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In this study phylogenetic relationship of the Jajrud River Brown trout Salmo trutta L. 1758 in the Namak Lake basin was analyzed using complete D-Loop sequence of the mitochondrial genome, compared to other Iranian populations of the species. The results clarified that Jajrud brown trout, similar to other Iranian brown trout populations belongs to the Danube phylogenetic lineage. The observed haplotype in the Jajrud population is similar to the reported haplotype in the Karaj River. Based on the results the Namak Lake basin brown trout affined to the Caspian populations and its relationship to Salmo macrostigma was not confirmed.  Since the Karaj and Jajrud River haplotypes have not been observed in the Caspian Sea basin and because of its relationship to other Iranian and Danube haplotypes it is plausible to consider this haplotype as an old haplotype that also may exist in the Caspian Sea basin. According to the biology of Brown trout, geographic characteristics, and based on the properties of the Namak haplotype it may be inferred that the Namak Basin Brown trout populations are native to the basin and are not introduced.

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The cave barb habitat is located in a Karst formation along the Sezar River. The springs on the walls of the Sezar River valley may provide a means for fish in surface waters to penetrate into the underground waters. These observations propose the probability for a migratory relationship between Garra gymnothorax in the Sezar River and the cave barbs (Garra typhlops and Garra lorestanensis). In addition, a variety of different body shapes including fusiform and slender body forms are observed among the cave fish. This phenotypical variation may be a sign of an unknown genetic diversity or could be attributed to the variable environmental conditions in different parts of the subterranean habitat. To clarify the situation, we used the sequences of mtDNA cytochrome oxidase subunit I and next generation sequencing method. The results showed that the fusiform and slender body shapes of G. typhlops and G. lorestanensis were not different with regard to their mtDNA and genomic compositions. Moreover, the analysis of the genomic their mtDNA and genomic compositions. Moreover, the analysis of the genomic showed that a limited level of gene flow (less than 3%) from G. gymnothorax probably existed in G. thyphlops. The low level of gene flow may be related to the lower fitness and adaptability of the surface dwelling fish to the subterranean life conditions.