کیوان عباسی

Chondrostoma regium and Chondrostoma cyri belong to the genus Chondrostoma, which are distributed in the Tigris, Isfahan, Kor and Caspian Sea basin and have ecological and sport fishing importance. The main purpose of this study was to investigate the relationship between the fecundity with length, weight and age of the fish species in Gamasiab from Tigris and Aras River and fish sampling was performed in December and March 2008 using cast-net and electro-shocker. The result of the study on 46 female fish in maturity stages 4 and 5 (the previous stages to prepare for spawning) in C. regium showed that the absolute fecundity of 1694 to 10843 (5252.7±2377.1) eggs and the relative fecundity of 58 to 154.2 with an average of 98.9 eggs per grams of female weight. Also, the results of 31 fish samples showed C. cyri absolute fecundity of 5526 to 18145 (11135±3284.6) eggs and the relative fecundity of 84.8 to 162.0 with an average of 113.8 eggs per grams of female weight. Also, the correlation (r2) between absolute fecundity and weight, total length and age was .27, .37 and .17, respectively for C. regium and 0.714, 0.702 and 0.712 were determined for C. cyri. The egg diameter of this species was 0.80- 1.96 with an average of (1.22±.29), Also, for C. cyri, the range was 0.78 to 2.25 with an average of 1.44±0.29 mm.

The migration of fish to the sea requires the ability of osmoregulation to exposure to salinity, and changes in the structure and function of many organs, including the kidney, are involved in the developing this process. In this study, quantitative and qualitative changes in the kidney tissue of Caspian kutum (Rutilus frisii) fingerlings exposed to water salinity in the coastal and estuarine areas of the Caspian Sea were investigated. Three weighing groups 0.5, 1, and 1.5g were treated for 10 days in the three natural environments of the river (freshwater), the estuary (6-7‰), and the coast of the Caspian Sea (11-12‰) in the Kiasher beach area. At the beginning (0h) and end of the experiment (240h), 6 individuals from each weight group in each treatment were caught. After dissecting and separating the kidney tissue, the area and diameter of the glomerulus and Bowman's capsule were measured. The results showed that at the end of the experiment, the size of the kidney tissue indices significantly decreased (P<0.05) with the increase in salinity in all treatments. So that, the extent of this decrease in 1 and 1.5g weight groups was significantly more than the 0.5g group (P<0.05). Qualitative changes, including a decrease in the width of the proximal and distal convoluted tubule after exposure to salinity, were observed in all weight groups. The decrease in the size of the glomerulus in the estuary and coastal environments can be because constant drinking of water in these environments causes enough ions to be provided to the body and there is no need for large glomeruli for filtration. In the present research, two weights of 1 and 1.5g can compromise with the conditions of increased salinity of the environment when released and placed in the estuary and coastal environments of the Caspian Sea.

This research is a part of the studies that have been carried out in line with a research plan in Tajen river since 2020-2021. Sampling was done in 7 study stations, including 1) Sari diversion dam, 2) Mahfroz Mehaleh 3) Panbeh Chole 4) Soteh 5) Farah Abad 6) after dam outlet 7) river estuary. The purpose of this research is to investigate the identification, distribution and diversity of fish species and their abundance in different sampling stations. A total of 2,454 fish were examined, belonging to 15 families, 25 genera and 28 species were identified, which include the families Acipenseridae, Atherinidae, Clupeidae, Cobitida, Cyprinidae, Gastrosteidae, Gobiidae, Leuciscidae, Mugilidae, Poecillidae, Percidae, Petromyzonida, Xenocyprididae, Acheilognathidae and Syngnathidae. The largest diversity of species belongs to the Leuciscidae. In this research, the species diversity increased from the upstream to the downstream of the river. According to the Brillion,s index (BI), the lowest BI was in station 3 with 1.415 and the highest in station 7 with 2.989. There was a significant difference in terms of BI in different stations (p<0.05). The average Brillion and Shannon indices obtained in the upstream of the rubber dam were much lower than the downstream of the rubber dam, which shows the effects of the dams on fish communities. The results of this research showed that the diversion dam and the rubber dam as one of the physical and man-made factors have been able to affect the diversity of fish species upstream and downstream of the river, so river restoration is necessary in order to restore anadromous fish stocks.

We listed 28 exotic fish species belonging to 22 genera, 15 families and 12 ordersfor Iranian part of the southern Caspian Sea basin, based on published records and specimens collected between 2000 and 2023. Their native distribution ranges, as well as occurrences in the Iranian waters are given, and the presence of four species is recorded for the first time from the region. Two species are new records for the whole country. The family containing the highest number of exotic species is Xenocyprididae(5 species) followed by Cyprinidae (4 species), Mugilidae and Poeciliidae (3 species each), and Salmonidae and Loricariidae(2 species each). Five species were determined to be invasive due to their wide distribution, established populations, and fast dispersal through the region (Gambusia holbrooki, Carassius gibelio, Hemiculter leucisculus, Pseudorasbora parva, and Rhinogobius cheni). Alien fishes have been introduced for a variety of reasons in the region, including ornament, sport, aquaculture, biological control, and by accident.

The Sefidroud River is the largest river in the north of Iran and has a special importance in the survival of Caspian anadromous fish. In this study, the biodiversity and abundance of fish were investigated in eight points of the Sefidroud River and one point on the sea coast from March 2022 to January 2023. There were identified a total of 40 species of fish from various ecological groups; riverine (26 species), migratory (6 species), and estuarine-marine (8 species). The highest and the lowest number of species were observed in the mid-region of the river and the marine area with 21 and 17 species, respectively. The spatial ecological niche was observed for some species such as three Gobiidae species Caspian goby (Neogobius caspius), Caucasian dwarf goby (Knipowitschia caucasica), and Iranian Goby (Ponticola iranicus) occupied the sea coast, the estuary, and the upstream area, respectively. Mugilidae species were also seen up to 10 km from the sea. The eggs and larvae of anadromous fish were observed in the highest station. Kutum (Rutilus frisii) and Danube bleak (Alburnus chalcoides) fry fish had the highest abundance among the identified species of with 222 and 92 number/200m2, respectively. Bream (Vimba persa), Leaping mullet (Chelon saliens), European bitterling (Rhodeus amarus), Sanias spined loach (Cobitis saniae), North Caucasian bleak (Alburnus hohenackeri) had moderate frequency between 27 to 59 number/200m2 and the abundant of other species was low between 0.014 to19 number/200m2. The lowest Shannon's diversity index was in the furthest distance from the Caspian with value 1.03, while the highest value, with significantly difference p<0.05, was observed in 5 km to the sea with value 1.6  Also, the highest and lowest values ​​of the index were observed in November 2022 and January 2023, respectively.

About 30 species of commercial fish have been caught in the seawater of Guilan province annually and the most important species is Kutum (Rutilus frisii). The aim of this study was to determine the feeding indices, food spectrum, and dominant food items of fingerlings kutum under the investigation of feeding habits of kutum and grey mullets on the coasts of Guilan province. The fish were captured with a seine net with 6 mm mesh size from winter 2020 to autumn 2021 in the coastal areas of Talesh, Anzali, Kiashahr, and Chaboksar. The results on R. frisii with body weight 0.31-14.5 (3.64±2.8)g, total length 34.3-120 (68.3±19.0) mm and ages 0+ and 1+ years showed that the relative length of intestine is 0.59-1.16 (0.78±0.10). Vacuity index was calculated at 0, 0, 5, 0 and 1% in spring, summer, autumn, and winter seasons and the total of the year, respectively, and the mean fullness intensity was 372±267, 360±151, 230±173, 581±689 and 365±302 in spring until winter and total of the year, respectively, which showed significant differences (F=9.10, p<0.05). Detritus, filamentous algae, 26 genera of phytoplankton, 2 types of zooplankton and 13 types of benthic animals and as well as eggs and larvae of fish were observed in the gastrointestinal tract of kutum fingerlings with a frequency of presence 10, 73, 62, 5, 86 and 2 percent of all studied specimens, respectively. The phytoplanktonic genera of Cyclotella, Navicula and Nitzschia were observed in 60%, 52%, and 47% respectively, and gammaridae among the benthic animals had the most frequency in 68% of the fish. In general, according to the feeding indices, feed diversity, and dominance of feed items, kutum fingerlings are a benthic feeders and euryphagous with a good fullness intensity on Guilan coasts.

Silver carp, Hypophthalmichthys molitrix, is a plankton filter feeder fish and introduced to Chitgar Lake since 9 years ago. In this study, the effect of silver carp stocking was evaluated on the phytoplankton structure of Chitgar Lake at different seasons in 2018. Samples were caught with gill-net, beach seine and cast-net gears. The results obtained from 51 individuals with a total length of 111-473 (average total length of 325.8±134.6) mm showed that coefficient of vacuity, averages of relative gut length and feeding intensity were 0.00%, 5.91±1.65 and 628.4±274.7, respectively and therefore it showed over eating, herbivory and good feeding intensity in this fish. Silver carp fed on 32 phytoplankton and 11 zooplankton genera and phytoplankton and zooplankton were observed in 100% and 88% of studied specimens, respectively. Synedra, Navicula, Staurastrum and Cyclotella were the dominant phytoplankton genera (30.0, 22.2, 13.8 and 12.1%, respectively) and Bosmina and Alona were the dominant genera of zooplankton (84.0 and 7.2%, respectively). There were no seasonal changes in feeding intensity but there were seasonal changes in food items dominance. Releasing of 20000-30000 individuals of silver carp with a weight 50-100 g is suggested in order to protect water quality of Chitgar lake annually.

The study carried out in reproduction status project of commercial fishes of Anzali wetland from April 2016 until March 2017 and samples were caught using electroshocker in different points of studied area. The studied adult males (n=173) weight varied between 1.08 and 33.22 with an average of 7.12±4.06g and adult females (n=271) between 0.71 and 59.9 with an average of 12.66±9.16g. Total length were measured between 45.5 and 136 with an average of 80.02±14.03mm in adult males and between 41.3 and 166 with an average of 92.81±22.06mm in adult females, too. Age composition was from 2 to 11 and 1 to 15 years old for adult males(n=57) and females (n=130), respectively. Adult males and females formed 38.96% and 61.04% of adults. Monthly average of gonado-somatic index was determined 1% in August and 13.7% in April with an annual average of 6.54±7.08%for adult females. Spawning period of the fish species was determined on basis of gonado-somatic index and composition of gonad maturity stages of adult females from April to July. Absolute fecundity of studied fish (n=16) was calculated 3805-11483 with an average of 6898.1±1997.89 eggs and average of egg diameters was 0.9±0.1 mm. Although this fish has no economic value but this species is caught in Anzali wetland for consumption. Due to its Reproduction season, its overfishing should be avoided.

During 2006-2007, to estimate the length-weight and fork-total length relationships, growth pattern and condition factor of Alburnus chalcoides, a total of 170 specimens were collected from the Chelvand, Khalehsara, Siahdarvishan, Sefid, Pol, Tonekabon and Babol rivers. The length-weight relationship were estimated using W = aLb, length-length relationship by FL= a+ bTL and condition factor by K = (W/Lb) ×100 Formulae. The b-value was 2.5 to 3.25. Also, except Sefid and Babool rivers populations, others showed positive allometric growth pattern. Condition factor were calculated 0.72 to 0.96.

Due to the presence of taxonomic ambiguity regarding Petroleuciscus ulanus and Alburnus atropatenae and the tendency to treat them as synonyms of each other, this study was conducted to validate these two species by comparing their morphometric and meristic characters in the Mahabad-Chai River, Urmia Lake basin. A total of 64 specimens of P. ulanus and 68 specimens of A. atropatenae were sampled and were then investigated for 17 morphometric and 7 meristic characters. Measurements were standardized to eliminate the effects of size due to allometric growth pattern, then their normality and abnormality were examined. Standardized data were analyzed using t-test, Mann-Whitney, principal component analysis (PCA) and discriminative function analysis based on P-value of Hotelling's t-test (DFA/Hotelling's T-test) methods. The results showed that the two species were significantly different in 11 morphometric and 2 meristic traits (P<0.05). DFA analysis also showed significance differences between the two studied species. Our results refute the synonymy hypothesis of Petroleuciscus ulanus and Alburnus atropatenae on the basis of morphometric and meristic traits. Therefore, based on the results of this study, the taxonomic identities of these two species are valid.

This research was conducted in order to find the abilities of the downstream river of Ardabil Yamchi Dam and to determine suitable aquaculture places and to estimate the amount of production. For this purpose, available meteorological and climatic information of the region and data obtained from monthly and seasonal sampling in the field of physical and chemical factors of water, discharge and flood status, phytoplankton, zooplankton, benthic and fish communities, pollutants including heavy metals and agricultural pesticides and groundwater status were examined. The results of physical and chemical factors of water showed that almost all factors are in the right range of salmon farming. Bacillariophyta branch was predominant phytoplankton. According to benthos, biological index in stations 1 and 2 was very good to excellent. Also, 6 fish species from families of Cyprinidae and Nemacheilidae were identified in river. The amount of heavy metals examined was within the allowable standard range. Geophysical studies of groundwater showed that the thickness of the water layer is about 20 to 30 meters and acceptable to drinking according to Schuler diagram. The data showed that in general the Yamchi River can be exploited for cold-water aquatics, especially rainbow trout, and it is not possible to culture warm-water fish. Also, various rearing systems including race way and preferably a semi-recirculation system were proposed. In the current conditions of the river, if the minimum potentials of the region are used for aquaculture, production of at least 65 tons by race way up to a maximum of 650 tons in the semi-recirculation system and in case of allocating special water directly from Yamchi Dam Lake for aquaculture, a minimum of 300 to a maximum of3000 tons of salmon was predicted, respectively. In addition, it was recommended that aquaculture complexes be established instead of individuals.

During 2019, the length-weight, length-length relationships and condition factor of Caspian kutum, Rutilus kutum  (Kamensky, 1901) were studied by catching a total of 339 specimens were collected from Chelvand, Khalehsara, Sefid, Khoshk and Shir rivers, Anzali Wetland and Turkmen Shores of the Caspian Sea basin. The equation W =aTLb was used to calculate the length-weight relationship, FL=a + bTL for the length-weight relationship, and K= (W / L3) × 100 to calculate condition factor. The b-value were estimated from 2.47 to 3.17 and condition factor from 0.85 to 1.01. Maximum and minimum parameter of b-value and condition factor were related to the Khoshk River, Torkman shore and Anzali wetland and Sefid River, respectively. In addition, the growth pattern was positive allometric for the Chelvand, Khoshk and Shir populations, isometric for the Khalesara population and negative allometric for others.

Capoeta sevangi is a native species of the Cyprinidae family in the Caspian Sea basin (Arass River) and is ecologically and economically important. The main purpose of this study to investgate the relationship between absolute and relative fecundity with length, weight and age of this species in the Arass River and sampling was carried out from March to June 2012 using cast-net and gill-net. The result of the study on 72 female specimens of previous stages to prepare spawning showed that the absolute fecundity of this fish is 3056 to 21213 (10590.7±4085.0) eggs and the relative fecundity is 23.5 to 98.3 (41.1±11.9) eggs per gram of body weight and the egg diameter is 0.95 to 1.85 mm measured

Iranian goby is an endemic fish that was described in 2015 from rivers of the Guilan province. This fish exists upstream and mid-stream of rivers and it is observed lowly in downstream and rarely in estuaries of rivers. This study has been done in 4 important rivers of Anzali Wetland (Chafrud, Khalkaee, Siahdarvishan and Pasikhan) and the main purposes were determination of diet spectrum and food preference of the fish and samples was caught using electro-shocker from spring 2016 until winter 2017. Results on 54 individuals with a total length 47-137mm showed that coefficient of vacuity, averages of relative gut length and feeding intensity, 8.5%, 0.51±0.10 and 337.3±237.6, respectively. The studied fish fed on 26 food items belong to 21 animal families of worms (Oligochaeta), Bivalvia, insects consist of orders Coleoptera, Diptera, Ephemeroptera, Trichoptera, Crustacean (Isopoda and Palaemonidae) and bony fishes (Cyprinidae, Cobitidae and Gobiidae). Chironomidae, Baetidae and Simulidae were observed in 48.1, 14.8 and 11.1% of studied stomachs and they comprised about 74.3, 7.6 and 3.2% of total counted preys and were abundant. In general, the fish is a euryphagous and mainly benthivore fish and old individuals consume on nekton such as shrimps and fish species, too.

Anzali Wetland is one of the most important wetland in southern Caspian Sea where more than 45 endemic and native fish species were reported. In this study, distribution, abundance and IUCN category of fish species were investigated in Anzali Wetalnd during 2016-2017 according to research fishing and local fishermen data. The result showed that 45 fish species belong to 13 families exist in Anzali Wetland. The highest species diversity belongs to Cyprinidae and Gobiidae families with 25 and 6 species respectively.  There was distinguished 4 groups of fish consisting freshwater resident, Anadromous, estuarine and multi-habitat. Gambusia holbrooki, Carassius gibelio, Hemiculter leucisculus, Blicca bjoerkna and Rhodeus caspius were made 22. 8, 19. 7, 12. 1, 10. 1 and 8. 4% of total caught number, respectively. According to all data, the IUCN groups of Anzali Wetland fishes were categorized as 10 species in least concern, 10 species vulnerable, 5 species endangered and 6 species critically endangered. The protection of fish in Anzali wetland needs more attention and is necessary implementation of rehabilitation programs such as reducing the entry of various pollutants into the wetland, controlling invasive aquatic plants, sediment control, rehabilitating spawning sites and avoiding illegal fishing. Artificial propagation of endangered and critically endangered fish should be done for helping the fish for some years.

Indigenous and exotic fish species are of great importance in biological studies for a variety of reasons, including biodiversity, water indicators, and finally as a white in human food supply. A few fish fauna studies on Anzali lagoon have been done in previous years. The study of fish communities in Anzali wetland during 2013 to 2014 was done by sampling 14 stations by electroshock and cast-net in which 6757 fish specimens were caught, weighed and then 2763 of them were bioassay. Three species of non-native fish, prussian carp, Gambusia and sharp belly with 63.6%, had the highest frequency among the fish caught. Carassius gibelio was caught in all stations and in all seasons. The sex ratio (males: females) in C. gibelio was 1:11 and the age of the specimens was between 1 to 5 years. The average of total length and body weight was determined 126 mm and 46 g, respectively. The maximum total length was 315 mm with 621 g.

In the present study, the morphometric and meristic characteristics of 363 specimens of Rutilus kutum (Kamensky, 1901) collected from the Chelvand, Khalehsara, Sefid, Khoshk, Shir rivers and Anzali wetland, Chalous and Torkeman shores in the south Caspian Sea Basin were compared. All caught specimens were freshly transferred to the laboratory. In the Lab some 36 morphometric and nine meristic characters were measured and recorded. After standardization all data were analyzed using One-Way ANOVA, Duncan test, Canonical variate Analysis (CVA) and Cluster Analysis (CA). The results showed significant differences in 30 morphometric and two meristic traits between the studied populations (p < 0.05). The CVA was able to separate the studied populations and CA placed the Chalous populaion in a cluster separately from the others. Generally, the performance of the morphometric traits was superior to meristics in discrimination populations.Generally, the performance of the morphometric traits was superior to meristics in discrimination populations.

This study was conducted to study sexual dimorphism of Caspian kutum, Rutilus kutum collected from the Rudsar coast and Anzali Wetland, Guilan Province. After collecting, the left lateral face of the fresh specimens were photographed, then 13 Landmark-points were defined and digitized using tpsDig2 software. Generalized procrustes analysis was performed to eliminate non-shape effects, including size, direction and position. Then date was analyzed using principal component analysis (PCA) and discriminant function analysis (DFA) based on P-value obtained from Hoteling’s t-test. The results showed a significant difference in the body shape of the male and female (P<0.05). The observed differences confirm the presence of the sexual dimorphism in the study species during reproductive season. The observed morphological can be shown presence of the sexual dimorphism in this species. Based on the findings, the females have deeper body and smaller head, which can related to reproductive performance of each sex.

This study aimed to compare morphological variation of the two populations of the Eurasian perch (Perca fluviatilis L., 1758) from the Anzali wetland and Chamkhaleh River downstream by sampling 20 specimens from each in 2006. A total of 38 morphometric and 13 meristic characters were measured and counted. To eliminate the effects of allometric growth patterns the morphometric characteristics were standardized. The results showed a significant difference between studied populations in some morphometric and meristic traits (P<0.05). In the morphometric, eye diameter, head length, and predorsal and post dorsal-ventral lengths and in those of meristic the lateral line scales, numbers of the unbranched rays of 2ed dorsal-, anal- and ventral fins and upper gill rakers revealed significant differences between the Anzali and Chamkhaleh populations (P<0.05). The results showed that the two studied populations are separated by morphometric and meristic characters, therefore they should be considered as separate populations in future fisheries management plans.

The study of body length and weight, maturity age, sex ratio, egg diameter, fecundity and spawning season of common carp has been done and the main aim was help to its population rebuilding. 1023 specimens were caught in Anzali wetland monthly from October 2015 until March 2017. There was used sexual maturity stages 3-7 for determining adults and, Gonado-somatic index and sexual maturity stages for determining spapwning season. The results showed body weight 54.3-2264 (687.6±337.3) g in adult males (n=333) and 226.1-5483 (856.7±543.2) g in adult females (n=367) with significant difference between them (U=49999, P<0.01).Total length was measured 161-571 (369.3±63.1) mm in adult males and 260-761 (391.3±72.2) mm in adult females with significant difference between them (U=52040, P<0.01). Length maturity in 50% females was calculated 352 mm (TL). Adult males and females had 3-10 and 3-12 years old respectively, thus maturity in both sexes took place in 3 years old. Adult males number was 1.58 times than adult females in running ripe to newly fully spent individuals in spawning season (spring and summer) and it differed from standard value (X^2=10.8, P<0.01). There were 3 different batches of eggs (large, medium and small) in adult female ovaries, at least. The averages of absolute and relative batch fecundity (only large eggs) were estimated 170977.6±176651.3 eggs and 132400±62400 eggs per one kilogram of female body weight, respectively. Common carps spawned from late March until October in Anzali wetland in a water temperature of 13-27 °c. This study showed common carp individuals select only multiple batch spawning model per a spawning period, which according with more spawning months and fecundity than other southern Caspian Sea basin.

Acanthobrama urmianus is an endemic species of Cyprinidae family in the Urmia Lake basin and important for ecological and sport fishing. The main purpose of this study was to investigate the relationship between the fecundity with length, weight and age in two rivers of Mahabadchai and Siminerud and sampling was carried out from December to June using cast-net and gill-net. The result of the study on 107 female fish specimens from maturity stages 4 and 5 showed that the absolute fecundity of this fish is 1567 to 27228 (11954.3±6991.9) eggs with a diameter of 0.35 to 1.42 and the relative fecundity is 87.9 to 633.9 with an average of 282.6±120.7. Also, with increasing age and size of the fish body, the absolute fecundity increased. Between the absolute fecundity and the total length of equation F= .0034TL 3.545 (r2=.789) and between the absolute fecundity and the weight of the equation F=23.272W1.665 (r2=.766) obtained. The results showed that the rate of fecundity in Mahabadchai in the constant length range was less than Siminerud River.

Lake of the Persian Gulf Martyrs has been constructed in the northwest of Tehran in 22 urban areas, which in addition to creating a recreational-tourism environment, has caused an increasing economic value to the adjacent lands. The declining water quality of the lake and the increasing abundance of rough and invader fishes such as Prussian carp (Carassius gibelio) and Sharpbelly (Hemiculter leucisculus) are a threat for ecosystem of the lake. In order to control these fishes, pike (Esox Lucius) as a predator was released in the lake. After introduction of pike was studied its diet and growth, and the changes of invasive fish population in 2018-2019. Lincoln–Petersen method showed that the population of Prussian carp was decreased from 20,000 to 8,300 individuals in lake. CPUE showed that population of Sharpbelly has been reduced from 712,000 to about 3,000 individuals in the lake. Using Jolly-Seber method, population of Sharpbelly from the lake shore did not change much during the study period. The population of Pike was estimated at 575 that with continuous feeding of invader fishes had a weight gain of 3.7±6.1 grams per day. The occurrence percentage of Prussian carp was more than other preys; Sharpbelly and topmouth gudgeon (Pseudorasbora parva). Due to the increase in the size of the Pike, the small fish in the lake do not have much nutritional benefit for the pike and in the current situation, only the Prussian carp fish are fed. In order to better control of the invader fish, the use of small-sized predatory fish seems necessary.

Morphological variations (morphometric and meristic traits), length-weight relationship parameters and condition factor were studied in autumn and spring populations of Alburnus chalcoides, collected from Sefid River (45 autumn and 113 spring) and Siahdarvishan (22 autumn and 28 spring) in the southern Caspian Sea basin. After anesthesia and fixation into the 4% buffered formalin, the samples were transferred to the laboratory and a total of 22 morphometric and 8 meristic characters were measured and counted using caliper and stereo-microscope, respectively. The results showed that the autumn and spring migratory populations of the studied species in the Sefid and Siahdarvishan rivers have significant differences in 7 and 2 morphometric traits (P<0.05), respectively, but not different in meristic characters (P>0.05). The results of the length-weight relationship parameters revealed that the Sefid River populations has an isometric growth pattern and the autumn and spring populations of the Siahdarvishan River showed positive allometric and isometric growth patterns, respectively.

Tench an economically important species in Anzali Lagoon has experienced a sharp catch decline in recent years. The present study aims at examining certain biological traits of the fish in Anzali lagoon. A sample of 96 pieces of such fish were netted out through gillnet fishing during Jan 2006-July 2007.  The findings showed incongruity in 11 out of 36 morphometric traits followed by 1 out of 10 numerical traits among male and female fish (p ≤0.05). Body weight of the fish varied from 40.7 up to 299.3gr with the mean figures for male and female fish at 117.8±51.0 and 117.8±54.4gr respectively. Fork length ranged from 135.2 to 255.7 with the mean 182.o±27.7 and 181.9±23.6mm for male and female fish respectively, showing no difference between them .The male fish age ranged from 2 to 7 years and for the female ones, it was 2-6.yrs with the 3-4 years as the dominant age group in both sexes. The male constituted 46.9 % of the fish population followed by 53.1% of female ones showing no major difference with the standard (1:1) ratio(x 2=0.38). In addition, the gradient of the b regression line between the body weight and fork length of male and female fish were found to be 3.21 and 2.99 respectively with isometric growth in both sexes. The average condition factor in male fish was 1.82±0.23 and 1.86±0.24 in female with the recorded relative condition factor were 0.99±0.13 in male fish and 1.01±13 in female ones revealing no differences across sexes. Absolute fecundity of 24 sample fish varied between 14000 and 154000 with relative fecundity falling between 170.1 to 644.8 pieces of egg per each gram of female fish.

In this study the morphometric and meristic characteristics of 98 specimens of Garra rufa collected from the Gamasiab, Aran, and Dinvar Rivers (Karkheh River drainage) and Bazoft and Armand rivers (Karun River drainage). The samples were transferred to the Lab after anesthesia and fixed into the buffered formalin 10%. Thirty-three morphometric and 9 meristic traits were measured and counted using digital caliber and stereomicroscope, respectively. Morphometric data were standardized based on the ratio of the head and standard lengths. To compare the studied populations, in terms of the morphological features, One-Way ANOVA, Duncan test, PCA (Principal Component Analysis), CVA (Canonical Variate Analysis) and CA (Cluster Analysis) were used. The results showed a significant difference among the studied populations in all morphometric data except post dorsal- pre Anal and Post-orbital lengths and in lateral and lower line scales, upper and lower gill rackers (p < 0.05). CVA and CA analysis showed population grouping as well. The morphometric was better than those counting traits in expressing the differences among the studied populations.