae, pending more research) otherwise, and that validation should always be attempted as part of the set-up of more appropriate ageing protocols and use of correct terminology.

The family †Peipiaosteidae contains the genera †Peipiaosteus, †Stichopterus, †Spherosteus, †Yanosteus, and †Liaosteus, all from Late Jurassic to Early Cretaceous deposits of China, Russia, Kazakhstan, and Mongolia. Although the family has taxonomically expanded since it was first established for †P. paniLiu and Zhou, 1965, the amount of detailed comparative data for many of the taxa involved is lacking. In this paper, we describe the osteology of the monotypic genus †Yanosteus from the Yixian Formation (Early Cretaceous) of China largely on the basis of a newly prepared, well-preserved specimen. †Yanosteus is characterized by a series of infraorbital ossicles (a characteristic of the family), a broad, rounded palatopterygoid, a robust dentary, an extremely small opercle and a subopercle with distinctly long and rounded anterior process and a posteriorly scalloped margin, a broad and weakly forked caudal fin, an elongate dorsal fin with more than 160–178 fin rays (diagnostic for the genus), and a short but well-formed pectoral fin spine. We use the results of this study to discuss the characters of the †Peipiaosteioidei and the diversity of †peipiaosteioids.

The genus Mola of ocean sunfishes (family Molidae) is currently composed of three species: Mola mola (Linnaeus 1758), Mola ramsayi (Giglioli 1883), and Mola tecta Nyegaard et al. 2017. For a comprehensive revision of the genus, both literature survey and morphological investigations of Molidae were conducted. We found Mola alexandrini (Ranzani 1839) to be synonymous with M. ramsayi and we herein redescribe M. alexandrini based on the rediscovered dried holotype and 21 other fresh and preserved specimens. Mola alexandrini can be distinguished from other species of Mola by the following combination of characters in adults: head profile with bump; chin with bump; body scales rectangular; clavus rounded, supported by 14–24 (mode 17) clavus fin rays and 8–15 (12) ossicles on the rear margin. A neotype of M. mola is designated for comparison with M. alexandrini, as these two species have long been confused.

The filamentous flounder Arnoglossus nigrofilamentosus n. sp. is described from four specimens collected in the southeastern Mediterranean near Tel-Aviv, Israel on 5 May 2017. The new species is characterized as follows: second to sixth dorsal-fin rays elongate and filamentous, dorsal-fin rays 78-84, anal-fin rays 61-66, pectoral-fin rays on ocular side 12-13, on blind side 7-9, caudal-fin rays iii,11,iii , lateral-line scales 52-54, gill rakers 0 + 4-5, not serrated, interorbital a narrow bony ridge without scales in the middle, interorbital width 11% to 16% of upper orbit diameter, no enlarged teeth anteriorly in upper jaw, and prevomer small, not enlarged, weakly projecting into mouth cavity; body in fresh specimens pale (may have been dark before the epidermis was abrased), head, peritoneum and vertical fins black. The new species is described and compared with similar species. Though the species has not yet been observed in the northern Red Sea, it probably originates from the Gulf of Suez, so this finding represents a probable new case of Lessepsian migration.

Two new species of snailfishes are described from the Aleutian Islands. Both are similar to Careproctus candidus, described originally from four specimens, here redescribed on the basis of 67 specimens in addition to the types. All three species are allocated to the Careproctus subgenus Temnocora. Careproctus candidus is distinguished from all other species of Careproctus by the combination of an anterior dorsal-fin lobe formed by a distinct notch, pupil a horizontal slit, and variegated reddish coloration. It is redescribed to note the presence of prickles, a variable pectoral-girdle morphology, and variable exsertions of the fin rays of the dorsal-fin lobe. Careproctus klisi, new species, is distinguished by having an anterior dorsal fin uniquely of five to seven short anterior dorsal-fin rays nearly equal in length preceding distinctly longer succeeding rays, pupil a horizontal slit, a variegated reddish coloration, and a relatively deep body. Careproctus bromius, new species, is distinguished by having low vertebral and median-fin ray counts, pupil a horizontal slit, a variegated light brown and pale coloration, and in lacking an anterior dorsal-fin lobe. Careproctus candidus ranges across the Aleutian Islands from Attu Island to the northern Gulf of Alaska at depths from 88 to 432 m. Careproctus klisi, new species, is found in the central and western Aleutian Islands from off Buldir Island in the west to Amlia Island in the east at depths from 134 to 180 m. Careproctus bromius, new species, is found in the central and eastern Aleutian Islands from Amchitka Pass to off Akutan Island at depths from 80 to 232 m.

In this paper, we use molecular phylogenetics, micro-CT scanning, and morphological analyses to describe a new species of goby, Pascua marecoralliensis, and demonstrate that the genus Pascua is distinct from Hetereleotris, as supported by five diagnostic characters, including modified basicaudal scales and reduced sensory papillae patterns. Phylogenetic analysis places Pascua as sister to the Gobiodon group, while Hetereleotris forms a separate clade. The new species, P. marecoralliensis, differs from congeners in fin ray counts, cephalic pore patterns, and head morphology and exhibits unique live colouration. Additionally, we reclassify Hetereleotris readerae and H. sticta as Pascua readerae and P. sticta based on shared genus-specific traits. The distribution of Pascua spans the southern Pacific, suggesting a relict lineage or undiscovered diversity in the genus. This work underscores the importance of integrative taxonomic approaches for resolving cryptic diversity in gobioid fishes and highlights the need for further sampling in understudied regions.

The overlapping morphological features, vertebral count, and molecular analysis of the cytochrome C oxidase subunit I mitochondrial gene sequences of the related congener species of the genus Pisodonophis retrieved from the available database clearly show the involvement of multiple species in Pisodonophis boro (Hamilton) complex. The original description of P. boro contains only dorsal and anal fin counts. The vertebral count given by authors never included specimens from the type locality. In order to resolve the confusion in the species complex, a neotype for P. boro has been designated from old collections of Sir Francis Day. Pisodonophis boro is now re-described as having a lower range of vertebrae and fin ray count: 149–156 vertebrae, 334–346 dorsal fin rays, and 232–249 anal fin rays. At the same time, a species having a higher range of vertebrae and fin ray count: 170–173 vertebrae, 374–400 dorsal fin rays, and 248–269 anal fin rays, has been described here as Pisodonophis kalinga sp. nov. The obtained gene sequences of currently identified P . boro form a distinct cluster with a strong bootstrap support of 100%. The gene sequences of Pisodonophis kalinga sp. nov. form a distinct cluster in the maximum likelihood tree analysis with a strong bootstrap support of 99%. The above mentioned molecular analysis is further supported by species delimitation analysis which indicates that at least five species are involved in the reported sequence tagged as P. boro.

The European flounders Platichthys flesus (Linnaeus, 1758) displays two contrasting reproductive behaviors in the Baltic Sea: offshore spawning of pelagic eggs and coastal spawning of demersal eggs, a behavior observed exclusively in the Baltic Sea. Previous studies showed marked differences in behavioral, physiological and life-history traits of flounders with pelagic and demersal eggs. Furthermore, a recent study demonstrated that flounders with pelagic and demersal eggs represent two reproductively isolated, parapatric species arising from two distinct colonization events from the same ancestral population. Using morphological data we first established that the syntypes on which the original description of P. flesus was based belong the pelagic-spawning lineage. We then used a combination of morphological and physiological characters as well as genome-wide genetic data to describe flounders with demersal eggs as a new species: Platichthys solemdali sp. nov. The new species can be clearly distinguished from P. flesus based on egg morphology, egg and sperm physiology as well as via population genetic and phylogenetic analyses. While the two species do show some minor morphological differences in the number of anal and dorsal fin rays, no external morphological feature can be used to unambiguously identify individuals to species. Therefore we developed a simple molecular diagnostic test able to unambiguously distinguish P. solemdali from P. flesus with a single PCR reaction, a tool that should be useful to fishery scientists and managers, as well as to ecologist studying these species.

Aquatic organisms are exposed to a myriad of chemical compounds, with particular concerns focused on endocrine disruptors. Growing scientific evidence indicates that these compounds interfere with normal endocrine function and could affect the reproductive system of humans and wildlife. We analyzed the proportion of masculinized females, defined by elongation and fusion of the anal fin rays, and the extent of masculinization, masculinization index, defined by anal fin length divided by the standard length, of Cnesterodon decemmaculatus resident to areas of agricultural and urban-industrial activities in the Arroyo Colorado basin. Additionally, a bioassay was carried out to assess the potential effects of masculinization on reproductive success, measured as the number of viable progenies, using pregnant females from the site downstream of the urban–industrial zone. Masculinized females were observed in all sampling sites, particularly downstream of the urban–industrial area, where over 80% of females presented abnormal sexual characteristics and the highest masculinization index was registered. In the laboratory, masculinized adult females showed male mating behavior, and survival of their progeny was lower than those of normal females. To our knowledge, this is the first report of endocrine disruption in field-collected C. decemmaculatus, and the first evaluation of the reproductive success of masculinized females. Finally, our results support C. decemmaculatus as an excellent sentinel species due to its wide distribution, easy culture in laboratory conditions, and its potential capability to respond to sources of pollution, particularly endocrine disruptors.