Schindleria parva,a new species of Schindler's fish (Teleostei: Schindleriidae: Schindleria) from Jeddah,Saudi Arabia,Red Sea

Schindleria parva, a new species of the family Schindleriidae, is described from two specimens collected from the central Red Sea of Saudi Arabia. The new species is characterized by lack of pigmentation on the body, possession of an inconspicuous gas bladder and the presence of small teeth on the premaxillae. The holotype is a female of 11 mm standard length (SL) (11.9 mm total length) and the paratype is a male of 9 mm SL. Dorsal fin rays 10 (9) anal fin rays 9 (7). The body depth at pectoral-fin origin 5% (4%) of SL, depth at anal-fin origin 8% (7%) SL, predorsal length 63% (65%) SL, preanal length 72% (72%) SL, the first anal-fin ray situated below the fourth dorsal-fin ray), a total of 23 + 16 myomeres. The female contained a series of 30 rectangular eggs in a single row, whereas the male is characterized by a short rod-like urogenital papilla. Species of the genus Schindleria are likely the smallest marine vertebrates on the planet and S. parva is likely the smallest Schindleria species in the Red Sea. The global diversity of Schindleria is likely underestimated due to the paedomorphic features of this genus. Its fast generation times make it a species-rich genus of high turnover rates, thus potentially highly important for the trophic food webs of coral reefs. Thus, this finding advances knowledge on the biodiversity of the Red Sea, highlights its conservation significance, and contributes towards the understanding of the complexity of the coral-reef fish community.     

Reef fishes community structure of Playa Mero, Parque Nacional Morrocoy, Venezuela

The coral reef fish community was studied in Playa Mero, Morrocoy National Park, after the mass mortality of January, 1996 with a systematic sampling design. Transects and quadrates were used for corals, and a visual census for fishes. The coral community is highly disturbed with extensive areas of dead coral covered by algae, and low coverage and richness of coral species, gorgonians, sponges and briozooans. These factors have generated a relatively homogeneous environment with respect to the fish community, which was dominated by Scaridae and Pomacentridae that represented 75% of fish. Dominant fishes were mainly herbivorous (75.4% of all fish) apparently because of the disturbance that caused the settling of algae.     

The relationship between the position of the retinal area centralis and feeding behaviour in juvenile black bream Acanthopagrus butcheri (Sparidae: Teleostei)

The topography of the neurons in the retinal ganglion cell layer of juvenile black bream Acanthopagrus butcheri changes during development. The region of high cell density the area centralis (AC), relocates from a temporal (central) to a dorsal (peripheral) position within the dorso-temporal retinal quadrant. To ascertain whether the differences in the position of the AC during development are related to feeding behaviour, we monitored fishes that were given a choice of food. A range of feeding behaviour patterns was recorded in individual fishes. The smallest fishes (8-15 mm standard length (SL)) took live food from the water column. Following weaning onto pellets, fishes exhibited a preference for taking food from either the substrate or the surface (but not both). When greater than 20 mm SL, a number of individuals then divided their time between surface and substrate feeding before all fishes became exclusive benthic feeders at a stage between 50 and 80 mm SL. Three individual fishes, for which behaviour patterns were categorized, were killed and the topography of the retinal ganglion cell layer analysed. A range of positions for the AC was found with the smallest fish (12 mm SL) possessing a region of high cell density in the temporal retina. In a larger fish (70 mm SL), feeding from both the substrate and the surface, the AC was found in an intermediate dorso-temporal position. The AC of a fish (51 mm SL) preferentially taking food from the substrate was located in a dorsal position.     

Diet and scavenging habits of the smooth skate Dipturus innominatus

The diet of smooth skate Dipturus innominatus was determined from examination of stomach contents of 321 specimens of 29·3-152·0 cm pelvic length, sampled from research and commercial trawlers at depths of 231-789 m on Chatham Rise, New Zealand. The diet was dominated by the benthic decapods Metanephrops challengeri and Munida gracilis, the natant decapod Campylonotus rathbunae and fishes from 17 families, of which hoki Macruronus novaezelandiae, sea perch Helicolenus barathri, various Macrouridae and a variety of discarded fishes were the most important. Multivariate analyses indicated the best predictors of diet variability were D. innominatus length and a spatial model. The diet of small D. innominatus was predominantly small crustaceans, with larger crustaceans, fishes and then scavenged discarded fishes increasing in importance as D. innominatus got larger. Scavenged discards were obvious as fish heads or tails only, or skeletal remains after filleting, often from pelagic species. Demersal fish prey were most frequent on the south and west Chatham Rise, in areas where commercial fishing was most active. Dipturus innominatus are highly vulnerable to overfishing, but discarding practices by commercial fishing vessels may provide a positive feedback to populations through improved scavenging opportunities.     

贵州荔波发现弱须洞鳅

洞鳅属（Troglonectes Zhang, Zhao & Tang 2016）鱼类为中国特有的小型洞穴淡水鱼类,主要分布在贵州和广西喀斯特地区的地下河流中。2018至2019年在贵州省荔波县境内进行洞穴生物多样性调查时采集到4号洞鳅属标本,经过形态比较,与弱须洞鳅（Troglonectes barbatus）相似;基于线粒体16S rRNA和Cyt b重建的系统发育树及遗传距离分析显示,4号洞鳅属标本与来自模式产地的弱须洞鳅高度支持聚为一支;利用Kimura双参数模型计算基于16S rRNA和Cyt b的遗传距离,这些标本与弱须洞鳅之间的遗传距离分别为0.4%和0.2%,小于洞鳅属物种之间的遗传距离（16S rRNA遗传距离为2.4%,Cyt b遗传距离为6.1%）。本次研究使用16S rRNA和Cyt b分子标记研究洞鳅属部分物种的系统发育关系和遗传距离。综合形态和分子系统发育分析结果,确定采集自贵州省荔波县小七孔景区的4号标本为隶属于鲤形目条鳅科洞鳅属的弱须洞鳅,系贵州省洞穴鱼类新记录种。     

A surgical operating apparatus for fish and its use in the pinealectomy of salmonids

A surgical operating apparatus for fish that is effective for cranial surgery is described. The fishes are secured with clamp-arms which extend against the pectoral and pelvic girdles. The head is held by a plexiglass mouthpiece, designed specifically for the fish species under investigation. The mouthpiece is also responsible for gill irrigation. The use of the apparatus for the surgical pinealectomy of salmonids is described.     

High Endemicity with Clonorchis sinensis Metacercariae in Fish from Yongjeon-cheon (Stream) in Cheongsong-gun,Gyeongsangbuk-do,Korea

The infection status with Clonorchis sinensis metacercariae (CsMc) was examined in freshwater fishes from Yongjeon-cheon (a branch of Nakdong-gang) located in Cheongsong-gun, Gyeongsangbuk-do, the Republic of Korea (Korea). A total of 750 fishes in 19 species were examined by the artificial digestion method for 2 years (2019 and 2020). CsMc were detected in 378 (51.4%) out of 735 fishes in 14 species (73.7%), and the infection intensity was 666 per fish infected. In 2019, CsMc were found in 172 (68.0%) out of 253 fishes in 10 species, and the infection intensity was 565 per fish infected. In 2020, CsMc were detected in 206 (62.2%) out of 331 fishes in 10 species, and the infection intensity was 751 per fish infected. The other zoonotic trematode, ie. Metagonimus spp., Centrocestus armatus, Echinostoma spp. and Clinostomum complanatum, metacercariae were also detected in fishes from the survey streams, but their endemicities were relatively low. Conclusively, it was first confirmed that CsMc are highly endemic in fishes from Yongjeon-cheon in Cheongsong-gun, Gyeongsangbuk-do, Korea.     

Comparative analysis of a 229-kb medaka genomic region, containing the zic1 and zic4 genes, with Fugu, human, and mouse

Medaka is one of the prominent model animals, which also include other fishes such as Fugu and zebrafish. Its genome is relatively compact but has not been well characterized. Here we have sequenced a 229-kb region of medaka, containing the Double anal fin (Da) locus, and compared its structure to those in Fugu, human, and mouse. This region, representing a gene-poor region, contains no major rearrangements and can be readily compared among different species. Comparison of G+C contents and repeats suggested that medaka and Fugu are highly related as expected and that medaka is more similar to mammals than Fugu is. Sequence comparisons of developmental genes zic1 and zic4, identified within this region, revealed that zic1, but not zic4, is highly conserved among vertebrates. The 5' coding region of zic4 is, however, extremely homologous among fishes with little synonymous substitutions, implying its distinct function in fish.     

New genus and species of the family stichaeidae from Hokkaido,Japan

Specimens of a new genus and species of the stichaeid fish,Leptostichaeus pumilus, were collected from the Okhotsk Sea off Hokkaido in Japan. The present new genus and species clearly differs from all the other genera and species of the stichaeid fishes in the following characters: 3 or 4 pectoral fin rays; 10 or fewer caudal principal rays; 79–82 dorsal spines; no pelvic fin; last interneural spine supporting a single dorsal spine; infraorbital, occipital and lateral line canals absent; moderate size of dorsal spine shorter than eye diameter; membranes of dorsal and anal fins widely connected with caudal fin; a large black spot divided by a yellow band present just above gill cover.     

Plagioscion squamosissimus (Sciaenidae) and Parachromis managuensis (Cichlidae): a threat to native fishes of the Doce River in Minas Gerais, Brazil

The middle section of the lake basin of the Doce River in Minas Gerais State, Brazil is plagued by grave environmental problems, including the introduction of non-native fish, which reduces the biodiversity of this region. This study reports the presence of two newly-detected non-native species in the Doce River Basin. Sampling efforts included gill nets with mesh size of 3 to 12 mm (measured diagonally) and trawling nets, both of which were used in independent field campaigns in 2002 and 2011. The two new invasive Perciform fishes, Plagioscion squamosissimus (Heckel 1840) and Parachromis managuensis (Günther 1867) were collected in Caratinga and Rio Doce municipalities. These records and other reports on non-native fishes suggest favorable environmental conditions for the establishment of invasive species in this drainage. These invasive species have behavior and diet observed in other wide distribution exotic fish of Rio Doce Basin representing a threat to the 77 native fishes of this region, 37 of which are endangered.     

Alien Fishes in Natural Streams: Fish Distribution, Assemblage Structure, and Conservation in the Cosumnes River, California, U.S.A.

The Cosumnes River is the largest stream without a major dam on its mainstem in the Sacramento–San Joaquin drainage, central California, U.S.A. We studied its fishes over a 3-year period to answer the following questions: (1) Was the native fish fauna still present? (2) Why were alien fishes so abundant in a river system with a 'natural' flow regime, which elsewhere has been shown to favor native fishes? (3) Were there assemblages of fishes that reflected environmental differences created by the underlying geology? (4) Were there features of the watershed that consistently favored native fishes or that could be managed to favor native fishes? Of the 25 species collected, 17 were alien species; 14 species (five native) were abundant or widely distributed enough to use in detailed analyses. Of the native species, only rainbow trout, Oncorhynchus mykiss, still occupied much of its native range in headwater streams. Other native species have been extirpated or persisted mainly above barriers to alien invasions. The most widely distributed alien species was redeye bass, Micropterus coosae, previously unknown from the river, whose abundance was associated with low-numbers of native species. Other aliens were found primarily in low-land habitats on the valley floor or foothills. Canonical Correspondence Analysis indicated that both native and alien species located on environmental gradients determined largely by elevation, temperature, flow, and emergent vegetation, but the associations with these variables were not strong. While most alien fishes were found in lowland sections of river flowing through agricultural regions, the general relationships between species abundance and landscape-level variables were weak. Assemblages of fishes were poorly defined mixtures of native and alien species. The strikingly distinct geological regions of the basin no longer supported distinct fish assemblages. Species distributions were highly individualistic, reflecting dynamic patterns of introductions, invasions, and local extinctions, as well as physiological tolerances and life history patterns. Most native fishes are likely to persist in the Cosumnes River only if summer flows are increased and if populations above natural barriers are protected from further invasions by alien species, especially redeye bass. General conclusions from this study include: (1) altered habitats can support native species under some circumstances; (2) new fish assemblages with characteristics of 'natural' communities are likely to develop in invaded systems; (3) restoring flow regimes to favor native fishes may require restoring minimum summer flows as well as high channel-forming flows. However, reversing or even reducing, the impact of the predatory redeye bass, pre-adapted for California streams, is probably not possible.     

Ecology of fishes in a high-latitude,turbid river with implications for the impacts of hydrokinetic devices

Hydrokinetic devices generate electricity by capturing kinetic energy from flowing water as it moves across or through a rotor, without impounding or diverting the water source. The Tanana River in Alaska, a turbid glacial system, has been selected as a pilot location to evaluate the effects of such a device on fish communities that are highly valued by subsistence, sport, and commercial users. The basic ecology and habitat use of fishes in turbid glacial systems are poorly understood; therefore it is necessary to study the species composition of the fish community and the spatial and temporal patterns of mainstem river use by these fishes to evaluate impacts of a hydrokinetic device. In this document, we provide an overview of existing knowledge of fish ecology in the Tanana River and impacts of hydrokinetic devices on fishes in other river systems. Seventeen fish species are known to inhabit the Tanana River and several may utilize the deepest and fastest section of the channel, the probable deployment location for the hydrokinetic device, as a seasonal migration corridor. Previous studies in clearwater river systems indicate that mortality and injury rates from turbine passage are low. However, the results from these studies may not apply to the Tanana River because of its distinctive physical properties. To rectify this shortcoming, a conceptual framework for a comprehensive fish ecology study is recommended to determine the impacts of hydrokinetic devices on fishes in turbid, glacial rivers.     

Zooplankton,fish and fisheries in tropical freshwaters

About 40% of all fish species occur in freshwater, although only 1% of the globe is occupied by freshwaters. The tropics harbour a high percentage of these fishes. Freshwater zooplankton on the other hand is far less diverse than its marine counterpart and the tropics do not harbour a markedly high percentage of freshwater species either. The antecedents of freshwater zooplankton appear to have come from riverine and terrestrial habitats via temporary habitats (ponds, floodplains). The present zooplankton composition has also been shaped by, among other factors, the highly efficient zooplanktivorous modern teleosts which have restricted the formerly widespread Branchiopoda mainly to fishless freshwaters. Those Branchiopoda frequently co-existing with fishes (Cladocera) have their size composition strongly influenced by fish predation. Circumstantial evidence indicates that pelagic zooplankton (Cladocera, Copepoda, Rotifera) appear to provide a relatively scarce food supply relative to the littoral region for the early stages of fishes. Also, unpredictability of zooplankton may be involved here. These factors have led to the loss of planktonic eggs and the siting of fish breeding in shallow littoral situations, where other animal foods besides zooplankton are also available, especially for later stages of juvenile fish. The Ostariophysi breed in the shallow expanses of flood waters while the Cichlidae, some of which breed like Ostariophysi, also breed in standing waters in the littoral of lakes or floodplains. In all these locations zooplankton and benthic organisms, especially insects, are available. The cichlids are, in addition, provided with parental care. Predation on young fishes is also reduced by these strategies. Young fishes may also be adapted to feed on patches of zooplankton and other food in their breeding grounds. Tropical pelagic clupeids and cyprinids may breed continuously. Some of these clupeids in rivers breed at low water.Zooplankton, supplemented by other animal food is more critical to achieving the potential fish yields in the tropics than in temperate freshwaters because fish yields in the tropics can be very high indeed. The high metabolic rate of young fishes in the tropics adds to the demand for food. Tropical freshwaters have a relatively high primary production but a low zooplankton/phytoplankton ratio. Zooplankton is kept small in size and biomass by continuous predation. Herbivorous fishes can sustain very high fish yields in the tropics but they must have a high fecundity and high survival of young produced seasonally, mainly in rivers or even continuously as in lakes and reservoirs to weather predation. Rich littoral zooplankton and benthos combined with omnivory and a higher efficiency in the use of the available animal food by newly hatched fishes may be critical factors linking fish yields to zooplankton in tropical freshwaters. The ability of herbivorous tilapias to give very high fish yields in shallow tropical lakes may also be due to their efficient use of animal food, algae and microphagy in young stages besides other favourable adaptations like opportunistic feeding on detrities and the ability to feed on and digest cyanobacteria, abundant in the tropics.     

云南绿汁江鱼类的形态特征及其适应意义

绿汁江的鱼类大致可分为侧扁型,圆筒型和平扁型三种类型。在各种类型中,鱼体上又有不同的形态结构产生。以形态－功能－适应三位一体分析法为指导原则,探讨和阐述了鱼类的形态结构与栖息环境的相互关系。     

Food and feeding ecology of piscivorous fishes at Lake St Lucia, Zululand

The food and feeding ecology of piscivorous fish in Lake St Lucia was monitored for two years. Piscivorous fishes feed predominantly on the planktivorous Gilchristella aestuarius and Thryssa vitrirostris but a wide range of prey species was recorded. Numbers of the predominant piscivores, Argyrosomus hololepidotus and Elops machnata , in an area appear to be related to the densities of their major prey, T. vitrirostris and G. aestuarius . Large piscivorous fishes are restricted to the deeper portions of the lake, whereas small piscivores such as Johnius belengerii and Terapon jarbua feed predominantly on small fishes in the littoral zone. The highly significant correlation between the composition of prey fish species in the lake and prey fish species in the diet of piscivorous fishes, indicates that piscivores are feeding in a density dependent manner. However, factors such as habitat, fish size and swimming speed of prey species are shown to be important in prey selection. Juvenile fish of species such as Sarotherodon mossambicus, Liza macrolepis and Acanthopagrus berda remain in shallow marginal areas, thus avoiding large piscivorous fishes. However by frequenting shallow areas these species become vulnerable to bird predators, especially egrets and herons.     

A new species of Henneguya (Myxozoa) in the big-eyed scad (Selar crumenophthalmus) from Hawaii

We describe a new myxozoan, Henneguya akule n. sp., infecting the carangid fish Selar crumenophthalmus in Hawaii. Spores were found only in the aortic bulb, characterized by elliptical capsule with 2 tails, and pyriform polar capsules that angled toward the anterior end of the spore. Polar filaments had 3-4 coils. Parasites were present in apparently healthy fishes and caused no evident gross pathology. On microscopy, parasites evinced a mild inflammatory response in the host characterized by accumulations of eosinophilic fibrillar material around spores and a mononuclear infiltrate in the adventitia of the bulbus arteriosus. Overall prevalence was 20%, and prevalence between 2001 and 2006 ranged from 12 to 27%, but did not differ significantly between years. In contrast, prevalence of infection was highest in south-central Oahu. There was no relationship between infection status and body condition or gender of fish, and infection was absent in the smallest and largest fishes. Phylogenetically, H. akule n. sp. is most closely related to other Henneguya species infecting the heart of marine fishes based on ribosomal DNA analysis. This is the first documentation of a myxozoan parasite in marine fishes from Hawaii.     

Life history plasticity does not confer resilience to environmental change in the mole salamander (<Emphasis Type="Italic">Ambystoma talpoideum)</Emphasis>

Plasticity in life history strategies can be advantageous for species that occupy spatially or temporally variable environments. We examined how phenotypic plasticity influences responses of the mole salamander, Ambystoma talpoideum, to disturbance events at the St. Marks National Wildlife Refuge (SMNWR), FL, USA from 2009 to 2014. We observed periods of extensive drought early in the study, in contrast to high rainfall and expansive flooding events in later years. Flooding facilitated colonization of predatory fishes to isolated wetlands across the refuge. We employed multistate occupancy models to determine how this natural experiment influenced the occurrence of aquatic larvae and paedomorphic adults and what implications this may have for the population. We found that, in terms of occurrence, responses to environmental variation differed between larvae and paedomorphs, but plasticity (i.e. the ability to metamorphose rather than remain in aquatic environment) was not sufficient to buffer populations from declining as a result of environmental perturbations. Drought and fish presence negatively influenced occurrence dynamics of larval and paedomorphic mole salamanders and, consequently, contributed to observed short-term declines of this species. Overall occurrence of larval salamanders decreased from 0.611 in 2009 to 0.075 in 2014 and paedomorph occurrence decreased from 0.311 in 2009 to 0.121 in 2014. Although variation in selection pressures has likely maintained this polyphenism previously, our results suggest that continued changes in environmental variability and the persistence of fish in isolated wetlands could lead to a loss of paedomorphosis in the SMNWR population and, ultimately, impact regional persistence in the future.     

Heterogeneity and structure of brain tubulins from cold-adapted Antarctic fishes. Comparison to brain tubulins from a temperate fish and a mammal

Tubulins purified from brain tissue of Antarctic fishes assemble in vitro to form microtubules at the low temperatures experienced by these extreme psychrophiles (Williams, R. C., Jr., Correia, J. J., and DeVries, A. L. (1985) Biochemistry 24, 2790-2798). We have initiated studies to determine the structural requirements for assembly of Antarctic fish tubulins at low temperatures. As a first step we have compared the heterogeneity, structures, amino acid compositions, and net charge of brain tubulins purified from three Antarctic fishes (Notothenia gibberifrons, Notothenia coriiceps neglecta, and Chaenocephalus aceratus), from the temperate channel catfish (Ictalurus punctatus), and from a mammal (the cow). Each preparation contained the alpha- and beta-tubulins and was free of microtubule-associated proteins. When examined by isoelectric focusing and by two-dimensional electrophoresis, brain tubulins from the Antarctic fishes were found to be highly heterogeneous; each was resolved into approximately 20 isoelectric variants. The distributions of the isotubulins from the cold-adapted fishes were similar but differed significantly from those of tubulins from catfish and cow. The average isoelectric points of the alpha- and beta-tubulins from the Antarctic fishes were more basic than the isoelectric points of the corresponding tubulins from bovine brain. Peptide mapping confirmed that tubulins from the Antarctic fishes and the mammal differed in structure. The amino acid compositions of fish and mammalian tubulins were similar, but Antarctic fish tubulins apparently contained fewer Glx residues than did catfish or bovine tubulins. Finally, native tubulins from an Antarctic fish and the cow differed slightly in net negative charge. Thus, brain tubulins from the cold-adapted fishes differ structurally from the tubulins of a temperate fish and of a mammal.     

Effects of group size on the responsiveness of zebrafish, Brachydanio rerio (Hamilton Buchanan), to alanine, a chemical attractant

Previous studies have examined the effects of grouping on the locating (search) phase of foraging and feeding behaviour in fishes. Few studies have examined whether schooling in fishes may facilitate individual foraging by enhancing a group's responsiveness to food odours. The purpose of the current study was to assess the effect of increasing group size on the responsiveness of zebrafish, Brachydanio rerio (Hamilton Buchanan), to L-alanine, an amino acid which is an important constituent of prey odours for many fishes. Based on the results of previous studies, either an increasing or decreasing linear relationship or a unimodal (convex or concave) relationship between responsiveness and group size was expected; the results, however, were bimodal. Groups of four fish were most responsive to alanine, as determined by the mean percentage of occurrences of fish in the area of a behavioural arena (an octagonal fluviarium) into which alanine was infused (at 10⁻³, 10⁻⁴, or 10⁻⁵ M). Groups of two, six and eight fish were significantly less responsive ( P < 0.05) than either groups of four fish or individual fish. The responses of groups of two, six and eight fish were not significantly different from each other.     

Intra-buccal feeding of young in an undescribed Tanganyikan cichlid Microdontochromis sp.

Synopsis The zooplanktivorous cichlid Microdontochromis sp. formed large stationary schools in midwater consisting of mouthbrooding and nonbrooding individuals. Early young smaller than 6.0 mm in standard length were mouthbrooded solely by females, but large young, up to 17.4 mm, were mouthbrooded by both females and males. Mouthbrooding fish took food as actively as nonbrooding fish to nourish the young and themselves. Eggs were 1.9 mm in maximum diameter, among the smallest known for mouthbrooding cichlid fishes. Young which ate food within the parent's buccal cavity showed a 10-fold increase in dry weight during the mouthbrooding period. Data suggested that parents finally farmed out their young into broods of other cichlid fishes.