Iranian Journal of Ichthyology

Invasive vs. endemic cichlid species: A review of Iranian cichlids with new locality records for Oreochromis niloticus and O. mossambicus (Actinopterygii: Cichlidae)

2025-06-08T19:21:42+00:00

Freshwater ecosystems support a remarkable proportion of global biodiversity and offer crucial ecological services and economic value to society. Despite their importance, these water bodies are some of the most threatened on Earth and exhibit great vulnerability to the effects of anthropological-mediated threats including introduction of exotic species. At least 37,000 exotic species have been introduced by human activities beyond their natural range to all regions and biomes of Earth, including remote and isolated environments, and many of them have become established. Freshwater environments harbor approximately 18,915 fish species, accounting for a quarter of all vertebrate biodiversity. However, these species are experiencing declines at rates surpassing those observed in other ecosystems. Among the key drivers of this decline, biological invasions have become increasingly significant. Globally, more than 500 exotic freshwater fish species have established populations after their introduction, making them one of the most frequently introduced taxonomic groups, with significant ecological impacts such as competition with native species, habitat alteration, and the spread of diseases The United States records the highest non-native fish diversity (302 species), followed by Canada (63), Brazil (60), Russia (58), Mexico (56), and China (53). Iran, with 33 alien fish species, comprises 58.9% of the freshwater alien fish species of the Middle East, and this count positions Iran among the countries facing moderate to high biological invasion pressure in its freshwater systems, though fewer than global hotspots like the United States. The fish invasion has contributed to the biotic homogenization of freshwater fish assemblages with profound ecological, health and socio-economic consequences. The present study aims to review endemic and alien cichlids of Iran, providing current taxonomic status, distribution, morphological characteristics, identification key, introduction pathways of alien cichlids, their impacts on native fishes, and documenting first and new locality records of Oreochromis mossambicus and O. niloticus and their hybrids in the Minab River drainage (Makran basin, Hormuzgan). Understanding the distribution patterns of exotic fish species and the factors driving their establishment in specific regions are critical for developing effective management strategies and predicting future invasion risks. This is particularly important in biodiversity-rich countries such as Iran.

Confirmed record of Yellow-dabbled flounder; Laiopteryx novaezeelandiae (Günther, 1862), from the Northern coast of the Persian Gulf

2025-08-16T10:39:43+00:00

Three specimens of yellow-dabbled flounder, Laiopteryx novaezeelandiae (Günther, 1862), were collected in the Iranian coastal waters of the Persian Gulf (Hormuz Island) with the trawl net in winter 2025. The COI gene sequence, in addition to morphometric and meristic characters, was used to confirm identification. The mean genetic distance between the identified COI haplotype (PV719947) and previous records of COI Haplotypes of L. novaezeelandiae in GenBank was 0.03 (p- distance) while the genetic distance among five Citharid species was 0.18-0.25. The phylogenetic tree revealed that the identified haplotype is placed in a monophyletic clade beside other haplotypes of L. novaezeelandiae in GenBank. This study provided the first COI molecular sequence and record of L. novaezeelandiae, from the Iranian coast of the Persian Gulf, and the result could lead to a better understanding of the fish fauna in this area.

Inter-basin geometric morphometric comparison of the North Caucasian Bleak (Alburnus hohenackeri) populations in Iran

2025-09-27T08:39:05+00:00

Abstract
This study investigates inter-basin geometric morphometric variation in populations of the North Caucasian bleak (Alburnus hohenackeri) across four major hydrological basins in Iran (Caspian, Sistan, Harirud, and Tigris). A total of 849 specimens from 23 rivers were photographed laterally, and 13 anatomical landmarks were digitized and aligned using Procrustes superimposition. Multivariate analyses including PCA, CVA, Procrustes distances, Mahalanobis distances, and cluster analysis were conducted. PCA revealed that the first two components explained about 40% of the total shape variation, with major differences related to head morphology, body depth, mouth position, and caudal peduncle structure. Despite extensive overlap among populations, a relative separation of the Sistan population from the others was observed. CVA highlighted this pattern more clearly, showing a stronger distinction of Sistan, while Caspian and Tigris exhibited the greatest similarity and Harirud occupied an intermediate position. Pairwise Procrustes and Mahalanobis distances were all statistically significant (p < 0.001), with the greatest distances between Sistan and the other basins and the smallest between Caspian and Tigris. Cluster analysis confirmed this pattern by placing Sistan in a distinct branch, grouping Caspian and Tigris together, and positioning Harirud intermediately. These findings indicate that environmental heterogeneity and geographical isolation have driven divergent phenotypic adaptations among A. hohenackeri populations. The study highlights the effectiveness of geometric morphometrics for detecting inter-basin population structure and provides insights valuable for biodiversity conservation and freshwater fishery management.