Some observations on the effect of feeding Cirrhina mrigala (Ham.) with Microcystis aeruginosa Kütz.

Summary and Conclusions Feeding experiments were carried out on the fingerlings of C. mrigala to study the effect of Microcystis aeruginosa. It was observed that the alga has no adverse effect on the fish and there is significant increase in weight, volume, length and breadth of the fishes as compared to the two controls (jars no. 2, 3) indicating that the alga is utilized as food and has a beneficial effect on the growth and development of these fishes.     

Nontroglobitic Fishes in Bruffey-Hills Creek Cave, West Virginia, and other Caves Worldwide

Six species of fishes were tagged and released in September and November 1995 and on five dates between November 1998 and October 1999 inside Bruffey-Hills Creek Cave. Most of the tagged fishes were creek chub, Semotilus atromaculatus, and green sunfish, Lepomis cyanellus. The overall recapture rate was 2.6% as only three of 117 fishes were recaptured. Forty-nine days was the longest time of residence by two L. cyanellus and one S. atromaculatus, and movement of 83.4 m was observed only for the creek chub. Tag loss was confirmed as one factor in the low recapture rate. Nine species of fishes were collected in the cave, including Phoxinus oreas and Pimephales promelas, two species never collected in a cave. Most of the fishes were pigmented normally, but many creek chubs were depigmented and appeared white or pigmentless when first observed in the cave stream. Four species, Phoxinus oreas, Pimephales promelas, Ameiurus nebulosus, and Lepomis macrochirus, were collected for the first time in Bruffey-Hills Creek Cave and in the Bruffey and Hills creeks drainage. Although data from this study did not shed light on residence time of fishes in the cave, the consistent occurrence of epigean fishes in this cave was shown. A list of epigean fishes from caves worldwide was included along with a discussion of aspects of the ecology of epigean fishes in caves and of evolution of troglobitic fishes.     

Carcass feeding as a cryptic foraging mode in round goby Neogobius melanostomus

Round gobies Neogobius melanostomus were observed readily consuming soft tissue from carcasses of larger fishes under both laboratory and field conditions. Consumption normally progressed in a typical sequence, starting with soft and easily accessible tissues such as the eyes, followed by puncture of the abdominal cavity, gut consumption and then muscle consumption. Carcass feeding has not previously been seen in N. melanostomus and has potential consequences for transfer of nutrients and contaminants.     

The response of stream fish to local and reach‐scale variation in the occurrence of a benthic aquatic macrophyte

1. The aquatic macrophyte Podostemum ceratophyllum has been shown to increase stream productivity, abundance and biomass of benthic invertebrates, and local occurrences of some stream fishes. However, experimental evidence that fishes preferentially associate with Podostemum is lacking, and the value of Podostemum as a predictor of stream fish assemblage composition has not been studied. 2. We conducted two short‐term (2 week), small‐scale (36 m²) experimental manipulations of Podostemum cover in the Conasauga River (Georgia and Tennessee, U.S.), and found higher abundances of benthic insectivorous fishes in patches with augmented (>80%) compared to reduced (7%) Podostemum cover. In an observational study, we quantified associations among percent cover of Podostemum, fish species richness, land cover, shoal length and base‐flow turbidity at 20 randomly selected shoals from a 39‐km reach that spanned a gradient of decreasing forest land cover. 3. Richness of all fish species and of lotic fishes peaked in the centre of the study reach, and richness was weakly correlated with predictor variables. Occupancy models for individual species also indicated that longitudinal position was a strong covariate for 13 of 19 species examined, with little support that Podostemum cover influenced occupancy. 4. Local associations may reflect choices by benthic fishes to utilise Podostemum, whereas downstream decline in fish species richness and Podostemum cover may reflect altered capacity of the system to support native species.     

Grazing by the intertidal fish Anoplarchus purpurescens upon a distasteful polychaete worm

Synopsis Cirratulid worms are common inhabitants of the central California rocky intertidal zone and appear to offer a potentially rich source of food for intertidal fishes. However, analyses of stomach contents revealed that they do not appear in the diets of the commonest intertidal fishes. Apparently only one species, the eel blenny Anoplarchus purpurescens, feeds on cirratulids in significant amounts.Feeding experiments employing local intertidal fishes showed that the common intertidal cirratulid, Cirriformia luxuriosa, is distasteful to most of the fishes. Only two species ate its tentacles, and only A. purpurescens consistently ate large quantities. We propose that C. luxuriosa possesses a predation-deterring chemical similar to that reported in C. spirabrancha, although A. purpurescens apparently has been able to circumvent this anti-predator mechanism.The ability of A. purpurescens to eat Cirriformia tentacles allows it to tap a seemingly little-used food source, and thus may decrease competition between A. purpurescens and other intertidal fishes. This feeding relationship also represents a possible example of coevolution between a predator and its prey.     

An assessment of mitochondrial variation in Arctic gadoids

Climatic changes during the quaternary history in Arctic regions have shaped the genetic variation and genealogies of Arctic species. Several studies have been conducted in recent years on genetic diversity of Arctic organisms, but marine fishes are largely underrepresented in these studies. Here, we present a study on mitochondrial variation in three Arctic gadoids: Arctic cod (Arctogadus glacialis), Greenland cod (Gadus ogac), and Polar cod (Boreogadus saida). In addition, geographic variation in Polar cod is presented. The sequence variation at the mtDNA presents similar patterns as observed for other related marine fishes. Variation in these three species reflects rather different historic processes, due to colonization and climatic changes than differences in life histories. In Polar cod, a deeper genealogy is observed and variation is dependent on both latitude and longitude. The deep genealogy indicates either admixture of separate lineages or a population, which has been stable in size during alternating cold and warm periods of the pleistocene. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Moon phase influences the diet of southern Ray's bream Brama australis

Diet composition of the southern Ray's bream Brama australis was examined from stomach contents of 399 specimens sampled by bottom trawl on Chatham Rise to the east of South Island, New Zealand, over 3 years. Prey items were predominantly mesopelagic fishes and crustaceans. Multivariate analysis indicated that moon phase explained more of the diet variability than any other predictor examined. It appears likely that diet composition is influenced by a combination of changes in both tidal flows and illumination. Different combinations of prey were consumed by B. australis at different times of the lunar cycle. An influence of moon phase on feeding by fishes has rarely been reported, but it is likely that moon phase influences the diets of other species that specialize in mesopelagic prey. The most important prey group by mass for B. australis was Myctophidae (primarily Lampanyctodes hectoris), followed by Stomiiformes (primarily Maurolicus australis) and shrimps (Sergestes spp). An ontogenetic shift in diet was observed, from numerical dominance by small crustaceans including amphipods and euphausiids (with some fishes) in smaller (mass <1045 g) B. australis to pelagic teleost prey (with a few larger crustaceans) in larger (>1440 g) B. australis.     

Genomic organization of duplicated short wave-sensitive and long wave-sensitive opsin genes in the green swordtail, <Emphasis Type="Italic">Xiphophorus helleri</Emphasis>

Background  

Long wave-sensitive (LWS) opsin genes have undergone multiple lineage-specific duplication events throughout the evolution of teleost fishes. LWS repertoire expansions in live-bearing fishes (family Poeciliidae) have equipped multiple species in this family with up to four LWS genes. Given that color vision, especially attraction to orange male coloration, is important to mate choice within poeciliids, LWS opsins have been proposed as candidate genes driving sexual selection in this family. To date the genomic organization of these genes has not been described in the family Poeciliidae, and little is known about the mechanisms regulating the expression of LWS opsins in any teleost.     

Influence of Trophic Relations on Form and Behavior Among Fishes and Benthic Invertebrates in Some California Marine Communities

Study of interactions among fishes and benthic invertebrates off southern California's Santa Catalina Island showed the great extent to which taxa are defined by trophic relations. The dominant fishes there are acanthopterygian teleosts, with the serranine serranid Paralabrax clathratus morphologically nearest the evolutionary mainstream. Because mainstream species have morphologies similar to their progenitors, marine communities have a long history of adaptations to threats from generalized predators like P. clathratus. Species examined at Santa Catalina indicate this experience has produced four basic defenses: smallness, which presents difficulties for predators with large and simply constructed feeding mechanisms; dissemblance, as through camouflage, which makes detection by visual hunters difficult; inedibility, which is attained by incorporating materials that an unspecialized digestive system cannot accommodate; and nocturnality, which results in avoiding diurnal predators altogether. Examination of trophic relations among the major fishes in Santa Catalina communities shows each with specialized ways to counter these defenses. Prey smallness has been met by reducing size of mouth relative to size of prey, either by evolving as smaller fishes or through structural changes in head and jaws. Prey dissemblance has been accommodated through enhanced visual acuity and varied means to remain an unrecognized threat while waiting for prey to move. Inedibility has been countered by developing specialized features of the alimentary tract, including dentition, while adjustments to nocturnality have included enhanced sensory capabilities that detect prey in low light. These adaptations to prey defenses define varied lines of divergence from the teleost mainstream as represented atbreak Santa Catalina.     

Morphologic and genetic variability in the Barbus fishes (Teleostei,Cyprinidae) of Central Italy

Italian freshwaters are highly biodiverse, with species present including the native fishes Barbus plebejus and Barbus tyberinus that are threatened by habitat alteration, fish stocking and invasive fishes, especially European barbel Barbus barbus. In central Italy, native fluvio‐lacustrine barbels are mainly allopatric and so provide an excellent natural system to evaluate the permeability of the Apennine Mountains. Here, the morphologic and genetic distinctiveness was determined for 611 Barbus fishes collected along the Padany–Venetian (Adriatic basins; PV) and Tuscany–Latium (Tyrrhenian basins; TL) districts. Analyses of morphological traits and mitochondrial DNA sequence data explored the natural and anthropogenic factors that have shaped their distribution ranges. Over 100 alien B. barbus were recorded in the Tiber basin (TL district) and Metauro basin (PV district). Comparisons of genetic and morphometric data revealed that morphometric data could identify alien B. barbus from native Barbus, but could not differentiate between B. tyberinus and B. plebejus. Genetic analyses revealed ~50 D‐loop mtDNA haplotypes and identified a distinct Barbus lineage present only in the Vomano River at the southern boundary of PV district. Demographic expansion and molecular variance analyses revealed a lack of geographic structuring across the sampling regions. While the contemporary B. plebejus distribution has been driven primarily by anthropogenic fish translocations, the dispersal of B. tyberinus has been via natural dispersion, including their crossing of the Apennine Mountains via temporary river connectivity. The results also revealed that the Barbus fishes of the mid‐Adriatic region of Europe have a complex pattern of local endemism. To conserve these patterns of genetic uniqueness, especially in the mid‐Adriatic basins, Barbus fishes should be managed by treating them as unique evolutionary units and ceasing translocations of all Barbus fishes between river basins.     

Nutrient recycling by two phosphorus-rich grazing catfish: the potential for phosphorus-limitation of fish growth

In ecosystems where excretion by fish is a major flux of nutrients, the nitrogen (N) to phosphorus (P) ratio released by fish can be important in shaping patterns of algal biomass, community composition, primary production, and nutrient limitation. Demand for N and P as well as energy influences N/P excretion ratios and has broad implications in ecosystems where nutrient recycling by fishes is substantial. Bioenergetics and stoichiometric models predict that natural fish populations are generally energy-limited and therefore N/P recycling by fishes is relatively invariant. Yet, the potential for P limitation of growth has not been examined in herbivorous fishes, which are common in many aquatic habitats. We examined N/P excretion ratios and P demand in two P-rich herbivorous catfishes of the family Loricariidae, Ancistrus triradiatus (hereafter Ancistrus) and Chaetostoma milesi (hereafter Chaetostoma). Both fishes are common grazers in the Andean piedmont region of Venezuela where we conducted this study. Mass balance (MB) models indicate that these fishes have a high P demand. In fact, our Ancistrus’ P MB model predicted negative P excretion rates, indicating that Ancistrus did not consume enough P to meet its P demand for growth. Direct measurement of excretion rates showed positive, but very low P excretion rates and high N/P excretion ratios for both taxa. To obtain measured P excretion rates of Ancistrus from the MB model, gross growth efficiency must be reduced by 90%. Our results suggest that growth rates of both of these herbivorous and P-rich fish are likely P-limited. If P limitation of growth is common among herbivorous fish populations, herbivorous fishes recycle likely at high N/P ratios and act to diminish the quality of their food.     

What are the characteristics of lionfish and other fishes that influence their association in diurnal refuges?

In Caribbean reefs, the lionfish Pterois volitans is an invasive species that causes severe negative ecological effects, especially as this crepuscular predator consumes very diverse prey. Lionfish are not active during the day and stay in their refuges, sharing these spaces with various other fishes. The aim of this study is to determine which fishes are associated with the lionfish in their shelters, and what characteristics of both the invasive and native species may influence and explain such coexistence between a predator and its potential prey. Through diving and snorkelling, we visited 141 lionfish refuges, mostly caves, where we observed 204 lionfish and 494 other fish from 16 native species. We recorded species and abundance, as well as lionfish size and abundance. Half of the lionfish were observed in groups and the majority were large-sized. The association with most fish species seems fortuitous, but three species, Gramma loreto, Chromis cyanea and Canthigaster rostrata, were frequently observed in association with lionfish. Numerous fish juveniles, most likely Scarus coeruleus, were also observed together with the invasive predator. The more commonly associated fishes, particularly G. loreto, are mostly associated with large-sized lionfish that were found in groups. The associated fishes are also generally found in groups. Gramma loreto is a potential cleaner of the lionfish; the reasons for the association between these fish species and the invasive lionfish may be more complex than a simple predator-prey relationship and are discussed based on their biological traits and previously reported lionfish trophic ecology and predation behaviour.     

The locomotory system of pearlfish Carapus acus: What morphological features are characteristic for highly flexible fishes?

The body curvature displayed by fishes differs remarkably between species. Some nonmuscular features (e.g., number of vertebrae) are known to influence axial flexibility, but we have poor knowledge of the influence of the musculotendinous system (myosepta and muscles). Whereas this system has been described in stiff‐bodied fishes, we have little data on flexible fishes. In this study, we present new data on the musculotendinous system of a highly flexible fish and compare them to existing data on rigid fishes. We use microdissections with polarized light microscopy to study the three‐dimensional anatomy of myoseptal tendons, histology and immunohistology to study the insertion of muscle fiber types into tendons, and μ‐CT scans to study skeletal anatomy. Results are compared with published data from stiff‐bodied fishes. We identify four important morphological differences between stiff‐bodied fishes and Carapus acus: (1) Carapus bears short tendons in the horizontal septum, whereas rigid fishes have elongated tendons. (2) Carapus bears short lateral tendons in its myosepta, whereas stiff‐bodied fishes bear elongated tendons. Because of its short myoseptal tendons, Carapus retains high axial flexibility. In contrast, elongated tendons restrict axial flexibility in rigid fishes but are able to transmit anteriorly generated muscle forces through long tendons down to the tail. (3) Carapus bears distinct epineural and epipleural tendons in its myosepta, whereas these tendons are weak or absent in rigid fishes. As these tendons firmly connect vertebral axis and skin in Carapus, we consider them to constrain lateral displacement of the vertebral axis during extreme body flexures. (4) Ossifications of myoseptal tendons are only present in C. acus and other more flexible fishes but are absent in rigid fishes. The functional reasons for this remain unexplained. J. Morphol., 2012. © 2011 Wiley Periodicals, Inc.     

Trophic level scales positively with body size in fishes

Aim The existence of a body size hierarchy across trophic connections is widely accepted anecdotally and is a basic assumption of many food‐web models. Despite a strong theoretical basis, empirical evidence has been equivocal, and in general the relationship between trophic level and body size is often found to be weak or non‐existent. Location Global (aquatic). Methods Using a global dataset for fishes ( http://www.fishbase.org ), we explored the relationship between body size and trophic position for 8361 fishes in 57 orders. Results Across all species, trophic position was positively related to maximum length (r²= 0.194, b= 0.065, P < 0.0001), meaning that a one‐level increase in trophic level was associated with an increase in maximum length by a factor of 183. On average, fishes in orders that showed significantly positive trophic level–body size relations [mean = 51.6 cm ± 11.8 (95% confidence interval, CI)] were 86 cm smaller than fishes in orders that showed no relation [mean = 137.1 cm ± 50.3 (95% CI), P < 0.01]. A separate slopes model ANCOVA revealed that maximum length and trophic level were positively correlated for 47% (27 of 57) of orders, with two more orders showing marginally non‐significant positive relations; no significant negative correlations were observed. The full model (order × body size) explained 37% of the variation between body size and trophic position (P < 0.0001). Main conclusions Our results support recent models which suggest that trophic level and body size should be positively correlated, and indicate that morphological constraints associated with gape limitation may play a stronger role in determining body size in smaller fishes. Differences among orders suggest that the nature of the trophic level–body size relation may be contingent, in part, on evolutionary history.     

Long-term stability of the seasonal succession of different zooplankton species in a brackish water lagoon (southern Baltic Sea)

While it has been widely suggested that freshwater fishes from East Asia invaded the western Palaearctic, details about this process are largely unknown. Here, using the cytochrome b gene, we evaluated the phylogenetic relationships of a small group of Eurasian primary freshwater fishes (Cobitidae), which are widely distributed and species rich in East Asia and Europe, with the purpose of inferring their invasion process of Europe from East Asia. Though phylogenetic relationships of cobitids were not well resolved, our analysis could identify three sister groups formed by the European and East Asian cobitids, which brought new insights into the biogeography of the genera Cobitis, Misgurnus, and Sabanejewia. The present results support the view that Asian cobitid fishes may have invaded Europe at least five times independently, and once reverse colonization of European cobitids to East Asia could also be found. Ancestral Sabanejewia might have been the first cobitids to cross Siberia and invade the EMZS (Euro-Mediterranean zoogeographic subregion) about 33.54 million years ago (MYA). One lineage of Cobitis and the ancestor of Misgurnus fossilis (Linnaeus) almost in the same time invaded the Europe, responding to 16.71 MYA and 16.59 MYA, respectively. Three different lineages of Cobitis were found to have invaded the EMZS from East Asia, and once reverse invasion to East Asia occurred to one subclade of European Cobitis. And our data also suggest that the diversity of East Asian cobitid fishes, especially of the genus Cobitis, is greatly underestimated. Handling editor: C. Sturmbauer     

Host range of Achlya orion Coker & Couch on certain freshwater fishes

By the present investigations the host range of Achlya orion Coker and Couch has been extended to, Puntius sophore, Puntius ticto, Puntius conchonius, Puntius sarana, Chanda ranga, Channa marulius, Channa punctatus, Notopterus notopterus, Labeo rohita, Colisa lalia and Anabas testudineus; 11 freshwater fishes.The ability of certain Saprolegniaceous fungi to parasitise fish has been reported by several investigators viz., Clinton (2), Tiffney (21, 22), Tiffney & Wolf (23), Gopalakrishnan (3), Vishniac & Nigrelli (24), Scott & O'Bier (7), Bhargava et al (1) and Srivastava & Srivastava (10.20) etc. These fungi are known to attack fish eggs, fry, fingerling and adult fishes and as a general rule the fungal infection starts when the host gets injured either mechanically or as result of infections other than fungal which often result in epidemics causing 100% mortality of the infected hosts (Scott & O'Bier 7).During the course of an investigation on fungi associated with fish diseases, author observed the severe fungal infections of Colisa fasciatus (Bl.) and Anabas testudineus (Bl.) in the waters of Ramgarh Lake, Gorakhpur, causing heavy mortality of the infected hosts. The fungus was identified as Achlya orion Coker Couch and its pathogenicity was also established by conducting laboratory inoculation experiments on the lines of Scott & O'Warren (8); (Srivastava & Srivastava, 14).In view of the above observations, it seemed desirable to investigate the host range of this mould on accurately identified hosts in order to asses the extent of damage done to such fishes.     

The lipid compositions of high-Antarctic notothenioid fish species with different life strategies

Lipid and fatty acid compositions of five notothenioid fishes from the Antarctic Weddell and Lazarev Seas were investigated in detail with regard to their different modes of life. The pelagic Aethotaxis mitopteryx was the lipid-richest species (mean of 61.4% of dry mass, DM) followed by Pleuragramma antarcticum (37.7%DM). The benthopelagic Trematomus lepidorhinus had an intermediate lipid content of 23.2%DM. The benthic Bathydraco marri (20.8%DM) and Dolloidraco longedorsalis (14.5%DM) belonged to the lipid-poorer species. Triacylglycerols were the major lipid class in all species. Important fatty acids were 16:0, 16:1(n-7), 18:1(n-9), 18:1(n-7), 20:5(n-3) and 22:6(n-3). The enhanced proportions of the long-chain monounsaturated fatty acids, 20:1 and 22:1, in the lipid-rich pelagic fishes clearly reflected the ingestion of the two copepod species, Calanoides acutus and Calanus propinquus, which are the only known Antarctic zooplankters rich in these fatty acids. Although wax esters are the major storage lipid in many prey species, they were absent in all notothenioid fishes studied. Thus, wax esters ingested with prey are probably converted to triacylglycerols via fatty acids or metabolised by the fishes. The enhanced lipid accumulation with increasingly pelagic lifestyle has energetic advantages, especially with regard to improved buoyancy. It is still unknown to what extent these lipids are utilised as energy reserves, since it has been suggested that not only the benthic but also the pelagic Antarctic fishes are rather sluggish, with a low scope for activity and hence low metabolic requirements. Accepted: 14 May 2000     

Fecundity of the freshwater catfishes mystus seenghala (sykes), mystus cavasius (ham), wallagonia attu (bloch) and heteropneustes fossilis (bloch) from the plains of Northern India

Fecundity of four species of catfishes, namely, Mystus seenghala (Sykes), Mystus cavasius (Ham), Wallagonia attu (Bloch) and Heteropneustes fossilis (Bloch), was studied. The fecundity of Mystus seenghala and Mystus cavasius varied between 20064 to 46443 and 3314 to 63135 respectively. In Wallagonia attu and Heteropneustes fossilis it varied between 66070 to 453148 and 1375 to 46737 respectively. In all the four species fecundity has a linear relationship with body weight and gonad weight, and a parabolic relationship with length in all the fishes excepting Mystus seenghala, where it is linear. By subjecting the data to multiple regression analysis, it is observed that the fecundity of each species can be most accurately determined by taking two variables together. In all the fishes studied the relative fecundity (Egg/body wt.) does not change significantly either with length or body weight.     

Ecology of Listeria monocytogenes and Listeria species in India: the occurrence,resistance to biocides,genomic landscape and biocontrol

Listeria monocytogenes, the causative agent of listeriosis, has been implicated in increasing foodborne outbreaks worldwide. The disease is manifested in various forms ranging from severe sepsis in immune-compromised individuals, febrile gastroenteritis, still birth, abortions and meningoencephalitis. In India, data from studies on the detection and molecular epidemiological analysis of L. monocytogenes are only recently emerging. The presence of Listeria in different ecological niches has been recorded from India, including foods, soil, vegetables, mangrove swamps, seafood, freshwater fishes, clinical cases, and also insects. The organism has also been isolated from women with spontaneous abortions, miscarriage or recurrent obstetric history, aborted foetuses, animal clinical cases and wildlife samples. A novel species of Listeria has also been characterized. Listeria monocytogenes strains isolated from clinical, environmental, and foods showed biofilm-forming abilities. Listeria monocytogenes serotype 4b isolates of ST328, a predominant and unique ST observed in India, was repeatedly isolated from different sources, times, and geographical locations. Here, we reviewed the occurrence of Listeria in different sources in India, its resistance to biocides, and provide epidemiological analysis on its genomic landscape.     

A new record of Iranian subterranean fishes reveals the potential presence of a large freshwater aquifer in the Zagros Mountains

A new locality is reported for the Iranian subterranean fishes Garra typhlops and Garra lorestanensis (and probably Eidinemacheilus smithi), near the village Tuveh in the Dez River drainage. The site is 31 km straight‐line distance away from the only other known locality where these species have been observed previously. The finding suggests the presence of a sizeable subterranean aquifer system in the Tigris drainage extending for between 31 and 162 km.