For this research, 240 pieces of sea carp fry (with an average weight of 5±1g) were transported in 4 different salinity treatments of 0, 1, 3 and 6 g/l in three replicates (in plastic bags) for one hour. In order to check the blood parameters of the baby fish at the end of the experiment, blood was taken from the samples by cutting the tail stem. According to the results of measuring some biochemical parameters of blood serum, the amount of total protein did not show a significant difference between different treatments (P>0.05), but the amount of glucose and cortisol showed a significant decrease in saline treatments compared to the control (P<0.05). The results of measuring liver enzymes in the amount of alanine aminotransferase, aspartate aminotransferase and alkaline phosphatase showed no significant difference between different treatments (P>0.05). The results of measuring some blood hematology factors also indicated no significant difference in the number of red and white blood cells, hematocrit percentage and hemoglobin level in the treatments. (P>0.05). In general, it can be said that Fewer stress indicators were observed in the transported fish treated with 3 grams of salt per liter.

In order to asses the immunogenicity of Aeromonas hydrophila, the aethiological cause of haemmorhagic septicemia in common carp in Fars province fish farms, three different preparations of antigen including formalin-killed cell (1%) heat killed cell (60oC, 4h) and live cell were studied. Fifty five common carp (Cyprinus carpio, L) in 9 groups with three routes of administration were exposed to the antigens (oral administration 109 cell/ml/fish, immersion 107 cell/ml/fish and ip injection 109 cell\fish) in day 0 and day 20 of the experiment Similarly 15 fish in three groups were exposed with phosphate - buffered saline as control. Fish were bled 45 and 60 days after immunization and serum sample from each fish was collected. The fish humeral response was detected by ELISA.Results showed that the formalin-killed cell had the best response and that oral administration of antigens in comparison with other routes had the highest effect. The antibody level of fish was still increasing at day 60.

Introduction: The "Tata" is a type of common carp bred in Hungary, whose eyed eggs are introduced to Iran a few years ago to address the challenges faced by warm water fish farmers due to a lack of access to quality broodstock and modified fry with rapid growth rates. This study aims to evaluate the advantages of the Tata strain compared to the farmed common carp in Guilan Province by comparing the propagation indices and growth performance of their juveniles Materials and Methods: Both breeds were propagated through a single injection of the Ovulin hormone. Following a 60-day rearing period, fish with an average initial weight of 21 gr were kept in fiberglass tanks. Results and Discussion: percentage, measuring 1.53 ± 0.05 mm and 97.50 ± 0.76%, respectively (p<0.05). Additionally, the average hatch percentage for the Tata breed was 98.00 ± 0.58%, which is 13% higher than that of the farmed breed. The average weight of one-day-old Tata larvae was 2.54 ± 0.03 mg, significantly greater than the average weight of one-day-old larvae of the farmed breed, which was 1.68 ± 0.04 mg (p<0.05). There were no significant differences in sperm motility and lifespan between the two breeds, although the spermatocrit of the Tata breed was notably lower than that of the farmed breed. In terms of growth performance, the study found that, under equal rearing conditions, the Tata breed demonstrated significantly higher average final weight and total length, percentage of Weight Gain and Length Gain, specific growth factor, average daily growth, and feed efficiency, while exhibiting a lower food conversion factor compared to the farmed breed (p<0.05). Conclusion: The most significant advantages of the Tata breed identified in this study include higher quality eggs, a greater percentage of embryo survival and hatching rates, and superior growth performance compared to the farmed breed. Therefore, the Tata breed could be a suitable candidate for selection and breeding in future genetic improvement programs.

One of the most important breeding-related issues of common carp is artificial reproduction and studying the fecundity status as a quantitative index in reproduction. For this reason, we investigated the effect of female age of common carp on reproductive and morphological indices including weight, length, condition factor, eggs weight, fecundity, number of eggs per gram, and relative fecundity per weight and length. For this purpose, two groups of females (2 and 3 years old) were compared. The 3-year-old fish showed higher average weight (4536.7±713.0 g), total length (64.9±3.1 cm), obtained eggs (664.3±69.9 g), working fecundity (600847.3±91984.4 eggs), and relative fecundity per length (74748.8 ±2194.2 eggs) than the 2-year-old fish (P<0.05). Also, condition factor (1.8±0.2), number of eggs per gram (1000.7±137.8), and relative fecundity per weight (1646943.3±51362.9 eggs) in the 2-year-old fish were higher than those in the 3-year-old fish (P<0.05). The comparison of two age groups of fish showed that there is a significant difference in all measured parameters. Increase in age, weight and length of common carp broodstocks had positive effect on fecundity, weight and size of obtained eggs, and older, heavier and larger fish showed less number of eggs per gram, while the eggs were in larger size. According to the results, common carp females with higher age, weight, and size are more appropriate for artificial reproduction.

Ten common carp fish weighing 500-600 g and 28-30 cm in length, comprising both sexes, were collected from fish culture ponds, around Ardebil city. Dewaxed sections (5-6 μm) were stained for histological and histochemical purposes with haematoxylin and eosin (H&E), periodic-acid Schiff (PAS) and Alcian blue. The histological and histochemical characteristics of the esophagus and intestine were studied by the use of a light microscope. The gastrointestinal tract of the common carp was divided into an esophagus and intestine. The esophagus was short, with longitudinal mucosal folds but The intestine have shorter mucosal folds in than the esophagus folds and a thinner wall in comparison with esophagus. The histological structure was divided in four layers: mucosa, submucosa, muscular, and serosa. Intestinal mucosa displayed many simple columnar epithelium in associated with goblet cells and intraepithelial lymphocytes. Histochemical analysis showed that the goblet cells have acidic and neutral mucosubstances.