---

Aims: In the present study, the morphometric and meristic traits of Alburnus chalcoides from the Chelvand (Astara), Khalesara (Talesh), Siahdarvishan (Anzali wetland), Sefid and Pol (Guilan Province), Tonekabon and Babol (Mazandaran Province) rivers were compared.
Materials & Methods: For this purpose, a total of 170 specimens were collected from above-mentioned rivers. In the Lab some 39 morphometric and 10 meristic traits were recorded. All data were analyzed by using One-Way ANOVA, Duncan test, Kruskal-Wallis, principal component analysis (PCA), canonical variate analysis (CVA) and cluster analysis.
Finding: The results showed a significant difference in 36 morphometric and five meristic traits among the studied populations. CVA result separated the studied populations in the southern parts of the Caspian Sea basin. Also, cluster analysis placed the Chelvand River population in a distinct clade. 
Conclusion: This study showed high diversity of morphometric compared to meristic traits and better performance of these traits in population's distinction.

---

The aim of the present study was to identify the phytoplankton species which producing domoic acid and okadaic acid toxins in coastal waters of Banar Abbas city, and to determine the concentration of domoic acid and okadaic acid toxins in water and shellfish samples.Water sampling was performed in winter 2015 and summer 2016 from coastal areas overlooking the discharge of municipal and industrial effluents. Shellfish were collected from the coasts of Bandar Abbas and Bandar-e- Lengeh. Phytoplankton toxins were measured by kit method and instrumental analysis based on ELIZA method.Pseudonitzschia delicatissima, Pseudo-nitzschia pungens and Pseudo-nitzschia seriata were identified in the production of domoic acid, while Dinophysis caudate and Prorocentrum Lima were recorded as okadaic acid producers in the coastal waters of Bandar Abbas. Water-soluble okadaic acid showed significantly higher concentrations than domoic acid. Instudied shellfish samples (Circenita callipyga, Barbatia candida, Telescopium telescopiumandThalessa savignyi), the measured concentrations of okadaic acid ranged from 59.8 ± 2.38 to 121.96 ± 28.25 μg / kg. This value for domoic acid was from 0.85 to 83.59 ± 38.72 μg / kg.Compared to the guideline values, the observed concentrations of okadaic acid and domoic acid toxins in the studied shellfish were lower than the allowable level.  But this value was recorded for the water-soluble domoic acid above the allowable value, which requires continuous monitoring to achieve the quantitative and qualitative pattern of phytoplankton toxins in order to support the safety of the marine ecosystem users in Hormozgan province.

---

The present study was conducted in Electric Blue Cichlid Sciaenochromis fryeri in early larval developmental stages from the fifth day post hatching (DPH) until 51 DPH to determine day of transforming from embryo to juvenile. Morphological characteristics were evaluated by using ImageJ software. Allometric growth patterns were calculated based on the formula Y=aX^b. Yolk sac depletion was occurred on day 9. Scales were developed on day 19 and finaly developed juvenile shape. allometric pattern of different body segments were calculated according to isometry, positive, and negative allometry. Positive allometry of head and tail prior to inflexion point and variation in allometric growth pattern in different body segment determine priorities of organogenesis for survival in fish early life history. The obtained results showed consistency between the larval morphological changes and development of organs related to sensory movements and larval behavior. Every morphological change in larvae displays the development and evolution of one of the organs involved in feeding, breathing, swimming and sensory organs.

---

The aim of the present study was to estimate growth and mortality parameters and length-weight relationship of Barilius mesopotamicus populations in difrent Iran basins. For this purpose, 460 fish specimens from Diala, Jarrahi, Karun, Karkheh and Bushehr basins and subbasins, including Zardmashin, Aalaa, Jarrahi, Dez, Shur, Meymeh, Changooleh, Kangir, Doyrej, Ahram, Zohreh, Kheirabad, Karzin, Shahpur and Darolmizan rivers, were sampled. Total length, fork length and standard length were measured by a digital caliper (cm) and total weight by a digital scale (g). Also, some scales were prepared and studied for age determination. The length-weight relationships showed that population from Bushehr, Jarahi, Karun and Dila, had negative allomeric growth pattern while Karkheh population had an isometric growth pattern. The highest estimated total length and weight was 9.2 cm and 5.4 g. Age of the fish was between 0⁺ and 2⁺. The highest asumptetic total length was observed in Diala basin with Bertallanfy equation of L_t= 9.22[1-e^-1.3(t+0.07)]. The condition factor was about 0.5. Considering body indices, Bushehr, Jarahi, Karun and Diala had a better condition, and Karkheh population had a lower index, probably indicating a poorer condition in this river.
 
 

---

In this study, the morphological variation of Oxynoemacheilus bergianus was studied in the different rivers of the Namak Lake and Caspian Sea basins using traditional morphometric method. For this purpose, a total of 76 specimens were collected from eight river systems and after fixation into 4% buffered formalin, transfered to the laboratory, a total of 31 morphological characteristics were measured using digital calipers. After standardization, the morphometric data were analyzed using multivariate analysis including principal component analysis (PCA), canonical variate analysis with p-value obtained from MANOVA (MANOVA/CVA) and cluster analysis (CA). The results showed significant differences in 24 traits between the studied populations (P<0.05), which anal fin depth and the ventral-anal fin distances were main discriminative ones. CVA analysis was able to separate the studied populations. Also, CA placed the Gharesu and Sefid populations in a clade and separate from other populations. The observed differences may be related to phenotype plasticity in response to environmental conditions.

---

This study was conducted to investigate the morphological variation of Planiliza abu in the Tireh (Tigris Basin), Kor (Kor River Basin) and Jegin (Hormozgan Basin) rivers using traditional (TM) and geometric morphometric (GM) methods. For this purpose, a total of 62 specimens were collected using electrofishing device and Salik net. In the Lab, 21 morphometric traits were measured. Then, to extract the morphological data in the geometric method, 16 landmark-points were defined and digitized on the photographs taken from the left side of fish using tpsDig2 software. The results showed that the studied populations had significant differences in 7 morphometric traits (P<0.05). The differences in the geometric method were those of the head size, body depth, pectoral fin position and caudal peduncle length. Based on the results, GM method showed higher accuracy to reveal the morphological variations in the generalist species of Planiliza abu, which can inhabit a wide range of habitats.

---

In this study, the morphometric and meristic characteristics of Psettodes erumei in two regions of Bandar Abbas and Bandar Jask were investigated. Up to30 Psettodes erumei fish were prepared from each region and after performing bioassay operations, 29 morphometric characteristics and 9 meristic characteristics were measured and counted. According to the results, the average coefficients of variation in the morphometric characteristics of right-handed and left-handed fish in Bandar Abbas region are 0.34 and 0.41, respectively, and the average coefficient of variation of meristic factors of right-handed and left-handed fish is 0.14 and 0.17. The mean coefficients of variation of morphometric factors of right-handed and left-handed fish of Bandar Jask are 0.25 and 0.24, respectively, and the mean coefficient of variation of meristic factors of right-handed and left-handed fish is 0.10 and 0.10. Also, Psettodes erumei fish had a significant difference in 25 morphometric factors and 1 meristic factor between these regions (P <0.05). The height of the anterior fin, the height of the dorsal fin, the height of the ventral fin on the dark and light surface, the length of the base of the thoracic fin on the dark and light surface and the width of the mouth are the most important morphometric factors. There was no significant difference between the parameters measured in Psettodes erumei fish in any similar area (P> 0.05). According to these results, the differences between the morphometric and meristic characteristics are more pronounced, which is itself due to different environmental conditions in these two regions.

---

The morphometric and meristic traits of the dominant demersal flathead fish P.indicus, G.suppositus, and G.scaber which were caught as by-catch of shrimp (bottom trawl) and also in coastal stake net (moshta), During the period from April 2022 to October 2023, it was evaluated comparative in different age groups. A total 19 morphometric and six meristic characteristics were recorded. The average total length and weight of the fish in P.indicus (23.2 ± 6.9) cm, (99.9 ± 78.4) gr and in G.suppositus species (20.6 ± 4.7) cm, (67.4±33.7) gr and also in G.scaber (18.5±2.9) cm, (31.0±17.2) gr. In the studied species, among all the measured morphometric traits (except head hight, body hight and Eye part head higth), the rest of the traits in P.indicus species have the highest and lowest (except head length and Anal fin hight ) has been observed in G.scaber. In the investigation of meristic traits, the highest and lowest number of gill rakers in G.suppositus and G.scaber, respectively. The number of rays Pectoral fin was the highest in G.suppositus and the lowest in P.indicus.  species.the three studied species in different age groups, showed significant differences in various morphometric and meristic parameters (except for the number of rays of the first dorsal fin) (P<0.05). The three studied species clearly distinguished themselves in the present research. The results of this research showed that the analysis of morphometric and meristic traits is a useful tool for the separation of flatheads species studied in this research.