A new killifish species, Aphanius isfahanensis, is described from the Isfahan basin of Iran. It is distinguished from the other Iranian species of Aphanius by adult color pattern, molecular character states of mitochondrial DNA sequence data, and in multivariate morphometric and meristic space. Based on the phylogenetic analysis of molecular sequence data, the new species is hypothesized to be sister taxon to A. sophiae plus A. persicus, which also occur in Iran.

A zoogeographic analysis of the freshwater fish fauna of Iran based on the distribution of 164 species in 19 basins shows the existence of two major faunas, one influenced by the Caspian Sea basin, the other by the Tigris River basin. A new South basin is proposed, combining three basins in south-eastern Iran.

The most northerly and easterly population of tooth-carps in Iran is described. This isolated population in the Damghan basin of the Alborz Mountains is unique in colour pattern of females but other characters show overlap with populations 560–700 km to the south. Its specific distinction cannot be affirmed on current data but the population is open to human impacts and should be conserved until further studies can be carried out.

The siah mahi, Capoeta fusca, is a sub-endemic fish of eastern Iran. We studied morphometric characteristics, diet and reproduction of 600 specimens in qanats of the central zone of Birjand County, South Khorasan Province, from November 2006 to October 2007. The mean total length was 13.5±1.43 cm and maximum length was 21.5 cm. The length-weight relationship of this fish was described by body weight=0.0101×total length^2.9477 (r²=0.9747). The mean relative length of the gut was 4.42 ± 0.48, suggesting that this species is an herbivorous fish. Similarly, the mean of the vacuity index was 30.95±5.90, and this fish was classified in a relatively gluttonous group. Besides plants as the primary food, molluscs, aquatic insects, and sometimes frog eggs were distinguished as secondary foods. According to the gonadosomatic index, the reproduction period begins in March and lasts into May. Variations of the gastrosomatic index show that feeding is correlated with reproduction. Measurement of salinity resistance in 96 fish showed that this species can withstand up to 10 p.p.t. of salinity indefinitely.

A new species of Chondrostoma is described from Iranian part of the Tigris river drainage. This species differs from other species of the genus Chondrostoma in Iran and Euphrates-Tigris river drainage by a combination of characters, including lack of a horny blade on lower jaw; arched mouth; 8 branched dorsal-fin rays (9 in holotype), and 10 branched anal-fin rays; 51 – 58 lateral line scales, 8 – 9 scales above the lateral line, 5 – 6 scales below the lateral line and short, 14 – 16 circum-peduncular scales, and 15 – 17 gill rakers along the entire gill arch.