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The relationship between some habitat factors and fish assemblage was analyzed in the Taleghan River, Alborz Province, Iran. Fish specimens from thirty-three sites were sampled by electrofishing device in October 2014. The habitat parameters, including elevation (m), water depth (cm), river width (m), river slope (%), current velocity (m.s -1), number of large stone (> 15 cm), average stone diameter (cm), substrate index (SI%), level of potamal cover, level of periphyton cover, pH, electrical conductivity, total dissolved solid and temperature (°C) were measured in all sampling sites. Canonical correspondence analysis was performed to study the relationship between fish assemblage and environmental factors. The results showed that the fish assemblages of the Taleghan River are organized by the environmental variables. Based on the results, the abundance of C. gracilis did not show any distinctive relationship with examined habitat variables, whereas the presence and abundance of B. cyri showed a rise with increasing substrate index and bed stone diameter and a decline with increasing river width and flow velocity. The presence and abundance of O. bergianus rises with the increasing current velocity and river width and showed a decline with increasing slope, depth and substrate index. The results of this study provides insights into the ecology of fishes in the Taleghan River and can help an effective fisheries management of other rivers of the Caspian Sea basin.

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]

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.