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Reproductive characteristics of Mossul bleak, Alburnus mossulensis, a native species of Cyprinidae family in Bibi-Sayyedan River of Semirom, Isfahan, were investigated by monthly sampling during December 2010 to December 2011. Five hundred and fourty three specimens (256 females, 159 males and 31 immature) were caught by a sein net (5 mm mesh size). The collected sampeles were anesthesized in 1% clove oil solution and transported to the laboratory on ice and subjected to dissection and biometric measurments. Age of males and females ranged from 0+ to 5+ years. The sex ratio was 1M: 2.2F (p < 0.05). The females outnumbered the males in all age classes. The largest female was 16.8cm in total length and 49.12g in weight and the largest male was 14.1cm in total length and 28.19g in weight. The age and total length at first maturity of females and males were estimated as 1 year and 5.3cm total length, and 2 years and 4.4cm, respectively. The minimum, maximum, and avarge absolute fecundity were 2064, 10316, and 5505 ± 2686, respectively and also the relative fecundity was 203 ± 58 egg/g body weight. Macroscopic analysis of gonads and gonadostomatic index values suggested that spawning of A. mossulensis occurs from March to June with a peak in April. Thus, A. mosullensis is considered a group-synchronous type species with a capacity for multiple ovulations within a reproductive season (multiple spawner).

The reproductive biology of the Iranian cichlid, Iranocichla hormuzensis Coad, 1988, was investigated for 13 consecutive months in lower Mehran River, from August 2008 through August 2009. Four hundred and eighty six individuals (252 males and 234 females) were captured using a seine net (5 mm mesh size). The observed sex ratio was 1M: 0.93F (χ², df = 1, P = 0.414). Mean ± SD of total length (TL) values in males and females were 70.34 ± 8.16 and 62.08 ± 6.51 mm, respectively. The frequency of 56-65 mm size class was higher in females and the 66-75 mm size class in males. A gonadosomatic index (GSI) analyses of females indicated that the reproductive period was during February-June, with a peak in March. Fecundity was best correlated with total body mass (M) (linear regression, r^2 = 0.62) condition factor (linear regression, r^2 = 0.62) and total length (TL) (linear regression, r^2 = 0.56). The absolute fecundity ranged between 48-167 eggs with a Mean ± SD of 107 ± 35.2. Egg diameters ranged from 0.58 to 2.93 mm.

The genetic structure of the genus Alburnus is not well known and the phylogenetic relationships among its species are uncertain. In the present study, simple sequence repeats (SSRs or microsatellites) were used to evaluate genetic diversity and genetic differentiation between Alburnus mossulensis Heckel, 1843 from Kashgan River in Lorestan province and A. caeruleus Heckel, 1843 from Gamasiab River in Kermanshah province. Thirty specimens from each species were collected and their genomic DNA was extracted. Polymerase chain reaction was performed using four pairs of SSR markers, including CypG24, BL1-2b, BL1-98 and Rser10, from which a total of 480 bands were amplified. The average observed and expected heterozygosities for both species were similar. In both species, except for Rser10 locus, all loci deviated from the Hardy-Weinberg equilibrium (P < 0.05). Average genetic distance and Fst values between the two species were 0.361 and 0.04, respectively. Analysis of molecular variance (AMOVA) revealed more interspecific (94%) than intraspecific (4%) genetic variation. Although four sets of SSR markers developed for other cyprinids showed high level of polymorphisms in the Iranian bleaks, they showed low genetic differentiation between them. Study on the possibility of genetic differentiation of the examined species by more microsatellite loci or other molecular markers such as amplified fragment length polymorphisms (AFLP) are recommended.

Length-weight and length-length parameters were calculated for seven fish species belonging to five families in the Zohreh River, Iran. The weight-length relationships were estimated using the equation W = aLb. The b values varied between 2.72 and 3.33, with a mean ± SD of 2.88 ± 0.28. The b values parameter in the length-weight relationship equations were calculated as 3.15 for Alburnus mossulensis Heckel, 1843; 3.78 for Barilius mesopotamicus Berg, 1932; 2.86 for Cyprinion macrostomum Heckel, 1843; 2.89 for Nuchequula gerreoides (Bleeker, 1851); 2.80 for Mastacembelus mastacembelus (Banks & Solander, 1794); 2.72 for Liza abu (Heckel, 1843); and 3.19 for Paraschistura nielseni (Nalbant and Bianco, 1998). This study presents the first LWR and LLR references for these species in the Zohreh River. [ABSTRACT FROM AUTHOR]

Karyotype of the smallmouth lotak, Cyprinion kais Heckel, 1843 (Cyprinidae) was investigated by examining metaphase chromosomes. This study is the first karyological survey on this vulnerable fish species in the Tigris-Euphrates basin. The results can be used for population studies, management and conservation programs. The fish were caught by electrofishing from Godarkhosh River in Ilam province, western Iran, in April 2008 and transported live to the Ichthyology Laboratory of Isfahan University of Technology. Five fish were injected intraperitoneally with two doses of phytohemagglutinin (PHA), 4 μg g-1 bw with a 20-h interval to induce cell divisions. After 8 h in 20°C water, the fish were injected intraperitoneally with colchicine (25-50 μg g-1 bw) to depress cell divisions in the metaphase stage and left for 7 h before sacrificing. Kidney and gill epithelia were used for karyotype analyses. It was determined that C. kais has 2n = 50 chromosomes, consisting of 8 metacentric, 7 submetacentric, 3 subtelocentric and 7 telocentric chromosome pairs. Centromeric index, arm ratio and Fundamental Number (FN) were determined as 0-50, 1-∞, and 86, respectively. The shortest and longest chromosome was a telocentric and a submetacentric one, with 2.61 and 6.88 μm length, respectively. [ABSTRACT FROM AUTHOR]

The study describes the length-weight and length-length relationships for three cyprinid species, namely Barbus lacerta, Squalius lepidus and Pseudorasbora parva, and a balitorid species, Oxynoemacheilus angorae from the Sirwan River (located in Kurdistan and Kermanshah provinces, Iran. This study presents the first reference on LWR for most of the species in their distribution range. [ABSTRACT FROM AUTHOR]

We assessed the distribution of alien fishes in the Karun River Basin, Iran. Fish were collected from 39 sites during the November-December 2018 low-flow period. In total, 39 fish species from nine orders and 14 families were documented. Among these, 10 species were alien to the basin (986 individuals; 15.7%). Four species were the most abundant alien species and primarily in impounded, downstream reaches. Redundancy analysis (RDA) was conducted to identify the extent of changes in alien fish assemblages with environmental parameters. RDA1 and RDA2 accounted for 36.24% and 25.33% of the variation of alien species, respectively. Altitude, depth, electrical conductivity, water temperature, turbidity, dissolved oxygen, and river width were the most significant parameters affecting alien species distributions. We present a dual-pathway cause-and-effect hypothesis proposing that alien fish species presence causes declines in the ecological status of native fish communities. We then explore how human-induced aquatic ecosystem degradation creates opportunities for alien species to invade new ecosystems, further impacting native fish communities. Our study contributes insight into the cause and effect of the presence of alien fish species in the Karun River Basin and emphasizes the urgency of conservation measures to protect this critically endangered watershed., Competing Interests: Conflicts of Interest: The authors declare no conflict of interest.

Large river systems are one of the most important water resources for human societies. However, the ecological integrity of large rivers has been altered greatly by human activities. To monitor and manage these ecosystems, multimetric indices (MMI) are considered as efficient tools. This study aimed to develop and validate a fish-based multimetric index for the Karun River basin, Iran (Karun fish-based multi-metric index [KFMMI]). Eighteen rivers and 54 sites in the basin were sampled in July-August 2019, and physico-chemical and habitat characteristics were used to identify reference sites based on principal components analysis (PCA). Of the 54 sites, 14, 26, and 14 sites were classified as least, moderate, and most disturbed sites, respectively. Fifty-four candidate metrics were evaluated for range, responsiveness, and redundancy with other metrics. This resulted in the identification of eight metrics (relative abundance of native and endemic taxa, relative richness of migratory taxa, relative richness of Leuciscidae taxa, relative richness of herbivorous taxa, relative abundance of cyprinid taxa, relative richness of vegetative inhabitant taxa, relative abundance of slow water flow, and relative richness of edge inhabitant taxa) that informed on species richness and composition, migratory status, functional feeding groups, and habitat preferences. The KFMMI showed excellent performance in separating least, moderate, and most disturbed sites in our study area. Regarding water quality, the KFMMI was classified 16, 5, and 29 sites as good, moderate, and bad, respectively. The discrimination efficiency of KFMMI was 81.6%, which makes it an effective management tool for directing restoration actions at most disturbed sites and intensifying protection of least disturbed sites.

A physical, chemical and biological characterization of river systems is needed to evaluate their ecological quality and support restoration programs. Herein, we describe an approach using water chemistry, physical structure and land use for identification of a disturbance gradient existing in the Karun River Basin. For this purpose, at each site, physical structure and physico-chemical data were collected once in each season for a total of 4 samples during the period (October 2018 - September 2019). Principal components analysis (PCA) of 17 variables identified five variables that were influential across all seasons: conductivity, total habitat score, stream morphology, clay & silt, and sand. Of the 54 sites, 14, 26 and 14 sites were classified as least, moderate and most disturbed sites, respectively. The metric Ephemeroptera, Plecoptera and Trichoptera (EPT) taxa was used for validation of the classification. Results in different seasons showed that all the least disturbed sites (n=14) were significantly different from moderate and most disturbed sites (p < 0.01). In this study the validation process presented a good confirmation of a priori reference sites selection process, showing that the proposed criteria could be considered as appropriate tools for characterization of the existent disturbance gradient in the Karun River Basin.

Garra hormuzensis, new species, is described from the Kol River drainage. It is distinguished from its congeners in the Iranian part of the Persian Gulf basin by having 7 branched dorsal-fin rays, usually 9+8 branched caudal-fin rays, the breast, belly and back in front of the dorsal-fin origin covered by scales, and a free lateral and posterior margins of the gular disc. It is further characterised by having a minimum K2P distance of 1.16% to G. mondica in the mtDNA COI barcode region.

Variation among complete cytb sequences (1140 bp) of Aphanius mesopotamicus Coad, 2009 was compared with closely related species, to investigate the validity of this taxon as a newly-described tooth-carp based on morphological characteristics. Maximum likelihood and Bayesian likelihood trees supported the monophyly of A. mesopotamicus and its sister group relationship to A. sophiae. Some 10-16 differences were found when compared to four different population samples of A. sophiae, whereas, intraspecific differences were only up to 6 bp. These distances suggest divergence from a common ancestor with A. sophiae at roughly 1 million years ago. These results are congruent with morphology-based hypotheses, indicating a recent speciation event.