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Reproductive characteristics of Aphanius isfahanensis, an Iranian endemic Cyprinodontid fish in the Zayandehrud River were examined. Samples were taken monthly, from June 2016 to May 2017. Some 485 specimens (245 females, 240 males) were caught by a hand net. Age of males and females ranged from 0+ to 2+ years. The largest female and male in total length and weight was 5.36 cm, 2.39 g and 4.49 cm, 1.56 g, respectively. The overall sex ratio was 1 M:1F (p > 0.05). The highest mean gonadosomatic index in females and males was in May (19.19), and July (3.77), respectively. Oocyte diameter ranged from 0.12 to 1.40 mm, and monthly mean oocyte diameter were significantly different (P < 0.05). The minimum, maximum, and average absolute fecundity was 7, 250 and 120 ± 5SD, respectively. The relative fecundity was 90 ± 30 egg/g body weight. Macroscopic analysis of gonads and gonadosomatic index (GSI) values showed that spawning of A. isfahanensis occurs from April to July with a peak in May and June. Aphanius isfahanensis is a group synchronous spawner and produces more than one oocyte clutch in a single reproductive season. [ABSTRACT FROM AUTHOR]

We studied the feeding ecology of an endemic cyprinodontid fish, Aphanius marassantensis (Kızılırmak Toothcarp), with special emphasis on seasonal and ontogenetic diet shift. The dietary composition revealed an omnivorous diet with great seasonal and ontogenetic variation. Cladocera and Calanoid Copepods (Diaptomus sp.) dominated the diet in Spring and Summer, whereas the food items of plant origin e.g. filamentous algae and diatoms were the most important components in Autumn and Winter. An ontogenetic diet shift was also demonstrated. While the feeding of juveniles was based mostly on planktonic organisms, adult individuals preferred larger prey taxa, such as Gammarus sp. and Gastropods. There was no significant sex-related variation in feeding with the exception for the volume of gut content. The investigation on the feeding strategy of A. marassantensis suggested a generalised feeding pattern with some specialised individuals. This generalist feeding habits may account for the well-established population of this species in a big reservoir under coexistence of two non-native fish species, Pseudorasbora parva and Atherina boyeri. [ABSTRACT FROM AUTHOR]

Otolith morphology in the tooth-carp/killifish genus Aphanius is a source of informative taxonomic characters at both the species and population level. Most work on otoliths has focused on adult specimens, while evidence of ontogenetic variation is rarely provided. In this study we describe the development of otolith morphology during the early life stages of an endangered and endemic species, the Fars tooth-carp Aphanius farsicus from southern Iran. The study material comprises 34 larvae and early juveniles representing nine different developmental stages (0-120 days post hatching), all reared under the same laboratory conditions. The results reveal (i) a significant correlation between standard length and otolith size (length) in larval and early juvenile stages, (ii) clear differences in otolith morphology between larvae/early juveniles and adults, and (iii) a temporal link between the appearance of the sulcus on the otolith’s inner face and the emergence of the dorsal and anal fins. Our results indicate that otoliths of Aphanius can be recognized as originating from larval or early juvenile fish based on their short rostrum and antirostrum lengths and wide excisura, in addition to their small size. These immature otoliths are, however, not diagnostic at the species level in A. farsicus, nor most probably in other species of tooth-carp. The outcome of our study is also of interest to palaeontologists working with fossil killifish otoliths, as it can help avoid misinterpretation of ancient species diversity. [ABSTRACT FROM AUTHOR]

Trophic ecology is essential to understand ecosystem functioning and structure and assist biological conservation. Here we investigate, for the first time, the feeding ecology of Aphanius farsicus, a cyprinodontid fish endemic of a single landlocked river basin in central Iran. We sampled monthly a population of this fish species during a year and examined differences in food across seasons, sexes and sizes. Similarly to other cyprinodonts, A. farsicus showed sexual dimorphism and more abundance of females. Size structure and individual condition varied across seasons, with larger fish in spring and better condition in summer and less in winter. We found no empty guts, suggesting that these fish feed all year round due to the warm climate of its native distribution. Farsi toothcarp diet was based on detritus, algae (particularly diatoms, green algae, and cyanobacteria), and small invertebrates. Seasonal variation in diet was more important than variation due to fish size and the Farsi toothcarp consumed more green algae in spring and early summer and more diatoms and insects the rest of the year. Herbivory was considerable, similarly to a few other cyprinodonts, and increased with fish size, particularly because of higher consumption of green algae. As with species composition in diet, season was more important than size in the variation of number, biovolume, mean size, and diversity of prey captured, with higher number, richness and size of prey captured in summer. The ontogenetic diet shift was less marked in this cyprinodont than in many other Aphanius species, probably due to its reduced size and the resource availability of its habitat, but was also shown by size-dependent feeding selectivity for a few invertebrates. [ABSTRACT FROM AUTHOR]

Aphanius Nardo, 1827 (Actinopterygii, Cyprinodontidae) is a widely distributed genus in the Mediterranean and Persian Gulf area and includes several endangered species. The otolith morphology in Aphanius is known to represent a valuable tool for the taxonomy, and is also indicative for the genetic diversity of a particular population. The present study focuses on the otoliths of the endangered A. ginaonis (Holly, 1929), which is endemic to the Geno hot spring in southern Iran. The taxonomic status of A. ginaonis has repeatedly been questioned, and some scholars have argued that it merely represents a morphological variation of the widespread A. dispar. We present a comparison of the otolith morphology of A. ginaonis (52 specimens) with that of A. dispar (Rüppell, 1828) from the Mehran River Basin (southern Iran) (17 specimens) and an A. dispar population from the Persian Gulf coast of the United Arab Emirates (32 specimens). Our data obtained from SEM pictures, otolith morphometry and statistical analyses suggest that A. ginaonis represents a valid species. In A. ginaonis individuals with a standard length exceeding 23 mm, the otolith variables length–height and rostrum length represent useful complementary diagnostic characters discriminating this species from other Aphanius species. Besides ontogenetic variation, we found extremely high otolith form variability in A. ginaonis, including some otoliths with a morphology distinctly deviating from the basic morphology type. We hypothesize that these variations may be a result of the artificial introduction of A. dispar into the Geno hot spring during the last years and subsequent hybridisation. [ABSTRACT FROM AUTHOR]

In many fishes, individuals prefer to associate with phenotypically similar or conspecific individuals (conspecific cueing). Such phenotypic segregation can be an important evolutionary driver, for example, in intralacustric sympatric speciation processes. I examined conspecific cueing in two species of sympatric pupfish from Laguna Chichancanab in southern Mexico: the little shoaling and highly territorial Cyprinodon beltrani and the highly shoaling but non-territorial C. simus. Females were tested for shoal species preferences in two testing scenarios: (1) a sequential choice test where shoals of four conspecific or four heterospecific ( Cyprinodon sp. or Poecilia reticulata) females were presented in succession, and (2) a simultaneous choice test where female shoals of both Cyprindon species were presented concurrently. Overall, higher shoaling in C. simus was corroborated in this study. In the sequential test, no effect of the type of stimulus shoal (con- or heterospecific) on shoaling behavior was detected. In the simultaneous tests, C. beltrani, but not C. simus females showed a preference for the conspecific shoal. It seems possible that C. simus females did not evolve species recognition mechanisms because no other Cyprinodon species in the Laguna Chichancanab shows equally high shoaling, which automatically leads to the formation of single-species (i.e., C. simus-) shoals. C. simus males do not establish long-term territories, but rather spawn within shoals, whereas C. beltrani females approach males in their breeding territories to spawn. I discuss that this behavioral difference still provides a powerful reproductive isolation mechanism even in the absence of conspecific cueing in C. simus. [ABSTRACT FROM AUTHOR]

Sound production in reproductively active sheepshead minnows, Cyprinodon variegatus, is documented. Male sheepshead minnows produced acoustic signals in seven behavioral contexts including: patrolling the territory, chasing, hovering on the territory, courting, fighting, spawning, and during the startle response. Fifty eight percent of the calls contained one or two pulses and 44% of the calls were greater than three pulses. With the exception of differences in frequency the structure and behavioral contexts of C. Variegatus calls is similar to the calls of C. bifasciatus. [ABSTRACT FROM AUTHOR]

The Andalusian toothcarp, Aphanius baeticus, is a critically endangered cyprinodontid species, with only nine known extant populations. Although not yet studied in the field, the distribution and abundance of Andalusian toothcarp are thought to be strongly influenced by interspecific interactions. We analysed the abundance and microhabitat use of Andalusian toothcarp in two water courses, one in which several other fish species occurred (sympatric site) and one hypersaline stream in which toothcarp was the only species present (allopatric site). Fish were sampled using plastic minnow traps and results were analysed separately for three size categories. Toothcarps were clearly more abundant in the allopatric population than in the sympatric one, though the difference was less apparent in the smallest size category. In coexistence with other species, toothcarp occupied shallower microhabitats, but in both sites in the absence of shelter fish selected deeper positions than in its absence. While in the sympatric site sheltered microhabitats were used predominately by small individuals, in the allopatric ones they were used by larger ones. Observed patterns strongly suggest that predation is the main mechanism involved in the differences in abundance and microhabitat use between sites. Our results confirm that the presence or absence of coexisting species is an important habitat feature for Andalusian toothcarp populations. [ABSTRACT FROM AUTHOR]

We evaluated the effects of dissolved oxygen on offspring survival, parental costs, and the pattern of parental care in Florida flagfish, Jordanella floridae (Cyprinodontidae). Specifically, we quantified (1) embryonic development and survival in the absence of parental care, (2) behavior of non-reproductive adults, and (3) behavior of parental males across a gradient in dissolved oxygen. Embryo developmental rates and survivorship increased with dissolved oxygen, with a relatively sharp increase in survival between medium and high oxygen treatments. Non-reproductive adults increased their frequency of aquatic surface respiration, reduced overall activity, and increased opercular beat rate as oxygen declined, suggesting increased costs of activity with reduced oxygen. Taking these cost measures together, costs appear to increase slowly as oxygen starts to decline and then increase sharply as conditions approach hypoxia. In contrast, parental effort increased gradually with dissolved oxygen. We conclude that the increase in care from low to medium oxygen primarily results from a sharp decline in physiological costs, whereas the continued increase in care from medium to high oxygen primarily results from an increase in offspring value. In addition, our results highlight that the benefits of fanning for offspring are not well understood and that they may increase with oxygen, contrary to what has been previously assumed. [ABSTRACT FROM AUTHOR]

Many estuarine habitats are characterized by episodes of hypoxia, the frequency and severity of which may vary seasonally. Accordingly, resident fish species may show seasonal differences in their capacity to tolerate hypoxia. We have tested this hypothesis in the gulf killifish, Fundulus grandis, sampled from the Lake Pontchartrain estuary (Louisiana) at different times of the year. We measured 2 indicators of hypoxia tolerance, the frequency of aquatic surface respiration (ASR) during gradual reduction in dissolved oxygen (D.O.) and survival time during severe hypoxic stress, and found both to be significantly affected by season. Fish collected during the summer did not engage in ASR until the D.O. concentration dropped to values lower than that required to elicit ASR by fish collected during other seasons. Laboratory acclimation of fish to low oxygen did not change the relationship between ASR behavior and D.O., suggesting that the observed seasonal effect on ASR was not simply due to previous exposure of summer fish to environmental hypoxia. Furthermore, fish collected during the summer and winter had significantly longer survival times during exposure to severe hypoxia than fish collected during the fall. Survival analysis indicated that the condition of fish was positively associated with survival time, and seasonal variation in condition accounted for about half of the observed difference between survival times of fish collected during the summer and fall. Seasonal variation in ASR and survival, when taken together, demonstrate that hypoxia tolerance in F. grandis may be subject to acclimatization. An increase in hypoxia tolerance during the summer could increase survivorship of fish when exposed to elevated temperatures and low oxygen concentrations which prevail during the summer months. [ABSTRACT FROM AUTHOR]

Sound production in Cyprinodon bifasciatus, a pupfish endemic to the Cuatro Ciénegas basin, Coahuila, México, is documented. The average dominant frequency is 409 Hz, with an average duration of 55 msec. Calls were produced by males during pursuits of conspecifics and cichlids, during territory patrol, while following a female and after spawning. There are differences in call structure between contexts, especially postspawn calls versus pursuit and courtship calls. There may be differences between sites, especially Mojarral Oeste versus Becerra and Churince. Given sound production in this species of Cyprinodon and the related genus Fundulus, it is possible that sound production is more widespread than previously thought in Atherinimorpha. In addition, this is another documentation of sound production in a clear freshwater species indicating that sound production is widespread in clear freshwater fish. [ABSTRACT FROM AUTHOR]

Allozyme electrophoresis was used to assess temporal genetic variation in three successive generations of the Mediterranean killifish, Aphanius fasciatus. Samplings were carried out in 1995, 1996 and 1997 in a brackish-water habitat at Elba Island, Italy and a total of 212 specimens were collected. The five loci for which polymorphism has been detected in a previous study were assayed. Mean expected heterozygosity values [H=0.397 (SE 0.077), H=0.336 (SE 0.092) and H=0.313 (SE 0.092) in 1995, 1996 and 1997, respectively] were not significantly different by ANOVA test. Deviations from Hardy–Weinberg equilibrium were minimal, with only one out of the 15 probability tests showing a significant departure from the equilibrium; whereas genotypic linkage disequilibrium was not detected. Values of Nei's genetic distance were lower than 0.04. Temporal genetic variation in the A. fasciatus population at Elba Island was observed, with F-statistics indicating significant genetic divergence among samples (θ=0.035, SE 0.027, p<0.001). Genetic drift acting on two loci (GPD-1* and LDH-3*) is presumably the main force determining the temporal genetic heterogeneity observed; however, the occurrence of selection on individual loci and/or sampling error cannot be excluded. The observed allelic variation among generations in a single population of A. fasciatus is much less than levels observed among geographically discrete samples in previous studies. [ABSTRACT FROM AUTHOR]

Predator/prey behavior has important consequences for individual survival and recruitment into fish populations, both of which can he affected by stressors such as environmental contaminants. The degree to which prey capture or predator avoidance abilities of a predator or prey species are affected will determine the direction in which the balance will be shifted. In a contaminated estuary we have studied, prey capture and predator avoidance of resident mummichogs, Fundulus heteroclitus, are impaired, which may account for individuals in that estuary having reduced growth and longevity compared with those from uncontaminated sites. Exposure to sediments, water, and grass shrimp from the contaminated site can impair the predatory abilities of mummichogs from a clean site. An important prey species, the grass shrimp, Palaemonetes pugio, has a greater population density and a greater proportion of large individuals at the polluted site, apparently because of reduced predation pressure. Mummichog larvae at the polluted site are initially more active and better at prey capture and predator avoidance than larvae from clean sites, but later they become poorer at both. Differences in predator vulnerability among larvae appear to he due to population differences in behavior, which may be due in part to both genetic and environmentally-caused factors. Conservation of fish populations should consider fish behavior and its interaction with contaminants. [ABSTRACT FROM AUTHOR]

Egg size alone is a poor and misleading variable in life-history studies. A mathematical technique for estimating yolk and blastodisc volume ratios in fishes, a much more meaningful character, is generated from first principles. The technique is demonstrated with an example of early ontogeny in fishes of the genus Lucania (Pisces: Cyprinodontidae). Wild, adult rainwater killifish, Lucania parva, and bluefin killifish, L. goodei, were collected in Florida and transported to the laboratory, where offspring were reared under controlled conditions. Offspring were sampled at the onset of cleavage, for simple measurements of yolk and blastodisc morphology. Application of mathematical equations allowed estimates of yolk and blastodisc volumes in the two species. No significant differences were found in clutch size, blastodisc volume, or egg density; however, significant differences existed in the absolute yolk investments, and blastodisc : yolk volume ratios. These differences in reproductive investment within the genus Lucania are interpreted by the altricial-precocial life-history model as a possible causal mechanism in the evolution of species within this genus. The mathematical equations presented in this study enabled us to partition reproductive investment into components that are more biologically meaningful than simple `egg size'. [ABSTRACT FROM AUTHOR]

Five samples (30 individuals each) of the Mediterranean cyprinodontid fish, Aphanius fasciatus, were analysed by allozyme electrophoresis for a study concerning genetic structure and gene flow among populations. Forty-three loci, twelve of which were polymorphic at P0.99 level, were analysed. A. fasciatus showed low levels of genetic polymorphism, with expected heterozygosity values ranging from 0.027 (SE = 0.013) to 0.064 (SE = 0.023). The modified Rogers' genetic distances ranged from 0.053 to 0.202. The observed pattern of genetic differentiation among populations, obtained by multidimensional scaling of the modified Rogers' genetic distances, was consistent with geographic distribution. Coancestry coefficient (θ - 0.302, SE = 0.045) indicated a very high degree of genetic subdivision among populations and the estimate of gene flow (the effective number of migrants per generation. Nm = 0.445), computed by Wright's method, showed very restricted gene flow among populations. The regression analysis carried out using log-transformed values of geographic distance against ...(pairwise values of Nm) gave a regression coefficient, b = -1.03, indicating that a restricted migration rate among populations can occur according to the one-dimensional stepping-stone model. The amount and modality of gene flow in A. fasciatus inferred from the results of the present study are consistent with the absence of dispersal stages and with the fragmented nature of brackish-water habitats along the coasts. [ABSTRACT FROM AUTHOR]

This article describes the Killifish (Orestias ascotanensis Parenti, 1984) (Cyprinodontidae) one of the threatened fishes of the world. This fish is listed on the Chilean Endangered Species List.. Its features are described in detail and it is compared with other similar species. The authors discuss the species' entire range and population distribution restricted to springs of the Ascotian salt lake. They also describe how the fish utilizes various habitats during different seasons. The fish’s diet is described as is the environmental conditions it prefers or tolerates. The fish’s life-cycle and spawning behavior are described and threats including increased water salinity are listed together with conservation actions and recommendations.

The article presents information on Conchos pupfish. Cyprinodon eximius is listed as threatened by the Texas Parks and Wildlife Department and as threatened by Mexico. Cyprinodon eximius can be distinguished by the caudal fin on mature males having black spots on the interradial membranes and the caudal fin bar being relatively wide preceded by a clear band. The species is one of a complex of 12 pupfish species inhabiting what was a once extensive Pleistocene body of water in the Chihuahuan Desert. Reproductive characteristics for this species have not been documented. Conchos pupfish inhabit environments with limited amounts of water that are facing increasing threats from a growing human population.

This article presents information related to Fundulus julisia, one of the threatened fishes of the world. Commonly called Barrens topminnow it is considered endangered by the state of Tennessee. The Barrens topminnow has been successfully bred in captivity and is currently being introduced into areas in the Barrens Plateau region with help from private organizations, several state and federal agencies, and co-operative landowners. Conservationists recommend that wild populations should be closely monitored to ensure the survival of the species.

The article presents information on the endangered species of fish, Cyprinodontidae. Males possess a unique speckled color pattern and all individuals have a relatively streamlined body shape. Groundwater pumping caused the type locality, to go dry in 1954 and that population is extinct. The other population is restricted to the Balmorhea spring complex and three artificial refugia, all near Balmorhea, Texas. This habitat is highly unnatural, ephemeral and wholly dependent upon local irrigation practices and otherwater-use patterns.

The article presents information related to the threatened fishes of the world, with special reference to the species cyprinodon bovinus, commonly known as the leon springs pupfish. This species of fish no longer exists due to impounding and ground-water pumping. This species was extirpated from Leon Springs as early as 1938 and presumed extinct. Its population size in Diamond Y Draw is estimated to be less than 10000 adults. Continued monitoring of population and genetic structure is warranted. Further releases of pupfish from Dexter National Fish Hatchery would help to insure a natural genetic structure in nature.

The article presents information on the fish, Cyprinodon tularosa. The common name of these type of fishes is White Sands pupfish. White Sands pupfish is sexually dimorphic. Adult males have a black terminal band on the caudal fin and display bright yellow-orange coloration on paired fins and outer margins of anal and dorsal fins. The side is grayish blue and the back and upper parts metallic blue. Females are whitish to silvery with vertical side bars which are grayish to golden and have an ocellus on posterior base of dorsal fin. Upper parts and back are olivaceous. White Sands pupfish are threatened due to their limited distribution. Current threats to these habitats and their populations include the introduction of non-native fishes, de-watering and chemical contamination .

The article presents information on a fish species fundulus lima that is an endangered species. Its common names are Baja killifish, San Ignacio killifish and Sardinita peninsular. Although, there are no quantitative evaluations of the abundance of this species before the introduction of exotic fishes to the oases, current monitoring along its historic range has revealed low relative abundance of this native killifish as compared to exotic species. Since this killifish is one of only three known freshwater taxa endemic to Baja California peninsula, its very limited distribution merits considetarion at least as threatened.

The article presents information on cyprinodon laciniatus, a rare fish. The bodies of water that this species inhabits are brackish with salinities ranging from 10-14 ppt. The bottom is marl over limestone in the form of coarse cobble and boulders. Algae, chiefly Batophora are abundant. Transect studies reveal the greatest abundance of individuals to be within 10 m of the shore at depths ranging from 0.3 to 1.2 m. Although feeding studies have not been done, the Bahama pupfish is probably similar to the sheepshead minnow in consuming mainly plant matter and detritus. The differences in dentition between the two species suggest some feeding specializations, however. Reproduction: Although studies on the reproductive biology of C. lacinicitus have not been done, fecundity measurements of several populations of Gyp rinodon from New Providence have been performed. Total number of eggs produced closely correlates with size of the individual and ranges from 20 to 250 eggs per ovary. The presence of eggs at different stages of maturation indicates that spawning takes place throughout the year.