morphometric

Fish are a significant component of the aquatic environment and are crucial insupporting and maintaining the entire ecological system, thereby making freshwater systemsmore resilient and sustainable.The structure of a fish community is influenced bybiotic interactions and abiotic variables. In recent years, spanning from thelast 5 to 10 years, conservationists and commercial fishermen have reporteda significant declinein freshwater fisheries. The decline can be attributed to several factors, includingthe introduction of exotic species, construction of dams, anthropogenic activities, illegal fishing, and overfishing. Schizothorax richardsonii, is a highly valued freshwater fish, inhabiting the foothills of the Himalayan regions. The declines of S.richardsoniiin the Himalayan region are more than 90% in some areas and the predicted overall reduction is inferred to be around 50% with similar rates. Withstanding all the variations in biotic and abiotic factors, the species is expanding its range of altitude and evolving according to the climate-driven shifts in the Himalayas and apparently, its current distributional range would be lost over time. In Indo-Himalayan ranges, there is a lack of conservative measures and as a result, despiteits ecological importance, snow trout has been given a vulnerable status by IUCN 2020. This review aims to provide descriptive biology and discuss the anthropogenic impact on the population structure of snow trout and its conservation.

Mudskippers (Oxudercidae) are euryhaline fish found in mudflats, sandy beaches, and mangrove swamps. Owing to the high abundances of mudskipper species in Peninsular Malaysia, the identification process is found challenging. The purpose of this study was to identify selected species of mudskipper from selected mangroves in Terengganu, east coast of Peninsular Malaysia according to morphometrical variations and development of key pictorial of mudskipper. A total of 63 mudskippers were collected using a fish net in Marang (n= 30) and Setiu (n= 33). Quantitative data on the morphometric characteristics of each individual were identified namely Periophthalmus gracilis, P. variabilis and P. argentilineatus. One-way analysis of variance showed significant differences (P<0.05) in 10 out of 16 morphometric characteristics among the three species. In the casewise statistics analysis, 92.1% of the mudskippers were correctly classified into their original groups on average. The canonical variate analysis (CVA) scatter plot showed the segregation of three identified mudskipper species into three distinct groups. In the cluster analysis, UPGMA dendrogram indicated the segregation of the three species into two distinct clades, and P. gracilis and P. variabilis were included in the sister group, whereas P. argentilineatus was in a separate clade. The development of the key pictorial of mudskippers showed that 10 species from five genera were successfully recognized and distinguished by comparing their body parts as key indications. This study will be helpful to researchers acquiring information for identifying mudskippers especially from the genus Periophthalmus.

In the Hadhramout coast, the Gulf of Aden, six substantiated records fish species were recorded for first time. Review of all previous studies and publications show that these species from different families were not previously reported in the Gulf of Aden. The species identified include Parascolopsis eriomma(Nemipteridae), Kyphosus vaigiensis(Kyphosidae), Sargocentron rubrum(Holocentridae), Coryphaena equiselis(Coryphaenidae), Argyrosomus japonicus(Sciaenidae) and Scarus nigar(Scaridae). This paper describes the detailed characteristics of each species.

This study documents the occurrence of the exotic Suckermouth armoured catfishes (Loricariidae) of the genus Pterygoplichthysspp. in the Sri Lankan reservoirs. As little is known about the taxonomic status of the alien Pterygoplichthys spp. in Sri Lankan inland waters, this study was conducted based on the specimens collected in four distinct reservoirs in Kala Oya basin, North central province of Sri Lanka. The different morphometric measurements and meristic counts of current study reveals that suckermouth armored catfish, previously reported as Pterygoplichthys multiradiatus (Orinoco sailfin catfish), actually belong to the two different species-Pterygoplichthys disjunctivus (Vermiculated sailfin catfish) and Pterygoplichthys pardalis(Amazon sailfin catfish). Although the current examination describes two different species as above, some wild populations may probably be hybrids. In recent past there is a high concern on these species due to rapid range expansion and the effects on native ichthyofauna and inland fisheries resources. Therefore, implementations of effective management options of these species are highly recommended in native condition.

During surveys of the Hadhramout coast, the Gulf of Aden, five fish species were recorded. Review of all previous studies and publications show that these species from different families were not previously reported in the Gulf. The species identified include Lepidocybium flavobrunneum (Gempylidae), Muraenesox cinereus (Muraenesocidae), Conger macrocephalus (Congridae), Histiopterus typus (Pentacerotidae) and Brotula multibarbata (Ophidiidae). This paper describes the detailed characteristics of each species

The present study was aimed to investigate sexual dimorphism in morphometric and meristic characters of three carangid species Carangoides ferdau, Carangoides malabaricus, and Gnathanodon speciosus from the Red Sea, Egypt. The basic statistics of the morphometric indices (relative to SL or HL) of the three carangid species considered sexual dimorphism in C. ferdau, C. malabaricus, and G. speciosus regarding some indices that are size-free and valid as a discriminating tool between males and females of the examined species. The type of size allometry of males and females of the three studied species was estimated according to the bivariate concept. No sexual dimorphism was observed in the meristics characters. Additional features should be investigated to determine sexual dimorphism to facilitate the identification for conservatory purposes and correct management.

Homaloptera gymnogaster (Family: Balitoridae) is an endemic freshwater fish in Sumatra, Indonesia that can be found up until a high elevational aquatic body. There is no previous report about a thorough study on its morphological variations from its various populations. In this study, 47 individuals H. gymnogaster were collected using random sampling from five different elevations (Sikai River at 1996, 1552, 1420, Batang Gumanti on 1531, and Matur River on 1097 m asl), on which 53 morphological characters measured. The result indicated that 41 characters significantly varied with the Kruskal-Wallis test (P<0.05%), which consist of 29 morphometric and 12 meristic characters. The MannWhitney U test (with <0.05% standard confidence) confirmed the high differentiation on morphometric and meristic characters among the study sites. The Principal Component Analysis (PCA) plot hinted that albeit populations in Sikai River divided come from different elevations, were still categorized as the same group. On the contrary, Batang Gumanti and Matur River site separated into different groups. This study concluded that differentiation of morphological characters on H. gymnogaster was influenced by current velocity and river size.

This study was conducted to investigate the morphological variation between seven populations of Oxynoemacheilus seyhanensis inhabiting three basins of Turkish inland waters. For this purpose, a total of 71 specimens were collected from Yildizeli, Taşköprü, Suşehri rivers (Kizilirmak basin), Büyükpotuklu, Pinarbaşi and Örenşehir rivers (Seyhan basin) and Akdağmadeni River (Yesilirmak basin). A total of 31 morphometric characteristics were measured. After standardization, data were analyzed using one-way ANOVA and Duncan, Kruskal-Wallis tests, principal component analysis (PCA), canonical variate analysis (CVA), non-parametric MANOVA and cluster analysis. The results showed significant differences in 26 traits between the studied populations of O. seyhanensis (P<0.05) revealing a high morphological flexibility of this deep-bodied species.

The Sexual dimorphism (SD) in body size is very common among the scorpions. In this study, the SD was investigated in two aspects of size and shape in the genus Odontobuthus Vachon, 1950 as a small genus of the family Buthidae. This genus has six fossorial species of which four are distributed in Iran. For this purpose, 43 morphometric variables, consisting of 38 metric measurements and five meristic characters were digitized in the six species, O. bidentatus, O. doriae, O. tavighiae, O. tirgari, O. sp.1 and O. sp.2. The results show that Sexual Size Dimorphism (SSD) were significant in three species: O. doriae, O. tavighiae and O. sp.2. While O. sp.1 represented a SD for more aspects of shape, O. bidentatus did not show a significant SD for all studied traits. The amount of SD in size and shape were not the same in different species. The results showed that males have larger metasoma than females even when they are pulled to the same size. Having larger metasoma may correspond to a more efficient performance during mating, predation or combat with other males, so it should be under a high sexual selection. Type II ANOVA showed a significant interaction between species and sex for shape, but not for size. It suggests that the evolution of SD for size has been in parallel for all studied species, while it has been in different directions for shape. Among meristic variables, only the number of pectin denticles were sexually dimorphic, with males having more denticles than females in all studied species.

Morphological variation of Alburnus mossulensis (Heckel, 1843) populations in Iran were investigated by collection of 705 specimens from 27 rivers of five basins, including Bushehr, Fars, Karkheh, Karun and tributaries of Tigris (Diyala) basin in Iran in 2010 by a seine net. The specimens were fixed in 10% formalin for further investigation after anesthetizing in 1% clove oil solution. Twenty-two morphometric and 11 meristic characters were examined. Morphometric characters in adjusted form and meristic characters in classified form were used for population comparison. Analysis of morphometric and meristic characters by ANOVA showed significant differences (p<0.05) in all basins for all characters except the number of dorsal and anal fin spines. Classification of meristic characters showed most specimens of all basins have eight soft rays in dorsal fin, 12 soft rays in anal fin, 19 soft rays in caudal fin, 15 soft rays in pectoral fin and nine soft rays in pelvic fin. Discriminant function analysis showed that populations from Fars and Karun Basins were different from each other and from other populations, on the other hand, populations from Diyala, Karkheh and Bushehr basins overlapped. This result may indicate that there are similar conditions in Diyala, Karkheh and Bushehr basins, resulting in more similarity amongst the populations of these basins.