University of Guilan Aquatic Animals Nutrition 2980-8499 11 3 2026 08 09 Evaluation of the trypsin activity extracted from the pyloric caeca and intestine of Siberian sturgeon (Acipenser baerii) under some physical and chemical factors Evaluation of the trypsin activity extracted from the pyloric caeca and intestine of Siberian sturgeon (Acipenser baerii) under some physical and chemical factors 1 15 9757 10.22124/janb.2025.31285.1296 FA Abbas Zamani Department of Fisheries, Faculty of Natural Resources and Environment, Malayer University, Malayer, Hamadan, Iran Journal Article 2025 05 19 Introduction: The ability of fish to digest food particles depends on the presence of digestive enzymes in the gastrointestinal tract. In gastric fish species, proteolytic enzymes especially pepsin, trypsin, and chymotrypsin appear to play a very important role in catalyzing hydrolysis process of certain peptide bonds. Trypsin, as a serineprotease, complete the acid predigestion of protein delivered to the stomach in combination with other alkaline proteases and peptidases where specifically cleaves at the carboxylic side of lysine and arginine residues. Therefore, trypsin activity could be a sensitive and reliable indicator of nutritional and physiological status of fish at different stages of growth. The aim of this work was to study the effect of some physicochemical factors on the activity of extracted trypsin from pyloric caeca and intestine of Siberian sturgeon (Acipenser baerii). Materials and Methods: The collected fish viscera from 10 samples (5 ± 0.4 kg) were transported to the laboratory and after separating the pyloric caeca and intestine, those samples were washed with cold distilled water (4 °C), pooled and then homogenized in 50 mM Tris-HCl buffer. After centrifugation at 4 °C, the resulting supernatant from each sample was collected and finally, the physicochemical factors including optimum temperature, thermostability, optimum pH, pH stability, inhibitors and metal ions were evaluated on the extracted trypsin according to the standard protocols. Data obtained from the experimental assessments was analyses by a One-Way ANOVA and the comparison of means was carried out by Duncan’s multiple range tests with a statistical significance at P<0.05. Results and Discussion: According to the results, optimum temperature of the trypsin from pyloric caeca and intestine was recorded at 55 °C. Similar optimum temperature was recorded for trypsins in silver mojarra, unicorn leatherjacket, beluga and sevruga. The optimal temperature of trypsin is in the range of 30-60 °C and the differences could be attributed to the temperature of fish habitat or experimental conditions used in assessments. The stability of the trypsin was well preserved at temperatures of up to 50 °C. The results of thermostability were in accordance with those of mandarin fish, mrigal carp, common dolphin fish, beluga and sevruga. In general, thermostability of the trypsin enzyme might vary by some factors such as fish species and experimental conditions. The optimum pH of trypsin from both samples was recorded at 8.0 and the results were similar to data reported from trypsin in other species such as mrigal carp and common dolphinfish. The pH stability of trypsin from both samples was highly preserved at pH values comprised between 7.0 and 11.0. Similar results were reported for trypsins from grey triggerfish, zebra blenny, catfish, common dolphin fish, beluga and sevruga. The high ranges of pH may change the net charge and conformation of an enzyme and inhibit to bind to substrate properly, resulting in the abrupt loss of enzymatic activity. Trypsins are mainly known to be more activity within a range of pH values comprised between 7.5 and 10.5. The inhibitors SBTI, TLCK, PMSF, TPCK, pepstatin A, iodoacetic acid, and EDTA significantly inhibited the enzyme activity, whereas SBTI and TLCK had a completely inhibitory effect on the enzymatic activity (P<0.05). The sensitivity of protease enzymes to various inhibitors is a valuable tool for their proper functional characterization. Our findings were in agreement with data reported in the brownstripe red snapper, silver mojarra, zebra blenny, mrigral carp, Asian seabass, beluga and sevruga. The enzyme activity was significantly increased in the presence of Ca+2 and Mg+2 and decreased by Cu+2, Ba+2, Zn+2, and Al+3 (P<0.05). Our results were in agreement with data reported in mandarin fish, zebra blenny, common dolphin fish, beluga and sevruga. Metal ions can affect enzyme-catalyzed reactions by changing the electron flow in a substrate or enzyme and play a key role in binding to the substrate, depending on the functional groups present in the active site of enzyme. Conclusion: Based on the obtained results, the extracted trypsin activity from Siberian sturgeon pyloric caeca and intestine was significantly affected by the evaluated physicochemical factors that can be effective on the optimal activity of the enzyme in the digestive physiology of the fish. Introduction: The ability of fish to digest food particles depends on the presence of digestive enzymes in the gastrointestinal tract. In gastric fish species, proteolytic enzymes especially pepsin, trypsin, and chymotrypsin appear to play a very important role in catalyzing hydrolysis process of certain peptide bonds. Trypsin, as a serineprotease, complete the acid predigestion of protein delivered to the stomach in combination with other alkaline proteases and peptidases where specifically cleaves at the carboxylic side of lysine and arginine residues. Therefore, trypsin activity could be a sensitive and reliable indicator of nutritional and physiological status of fish at different stages of growth. The aim of this work was to study the effect of some physicochemical factors on the activity of extracted trypsin from pyloric caeca and intestine of Siberian sturgeon (Acipenser baerii). Materials and Methods: The collected fish viscera from 10 samples (5 ± 0.4 kg) were transported to the laboratory and after separating the pyloric caeca and intestine, those samples were washed with cold distilled water (4 °C), pooled and then homogenized in 50 mM Tris-HCl buffer. After centrifugation at 4 °C, the resulting supernatant from each sample was collected and finally, the physicochemical factors including optimum temperature, thermostability, optimum pH, pH stability, inhibitors and metal ions were evaluated on the extracted trypsin according to the standard protocols. Data obtained from the experimental assessments was analyses by a One-Way ANOVA and the comparison of means was carried out by Duncan’s multiple range tests with a statistical significance at P<0.05. Results and Discussion: According to the results, optimum temperature of the trypsin from pyloric caeca and intestine was recorded at 55 °C. Similar optimum temperature was recorded for trypsins in silver mojarra, unicorn leatherjacket, beluga and sevruga. The optimal temperature of trypsin is in the range of 30-60 °C and the differences could be attributed to the temperature of fish habitat or experimental conditions used in assessments. The stability of the trypsin was well preserved at temperatures of up to 50 °C. The results of thermostability were in accordance with those of mandarin fish, mrigal carp, common dolphin fish, beluga and sevruga. In general, thermostability of the trypsin enzyme might vary by some factors such as fish species and experimental conditions. The optimum pH of trypsin from both samples was recorded at 8.0 and the results were similar to data reported from trypsin in other species such as mrigal carp and common dolphinfish. The pH stability of trypsin from both samples was highly preserved at pH values comprised between 7.0 and 11.0. Similar results were reported for trypsins from grey triggerfish, zebra blenny, catfish, common dolphin fish, beluga and sevruga. The high ranges of pH may change the net charge and conformation of an enzyme and inhibit to bind to substrate properly, resulting in the abrupt loss of enzymatic activity. Trypsins are mainly known to be more activity within a range of pH values comprised between 7.5 and 10.5. The inhibitors SBTI, TLCK, PMSF, TPCK, pepstatin A, iodoacetic acid, and EDTA significantly inhibited the enzyme activity, whereas SBTI and TLCK had a completely inhibitory effect on the enzymatic activity (P<0.05). The sensitivity of protease enzymes to various inhibitors is a valuable tool for their proper functional characterization. Our findings were in agreement with data reported in the brownstripe red snapper, silver mojarra, zebra blenny, mrigral carp, Asian seabass, beluga and sevruga. The enzyme activity was significantly increased in the presence of Ca+2 and Mg+2 and decreased by Cu+2, Ba+2, Zn+2, and Al+3 (P<0.05). Our results were in agreement with data reported in mandarin fish, zebra blenny, common dolphin fish, beluga and sevruga. Metal ions can affect enzyme-catalyzed reactions by changing the electron flow in a substrate or enzyme and play a key role in binding to the substrate, depending on the functional groups present in the active site of enzyme. Conclusion: Based on the obtained results, the extracted trypsin activity from Siberian sturgeon pyloric caeca and intestine was significantly affected by the evaluated physicochemical factors that can be effective on the optimal activity of the enzyme in the digestive physiology of the fish.

https://janb.guilan.ac.ir/article_9757_239c17945e65be7bb75ecc0d4550de3c.pdf

University of Guilan Aquatic Animals Nutrition 2980-8499 11 3 2026 08 11 Assessment of antioxidant activity in microalgae and macroalgae using various analytical assays and extraction solvents Assessment of antioxidant activity in microalgae and macroalgae using various analytical assays and extraction solvents 17 30 9755 10.22124/janb.2026.33027.1303 FA Hasti Beigzadeh Department of Natural Resources, Isfahan University of Technology, Isfahan, Iran, 8415683111 Omidvar Farhadian Department of Natural Resources, Isfahan University of Technology, Isfahan, Iran, 8415683111 Eisa Ebrahimi Dorcheh Department of Natural Resources, Isfahan University of Technology, Isfahan, Iran, 8415683111 Farideh Balali Department of Natural Resources, Isfahan University of Technology, Isfahan, Iran, 8415683111 Journal Article 2025 05 21 Introduction: Algae are rich in bioactive compounds and can grow in harsh environments, producing secondary metabolites with high biological value. They are considered natural sources of antioxidants, offering safer alternatives to synthetic compounds like Butylated hydroxyanisole (BHA) and Butylated hydroxytoluene (BHT). Brown algae generally exhibit higher antioxidant activity than green or red algae. Green algae, such as the genus Ulva, are rich in proteins, minerals, fatty acids, and antimicrobial compounds. Materials and Methods: Microalgae (Tetraselmis tetrathele and Scenedesmus quadricauda) and macroalgae (Sargassum ilicifolium and Ulva lactuca) were collected, cleaned, dried, and powdered. Ethanolic and acetone extracts were prepared using maceration. Antioxidant activity was evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH), Ferric Reducing Ability of Plasma (FRAP), and 3-ethylbenzothiazoline-6-sulfonate)2/2- azinobis (ABTS) assays. All experiments were performed in triplicate, and data were analyzed using t-tests in SPSS. Results: Antioxidant activity varied significantly with algae species, solvent, and assay type. For macroalgae, S. ilicifolium showed higher antioxidant activity than U. lactuca, with acetone extracts more effective in DPPH, while ethanol extracts were stronger in ABTS. For microalgae, ethanol extracts of T. tetrathele and S. quadricauda showed higher DPPH and FRAP activity, while ABTS results showed high antioxidant capacity for both solvents. Solvent type influenced the extraction of different antioxidant compounds. Discussion: The results confirm that antioxidant capacity depends on species, extraction solvent, and assay method. Brown algae like S. ilicifolium contain diverse phlorotannins, enhancing free radical scavenging. Microalgae contain polar compounds like carotenoids and chlorophylls, which are better extracted with ethanol. Differences among assays reflect distinct mechanisms of antioxidant action. Conclusion: All algae studied are valuable natural sources of antioxidants. S. ilicifolium and T. tetrathele are particularly potent, highlighting the importance of species selection and extraction methods. Algae can be sustainably used in food, pharmaceutical, cosmetic, and biotechnological applications. Introduction: Algae are rich in bioactive compounds and can grow in harsh environments, producing secondary metabolites with high biological value. They are considered natural sources of antioxidants, offering safer alternatives to synthetic compounds like Butylated hydroxyanisole (BHA) and Butylated hydroxytoluene (BHT). Brown algae generally exhibit higher antioxidant activity than green or red algae. Green algae, such as the genus Ulva, are rich in proteins, minerals, fatty acids, and antimicrobial compounds. Materials and Methods: Microalgae (Tetraselmis tetrathele and Scenedesmus quadricauda) and macroalgae (Sargassum ilicifolium and Ulva lactuca) were collected, cleaned, dried, and powdered. Ethanolic and acetone extracts were prepared using maceration. Antioxidant activity was evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH), Ferric Reducing Ability of Plasma (FRAP), and 3-ethylbenzothiazoline-6-sulfonate)2/2- azinobis (ABTS) assays. All experiments were performed in triplicate, and data were analyzed using t-tests in SPSS. Results: Antioxidant activity varied significantly with algae species, solvent, and assay type. For macroalgae, S. ilicifolium showed higher antioxidant activity than U. lactuca, with acetone extracts more effective in DPPH, while ethanol extracts were stronger in ABTS. For microalgae, ethanol extracts of T. tetrathele and S. quadricauda showed higher DPPH and FRAP activity, while ABTS results showed high antioxidant capacity for both solvents. Solvent type influenced the extraction of different antioxidant compounds. Discussion: The results confirm that antioxidant capacity depends on species, extraction solvent, and assay method. Brown algae like S. ilicifolium contain diverse phlorotannins, enhancing free radical scavenging. Microalgae contain polar compounds like carotenoids and chlorophylls, which are better extracted with ethanol. Differences among assays reflect distinct mechanisms of antioxidant action. Conclusion: All algae studied are valuable natural sources of antioxidants. S. ilicifolium and T. tetrathele are particularly potent, highlighting the importance of species selection and extraction methods. Algae can be sustainably used in food, pharmaceutical, cosmetic, and biotechnological applications.

https://janb.guilan.ac.ir/article_9755_3b615bdf0e105ec4128c535135d15b60.pdf

University of Guilan Aquatic Animals Nutrition 2980-8499 11 3 2026 08 11 Effects of lysophospholipid in diet containing astaxanthin on immune indices, antioxidant enzymes, and carotenoid content in koi carp (Cyprinus carpio var. koi) Effects of lysophospholipid in diet containing astaxanthin on immune indices, antioxidant enzymes, and carotenoid content in koi carp (Cyprinus carpio var. koi) 31 43 9754 10.22124/janb.2026.33458.1306 FA Arian Chalaki Department of Fisheries, Faculty of Animal Science and Fisheries, Sari Agricultural Sciences and Natural Resources University, Sari, Mazandaran, Iran Sakineh Yeganeh Department of Fisheries, Faculty of Animal Science and Fisheries, Sari Agricultural Sciences and Natural Resources University, Sari, Mazandaran, Iran Batoul Adhami Department of Fisheries, Faculty of Animal Science and Fisheries, Sari Agricultural Sciences and Natural Resources University, Sari, Mazandaran, Iran Journal Article 2025 07 16 Introduction: Ornamental fish are aquatic animals primarily reared in aquariums and decorative ponds for aesthetic purposes rather than human consumption. Among freshwater ornamental species, koi carp (Cyprinus carpio var. koi) is one of the most popular due to its remarkable diversity of colors and patterns, which significantly determine its market value. Therefore, understanding pigments and their dietary sources is essential in ornamental aquaculture. Carotenoids are the main compounds responsible for coloration in ornamental fish, however, fish species such as koi cannot synthesize them independently and must obtain them through feed. Astaxanthin, an important carotenoid with strong antioxidant properties, supports health, immunity, and skin coloration. Lysophospholipids may enhance fat-soluble compound absorption, improving astaxanthin uptake. This study evaluated their effects on pigment absorption, immunity, and antioxidant indices in koi carp. Materials and Methods: A total of 150 koi carp (with an initial mean weight 3.63 ± 0.05 g) were purchased from a local farm and transferred to a private rearing facility. After a two-week acclimation period on a commercial ornamental fish diet, the fish were randomly distributed into 15 glass aquaria (60 L; 60 × 45 × 20 cm) with 5 treatments, 3 replicates, and 10 fish per aquarium. Water quality was maintained by filtration, at temperature 26 ± 1°C, pH 7.5 ± 0.5, and dissolved oxygen 7 ± 0.5 mg/L. Synthetic astaxanthin (>98% purity) and lecithin-based lysophospholipid were added to the basal diet by spraying with canola oil. Treatments included: control, 0.01% astaxanthin, 0.02% astaxanthin, 0.01% astaxanthin + 0.1% lysophospholipid, and 0.02% astaxanthin + 0.1% lysophospholipid. Fish were fed at 5% body weight, three times daily, for 56 days. At the end of the feeding trial, serum lysozyme, alternative complement activity (ACH50), immunoglobulin, and antioxidant enzymes including superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) were measured using standard spectrophotometric methods. Serum, skin, and fillet carotenoids were also assessed. Data were analyzed using One-Way ANOVA followed by Duncan’s test in SPSS version 19, with significance set at P<0.05. Results: According to the immune parameters, lysozyme activity was significantly lower in the control and diet containing 0.01% astaxanthin compared to other groups (P<0.05). Immunoglobulin and complement activities were also significantly influenced by the different diets, with the combined astaxanthin–lysophospholipid groups showing the highest values (P<0.05). The highest CAT activity was recorded in fish fed the diet containing 0.01% astaxanthin supplemented with 0.1% lysophospholipid (P<0.05). The lowest SOD activity was observed in the control and 0.01% astaxanthin groups, while the addition of lysophospholipid to diets containing astaxanthin significantly increased SOD activity (P<0.05). Likewise, fish receiving the combination of lysophospholipid and astaxanthin, as well as the diet containing 0.02% astaxanthin, showed higher GPx activity than the control group (P<0.05). Carotenoid accumulation in the skin and fillet was significantly higher in fish fed astaxanthin-supplemented diets, particularly when combined to lysophospholipid (P<0.05). Discussion: Assessment of immune parameters in fish is an important indicator of health and immune efficiency, since these markers reflect both innate and acquired defense capacity. In the present study, adding astaxanthin to lysophospholipid synergistically improved lysozyme, complement, and immunoglobulin activities. This effect was probably due to better astaxanthin absorption caused by lysophospholipid, which enhances bioavailability through mixed micelle formation and facilitation of lipid transport. Antioxidant enzymes such as SOD, CAT, and GPx play crucial roles in mitigating oxidative stress and maintaining fish health. Here, astaxanthin-containing diets increased antioxidant enzyme activities compared to the control, and the best antioxidant performance was observed with combination of 0.01% astaxanthin and 0.1% lysophospholipid. This suggests a synergistic effect between the two additives. Similar improvements in antioxidant capacity have been reported in trout, tilapia, shrimp, and other aquatic species. Astaxanthin also increased carotenoid deposition in koi skin and fillet, improving pigmentation and likely market value. The inclusion of lysophospholipid further enhanced carotenoid accumulation in tissues, probably by improving emulsification and intestinal uptake of this fat-soluble pigment. In contrast, lower serum carotenoid levels in combined treatments may indicate faster transfer from blood to target tissues. Conclusion: Based on the present research, it can be stated that the combination of lysophospholipid and astaxanthin, particularly at the 0.01% level, likely enhanced tissue deposition of astaxanthin, which may reflect improved bioavailability, and concurrently improved antioxidant capacity and immune function. Introduction: Ornamental fish are aquatic animals primarily reared in aquariums and decorative ponds for aesthetic purposes rather than human consumption. Among freshwater ornamental species, koi carp (Cyprinus carpio var. koi) is one of the most popular due to its remarkable diversity of colors and patterns, which significantly determine its market value. Therefore, understanding pigments and their dietary sources is essential in ornamental aquaculture. Carotenoids are the main compounds responsible for coloration in ornamental fish, however, fish species such as koi cannot synthesize them independently and must obtain them through feed. Astaxanthin, an important carotenoid with strong antioxidant properties, supports health, immunity, and skin coloration. Lysophospholipids may enhance fat-soluble compound absorption, improving astaxanthin uptake. This study evaluated their effects on pigment absorption, immunity, and antioxidant indices in koi carp. Materials and Methods: A total of 150 koi carp (with an initial mean weight 3.63 ± 0.05 g) were purchased from a local farm and transferred to a private rearing facility. After a two-week acclimation period on a commercial ornamental fish diet, the fish were randomly distributed into 15 glass aquaria (60 L; 60 × 45 × 20 cm) with 5 treatments, 3 replicates, and 10 fish per aquarium. Water quality was maintained by filtration, at temperature 26 ± 1°C, pH 7.5 ± 0.5, and dissolved oxygen 7 ± 0.5 mg/L. Synthetic astaxanthin (>98% purity) and lecithin-based lysophospholipid were added to the basal diet by spraying with canola oil. Treatments included: control, 0.01% astaxanthin, 0.02% astaxanthin, 0.01% astaxanthin + 0.1% lysophospholipid, and 0.02% astaxanthin + 0.1% lysophospholipid. Fish were fed at 5% body weight, three times daily, for 56 days. At the end of the feeding trial, serum lysozyme, alternative complement activity (ACH50), immunoglobulin, and antioxidant enzymes including superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) were measured using standard spectrophotometric methods. Serum, skin, and fillet carotenoids were also assessed. Data were analyzed using One-Way ANOVA followed by Duncan’s test in SPSS version 19, with significance set at P<0.05. Results: According to the immune parameters, lysozyme activity was significantly lower in the control and diet containing 0.01% astaxanthin compared to other groups (P<0.05). Immunoglobulin and complement activities were also significantly influenced by the different diets, with the combined astaxanthin–lysophospholipid groups showing the highest values (P<0.05). The highest CAT activity was recorded in fish fed the diet containing 0.01% astaxanthin supplemented with 0.1% lysophospholipid (P<0.05). The lowest SOD activity was observed in the control and 0.01% astaxanthin groups, while the addition of lysophospholipid to diets containing astaxanthin significantly increased SOD activity (P<0.05). Likewise, fish receiving the combination of lysophospholipid and astaxanthin, as well as the diet containing 0.02% astaxanthin, showed higher GPx activity than the control group (P<0.05). Carotenoid accumulation in the skin and fillet was significantly higher in fish fed astaxanthin-supplemented diets, particularly when combined to lysophospholipid (P<0.05). Discussion: Assessment of immune parameters in fish is an important indicator of health and immune efficiency, since these markers reflect both innate and acquired defense capacity. In the present study, adding astaxanthin to lysophospholipid synergistically improved lysozyme, complement, and immunoglobulin activities. This effect was probably due to better astaxanthin absorption caused by lysophospholipid, which enhances bioavailability through mixed micelle formation and facilitation of lipid transport. Antioxidant enzymes such as SOD, CAT, and GPx play crucial roles in mitigating oxidative stress and maintaining fish health. Here, astaxanthin-containing diets increased antioxidant enzyme activities compared to the control, and the best antioxidant performance was observed with combination of 0.01% astaxanthin and 0.1% lysophospholipid. This suggests a synergistic effect between the two additives. Similar improvements in antioxidant capacity have been reported in trout, tilapia, shrimp, and other aquatic species. Astaxanthin also increased carotenoid deposition in koi skin and fillet, improving pigmentation and likely market value. The inclusion of lysophospholipid further enhanced carotenoid accumulation in tissues, probably by improving emulsification and intestinal uptake of this fat-soluble pigment. In contrast, lower serum carotenoid levels in combined treatments may indicate faster transfer from blood to target tissues. Conclusion: Based on the present research, it can be stated that the combination of lysophospholipid and astaxanthin, particularly at the 0.01% level, likely enhanced tissue deposition of astaxanthin, which may reflect improved bioavailability, and concurrently improved antioxidant capacity and immune function.

https://janb.guilan.ac.ir/article_9754_b1746c74eea183cefd7ed6d0b8bdf0fe.pdf

University of Guilan Aquatic Animals Nutrition 2980-8499 11 3 2025 09 23 Length-weight relationship and condition factor of longnose trevally (Platycaranx chrysophrys) of the coast of Qeshm Island, Iran Length-weight relationship and condition factor of longnose trevally (Platycaranx chrysophrys) of the coast of Qeshm Island, Iran 45 61 9811 10.22124/janb.2026.33357.1304 FA Jalil Sadeghi Jirofti Persian Gulf and Oman Sea Ecological Research Center, Iranian Fisheries Science Research Institute, Agricultural Research Education and Extension Organization, Bandar Abbas, Iran Hamed Shabanloo Persian Gulf and Oman Sea Ecological Research Center, Iranian Fisheries Science Research Institute, Agricultural Research Education and Extension Organization, Bandar Abbas, Iran Fereshte Seraji Persian Gulf and Oman Sea Ecological Research Center, Iranian Fisheries Science Research Institute, Agricultural Research Education and Extension Organization, Bandar Abbas, Iran Journal Article 2025 07 23 Introduction: Reports from the Iranian Fisheries Research Organization (IFRO) suggest that fish stocks in the Persian Gulf are largely fully exploited or overexploited. Over the past decade, fishing effort in the region has increased, while management measures have focused mainly on limiting trawler numbers, regulating fishing gear, and imposing spatial and seasonal closures. Despite these measures, biological information on industrial and small-scale fisheries, particularly along the northern coast of the Persian Gulf, remains limited. Consequently, catch-based data combined with biological analyses can provide valuable inputs for fisheries assessment and management. The family Carangidae is among the most species-rich and economically important groups of pelagic fishes in the Persian Gulf. The longnose trevally, Platycaranx chrysophrys (formerly Carangoides chrysophrys), is widely distributed across the Indian Ocean, Red Sea, Persian Gulf, and Western Pacific. Length-weight relationships are widely used as indicators of growth pattern, condition, and stock status, while the condition factor provides insight into fish well-being and habitat quality. Therefore, this study aimed to estimate the length-weight relationship and condition factor of P. chrysophrys in Hormozgan waters, providing baseline information for fisheries management. Materials and methods: A total of 42 specimens of P. chrysophrys were collected in December 2025 from Basaidu region, located in the northwestern waters of Qeshm Island, Persian Gulf. Sampling was conducted using a commercial bottom trawler. For biometric measurements, the total length (TL) of each individual was recorded to the nearest 1 mm using a graduated measuring board, and the total body weight (W) was determined to the nearest 0.01 g using a high-precision digital scale. The relationship between TL and W was estimated using the power curve equation: W=aLb, where “W” is the total weight (g), “L” is the total length (cm), “a” is the intercept (regression constant), and “b” is the slope (growth exponent). The parameters a and b were estimated via linear regression analysis after logarithmic transformation of the data: ln(W) = ln(a) + bln(L). Standard errors of the slope (b) and the coefficient of determination (R2) were calculated to evaluate the fit of the model. Fulton’s condition factor (K) was calculated to assess the overall health and well-being of the fish using the following formula: K=100 × W/L3, where “W” is the body weight (g) and “L” is the total length (cm). In addition, length frequency distribution was analyzed. The optimal number of length classes (k) was determined using Sturges’ rule: k = 1 + 3.322log10(n), where “n” is the total number of sampled fish. All statistical analyses, parameter estimations, and visualizations were performed using R software (version 4.4.2) and the stats package. Results: The examined specimens of P. chrysophrys (n = 42) exhibited a mean (± SD) total length of 37.60 ± 4.82 cm (range: 29.5-46.2 cm) and a mean (± SD) total weight of 613.10±195.23 g (range: 350-1100 g). The linear regression of the log-transformed data yielded the following length-weight relationship equation: lnW = ln (0.2622) + 2.13ln (L), which corresponds to the non-linear power equation: W = 0.2622L^2.1374. The coefficient of determination (R2 = 0.81) indicated a strong correlation between length and weight. The slope value (b = 2.13) was significantly lower than the isometric value of 3 (Student’s t-test: t = -5.087, p < 0.001), demonstrating a negative allometric growth pattern for P. chrysophrys in the study area. The mean Fulton’s condition factor for all sampled individuals was estimated 1.19 ± 0.24 (range: 0.87- 1.82). The length-frequency histogram showed that the length data followed an approximately normal distribution. The highest frequency of caught fish was observed in the 34-36 cm length class, representing approximately 24% (n = 10) of the total sampled population. Discussion and Conclusion: The present study showed that the sampled individuals of P. chrysophrys in Hormozgan waters were generally smaller than those reported for this species in previous studies from the Persian Gulf, Oman Sea, and Arabian Sea. The maximum observed total length in the present study was lower than previously reported values, and the dominant length class was 34-36 cm, whereas larger size classes were more abundant in earlier reports from neighboring regions. These patterns may suggest a temporal shift toward smaller individuals in the exploited stock. Several factors may contribute to such differences in size structure, including habitat conditions, food availability, environmental variability, and fishing pressure. However, given the relatively acceptable Fulton’s condition factor observed in the present study (mean K = 1.19), the reduced size of the sampled fish is less likely to reflect poor nutritional or environmental conditions alone. Instead, the observed pattern is more likely associated with increased fishing pressure and harvesting intensity in recent years, which may selectively remove larger individuals from the population. In addition, if the reported length at first maturity is applicable to this species, a considerable proportion of the sampled fish may have been below maturity size; however, this inference should be confirmed with direct maturity assessment. If confirmed by broader sampling, this pattern could have important implications for stock sustainability, because persistent removal of immature fish may reduce reproductive output and limit stock rebuilding capacity. The negative allometric growth pattern observed in this study (b < 3) further indicates that weight increased at a lower rate than length in the sampled individuals. Although this pattern may reflect species-specific growth characteristics, it may also be influenced by environmental conditions, season, sample size, and fishing selectivity. Therefore, caution is needed when comparing the present estimates directly with those of other regions or time periods. Overall, the results indicate that P. chrysophrys in Hormozgan waters is characterized by relatively small body size, a dominance of intermediate-to-small length classes, and acceptable somatic condition. These findings provide preliminary evidence of possible size reduction in the exploited stock and highlight the need for continued monitoring of size structure, maturity composition, and fishing pressure. Future studies based on larger sample sizes, multiple seasons, and broader spatial coverage are recommended to confirm these patterns and support effective management of this commercially valuable species in the Persian Gulf. Introduction: Reports from the Iranian Fisheries Research Organization (IFRO) suggest that fish stocks in the Persian Gulf are largely fully exploited or overexploited. Over the past decade, fishing effort in the region has increased, while management measures have focused mainly on limiting trawler numbers, regulating fishing gear, and imposing spatial and seasonal closures. Despite these measures, biological information on industrial and small-scale fisheries, particularly along the northern coast of the Persian Gulf, remains limited. Consequently, catch-based data combined with biological analyses can provide valuable inputs for fisheries assessment and management. The family Carangidae is among the most species-rich and economically important groups of pelagic fishes in the Persian Gulf. The longnose trevally, Platycaranx chrysophrys (formerly Carangoides chrysophrys), is widely distributed across the Indian Ocean, Red Sea, Persian Gulf, and Western Pacific. Length-weight relationships are widely used as indicators of growth pattern, condition, and stock status, while the condition factor provides insight into fish well-being and habitat quality. Therefore, this study aimed to estimate the length-weight relationship and condition factor of P. chrysophrys in Hormozgan waters, providing baseline information for fisheries management. Materials and methods: A total of 42 specimens of P. chrysophrys were collected in December 2025 from Basaidu region, located in the northwestern waters of Qeshm Island, Persian Gulf. Sampling was conducted using a commercial bottom trawler. For biometric measurements, the total length (TL) of each individual was recorded to the nearest 1 mm using a graduated measuring board, and the total body weight (W) was determined to the nearest 0.01 g using a high-precision digital scale. The relationship between TL and W was estimated using the power curve equation: W=aLb, where “W” is the total weight (g), “L” is the total length (cm), “a” is the intercept (regression constant), and “b” is the slope (growth exponent). The parameters a and b were estimated via linear regression analysis after logarithmic transformation of the data: ln(W) = ln(a) + bln(L). Standard errors of the slope (b) and the coefficient of determination (R2) were calculated to evaluate the fit of the model. Fulton’s condition factor (K) was calculated to assess the overall health and well-being of the fish using the following formula: K=100 × W/L3, where “W” is the body weight (g) and “L” is the total length (cm). In addition, length frequency distribution was analyzed. The optimal number of length classes (k) was determined using Sturges’ rule: k = 1 + 3.322log10(n), where “n” is the total number of sampled fish. All statistical analyses, parameter estimations, and visualizations were performed using R software (version 4.4.2) and the stats package. Results: The examined specimens of P. chrysophrys (n = 42) exhibited a mean (± SD) total length of 37.60 ± 4.82 cm (range: 29.5-46.2 cm) and a mean (± SD) total weight of 613.10±195.23 g (range: 350-1100 g). The linear regression of the log-transformed data yielded the following length-weight relationship equation: lnW = ln (0.2622) + 2.13ln (L), which corresponds to the non-linear power equation: W = 0.2622L^2.1374. The coefficient of determination (R2 = 0.81) indicated a strong correlation between length and weight. The slope value (b = 2.13) was significantly lower than the isometric value of 3 (Student’s t-test: t = -5.087, p < 0.001), demonstrating a negative allometric growth pattern for P. chrysophrys in the study area. The mean Fulton’s condition factor for all sampled individuals was estimated 1.19 ± 0.24 (range: 0.87- 1.82). The length-frequency histogram showed that the length data followed an approximately normal distribution. The highest frequency of caught fish was observed in the 34-36 cm length class, representing approximately 24% (n = 10) of the total sampled population. Discussion and Conclusion: The present study showed that the sampled individuals of P. chrysophrys in Hormozgan waters were generally smaller than those reported for this species in previous studies from the Persian Gulf, Oman Sea, and Arabian Sea. The maximum observed total length in the present study was lower than previously reported values, and the dominant length class was 34-36 cm, whereas larger size classes were more abundant in earlier reports from neighboring regions. These patterns may suggest a temporal shift toward smaller individuals in the exploited stock. Several factors may contribute to such differences in size structure, including habitat conditions, food availability, environmental variability, and fishing pressure. However, given the relatively acceptable Fulton’s condition factor observed in the present study (mean K = 1.19), the reduced size of the sampled fish is less likely to reflect poor nutritional or environmental conditions alone. Instead, the observed pattern is more likely associated with increased fishing pressure and harvesting intensity in recent years, which may selectively remove larger individuals from the population. In addition, if the reported length at first maturity is applicable to this species, a considerable proportion of the sampled fish may have been below maturity size; however, this inference should be confirmed with direct maturity assessment. If confirmed by broader sampling, this pattern could have important implications for stock sustainability, because persistent removal of immature fish may reduce reproductive output and limit stock rebuilding capacity. The negative allometric growth pattern observed in this study (b < 3) further indicates that weight increased at a lower rate than length in the sampled individuals. Although this pattern may reflect species-specific growth characteristics, it may also be influenced by environmental conditions, season, sample size, and fishing selectivity. Therefore, caution is needed when comparing the present estimates directly with those of other regions or time periods. Overall, the results indicate that P. chrysophrys in Hormozgan waters is characterized by relatively small body size, a dominance of intermediate-to-small length classes, and acceptable somatic condition. These findings provide preliminary evidence of possible size reduction in the exploited stock and highlight the need for continued monitoring of size structure, maturity composition, and fishing pressure. Future studies based on larger sample sizes, multiple seasons, and broader spatial coverage are recommended to confirm these patterns and support effective management of this commercially valuable species in the Persian Gulf.

https://janb.guilan.ac.ir/article_9811_03e417241589d4eab81d40c0814665ce.pdf

University of Guilan Aquatic Animals Nutrition 2980-8499 11 3 2025 09 23 Effect of Saccharomyces cerevisiae fermentation product on growth performance, survival and some hemato-immunological indices of Asian seabass (Lates calcarifer) Effect of Saccharomyces cerevisiae fermentation product on growth performance, survival and some hemato-immunological indices of Asian seabass (Lates calcarifer) 63 79 9756 10.22124/janb.2026.31927.1299 FA Marzieh Ghanbarpour Department of Fisheries, Faculty of Nano and Bioscience and Technology, Persian Gulf University, Bushehr, Bushehr, Iran Gholamreza Badzohreh Department of Fisheries, Faculty of Nano and Bio Science and Technology, Persian Gulf University, Bushehr, Iran , 0000-0001-9464-1789 Ebrahim Sotoudeh Department of Fisheries, Faculty of Nano and Bioscience and Technology, Persian Gulf University, Bushehr, Bushehr, Iran Vahid Morshedi Department of Fisheries and Biology, Persian Gulf Research Institute, Persian Gulf University, Bushehr, Bushehr, Iran Journal Article 2025 07 23 Introduction: For many years, antibiotics have been extensively applied in aquaculture, serving both to treat bacterial infections and to act as growth promoters. However, using antibiotics can negatively impact the environment and human health alike. For example, antibiotic use may result in the release of resistant bacterial strains into the environment, as well as the accumulation of drug residues in fish tissues. The EU has currently banned the use of antibiotics in animal nutrition. Consequently, efforts have been made to find an effective substitute for antibiotics in aquafeed. As eco-friendly alternatives to antibiotic reliance, various additives such as probiotics and postbiotics have been used to improve resistance to diseases in aquatic animals. Among different types of probiotic strains, Saccharomyces cerevisiae (yeast) and yeast fermentation products have been widely used in aquaculture since they enhance nonspecific immunity. Yeast fermentation products, as a product separated from inner yeast cells, could be a functional source of nutrients. S. cerevisiae fermentation product is a new fermented product. This product comprises a rich source of nutrients that can enhance the immunity and growth of fish. Materials and methods: In this experiment, the effects of various levels of S. cerevisiae fermentation product were investigated on the growth performance, survival, and some hematological and immunological responses in juvenile Asian seabass (Lates calcarifer). First, 240 healthy fish with an average body weight of 9.08 ± 0.41 g were randomly distributed to 12 polyethylene tanks with a capacity of 300 L and a density of 20 fish per tank. The fish were divided into four experimental groups in three replications and were fed four diets as follows: control (without adding S. cerevisiae fermentation product), FP1: 0.5%, FP2: 1%, and FP3: 2% S. cerevisiae fermentation product. The fish were fed three times a day until satiation for 8 weeks. At the end, fish were anesthetized for biometric measurements, and growth indices including weight gain percentage (WG), specific growth rate (SGR), protein efficiency ratio (PER), and feed conversion ratio (FCR) were calculated. Hemato-immunological parameters were assessed by collecting blood samples from the treatment and control groups at the end of the experiment. The data analysis in this study was performed using SPSS software version 21. Data were presented as the mean of 3 replicates ± standard deviation using the Duncan post-hoc test to compare means of each treatment. Results and Discussion: The results indicated that adding S. cerevisiae fermentation product in the diet significantly enhanced the growth performance of juvenile Asian seabass. In this study, WG, PER, SGR in FP1, FP2 and FP3 were significantly higher than in control. In contrast, the lowest FCR values of 1, 1.05, and 1.09 were recorded in FP3, FP2, and FP1, respectively, indicating a positive effect of these products on improving FCR. In the present study, growth indices showed a direct correlation with the level of added yeast, and all diets containing yeast resulted in increased growth indices, which could be attributed to enhance nutrient absorption. Bioactive compounds such as nucleotides, mannan oligosaccharides, and amino acids present in the fermentation products can enhance the palatability and food consumption in fish. The present results showed that hematological indices had no significant differences between the treatments and control group (P>0.05). Hematological alterations in fish may be different and depend on fish species, yeast types, experimental conditions, yeast concentrations, and the duration of trials. In the present study, the level of neutrophils in diets containing yeast was significantly higher than in the control group. The number of neutrophils in the treatment FP3 showed significant differences compared to the control group (P<0.05). Immunological assessments demonstrated significant increases in lysozyme activity, total protein, immunoglobulin levels, and albumin in the serum of Asian seabass fed with S. cerevisiae fermentation product (P<0.05). In this study, the increase in neutrophils in the blood may be responsible for the elevated lysozyme level in Asian seabass. Compounds such as beta-glucans and mannan oligosaccharides in fermented products can enhance the innate immune system in fish, resulting in increased levels of immune-active proteins Conclusion: The results of the present study showed that the growth performance of juvenile Asian seabass fed with diets containing different levels of S. cerevisiae improved. Additionally, the innate immune responses and antioxidant capacity of Asian seabass improved in this study. However, no significant changes were observed in the blood parameters. The findings of this study suggest that using 1-2% S. cerevisiae fermentation product in diets could improve the growth and immunity of juvenile Asian seabass. Introduction: For many years, antibiotics have been extensively applied in aquaculture, serving both to treat bacterial infections and to act as growth promoters. However, using antibiotics can negatively impact the environment and human health alike. For example, antibiotic use may result in the release of resistant bacterial strains into the environment, as well as the accumulation of drug residues in fish tissues. The EU has currently banned the use of antibiotics in animal nutrition. Consequently, efforts have been made to find an effective substitute for antibiotics in aquafeed. As eco-friendly alternatives to antibiotic reliance, various additives such as probiotics and postbiotics have been used to improve resistance to diseases in aquatic animals. Among different types of probiotic strains, Saccharomyces cerevisiae (yeast) and yeast fermentation products have been widely used in aquaculture since they enhance nonspecific immunity. Yeast fermentation products, as a product separated from inner yeast cells, could be a functional source of nutrients. S. cerevisiae fermentation product is a new fermented product. This product comprises a rich source of nutrients that can enhance the immunity and growth of fish. Materials and methods: In this experiment, the effects of various levels of S. cerevisiae fermentation product were investigated on the growth performance, survival, and some hematological and immunological responses in juvenile Asian seabass (Lates calcarifer). First, 240 healthy fish with an average body weight of 9.08 ± 0.41 g were randomly distributed to 12 polyethylene tanks with a capacity of 300 L and a density of 20 fish per tank. The fish were divided into four experimental groups in three replications and were fed four diets as follows: control (without adding S. cerevisiae fermentation product), FP1: 0.5%, FP2: 1%, and FP3: 2% S. cerevisiae fermentation product. The fish were fed three times a day until satiation for 8 weeks. At the end, fish were anesthetized for biometric measurements, and growth indices including weight gain percentage (WG), specific growth rate (SGR), protein efficiency ratio (PER), and feed conversion ratio (FCR) were calculated. Hemato-immunological parameters were assessed by collecting blood samples from the treatment and control groups at the end of the experiment. The data analysis in this study was performed using SPSS software version 21. Data were presented as the mean of 3 replicates ± standard deviation using the Duncan post-hoc test to compare means of each treatment. Results and Discussion: The results indicated that adding S. cerevisiae fermentation product in the diet significantly enhanced the growth performance of juvenile Asian seabass. In this study, WG, PER, SGR in FP1, FP2 and FP3 were significantly higher than in control. In contrast, the lowest FCR values of 1, 1.05, and 1.09 were recorded in FP3, FP2, and FP1, respectively, indicating a positive effect of these products on improving FCR. In the present study, growth indices showed a direct correlation with the level of added yeast, and all diets containing yeast resulted in increased growth indices, which could be attributed to enhance nutrient absorption. Bioactive compounds such as nucleotides, mannan oligosaccharides, and amino acids present in the fermentation products can enhance the palatability and food consumption in fish. The present results showed that hematological indices had no significant differences between the treatments and control group (P>0.05). Hematological alterations in fish may be different and depend on fish species, yeast types, experimental conditions, yeast concentrations, and the duration of trials. In the present study, the level of neutrophils in diets containing yeast was significantly higher than in the control group. The number of neutrophils in the treatment FP3 showed significant differences compared to the control group (P<0.05). Immunological assessments demonstrated significant increases in lysozyme activity, total protein, immunoglobulin levels, and albumin in the serum of Asian seabass fed with S. cerevisiae fermentation product (P<0.05). In this study, the increase in neutrophils in the blood may be responsible for the elevated lysozyme level in Asian seabass. Compounds such as beta-glucans and mannan oligosaccharides in fermented products can enhance the innate immune system in fish, resulting in increased levels of immune-active proteins Conclusion: The results of the present study showed that the growth performance of juvenile Asian seabass fed with diets containing different levels of S. cerevisiae improved. Additionally, the innate immune responses and antioxidant capacity of Asian seabass improved in this study. However, no significant changes were observed in the blood parameters. The findings of this study suggest that using 1-2% S. cerevisiae fermentation product in diets could improve the growth and immunity of juvenile Asian seabass.

https://janb.guilan.ac.ir/article_9756_fbeebfc1031a96ef6f09a2fd2a2e4eae.pdf

University of Guilan Aquatic Animals Nutrition 2980-8499 11 3 2025 09 23 Assessment of the Zn, Pb, Cd and Hg concentrations in muscle of wild common carp (Cyprinus carpio) in Guilan Province, North Iran Assessment of the Zn, Pb, Cd and Hg concentrations in muscle of wild common carp (Cyprinus carpio) in Guilan Province, North Iran 81 93 9826 10.22124/janb.2026.33853.1309 FA Mehdi Taheri Department of Aquatic Animal, Veterinary Medicine College, Ka.C., Islamic Azad University, Karaj, Alborz, Iran Babak Shoaibi Omrani Department of Aquatic Animal, Veterinary Medicine College, Ka.C., Islamic Azad University, Karaj, Alborz, Iran Soheil Alinezhad, Institute of Agricultural Education and Extension, Agricultural Research Education and Extension Organization (AREEO), Tehran, Tehran, Iran Journal Article 2025 07 27 Introduction: Industrial expansion and increased activity in coastal areas, coupled with the discharge of wastewater and pollutants, have caused marine pollution, particularly in enclosed environments like the Caspian Sea, where pollutants accumulate due to evaporation. Heavy metals, stable and non-biodegradable, pose significant health risks to humans and aquatic life by contaminating marine environments and fish, a key part of the human food chain. Factors such as fish age, size, sex, feeding habits, ecological needs, heavy metal concentrations in water and sediment, duration of fish residence, fishing season, and water chemistry (salinity, hardness, temperature) all influence heavy metal accumulation in fish organs. Heavy metals and other pollutants accumulate in aquatic organisms and can transfer to humans, posing health risks. The toxicity depends on the metal type and concentration; lead, arsenic, mercury, and cadmium are particularly hazardous due to low tolerance limits. This study focused on wild common carp in Guilan Province (Iran), a valuable species that feeds on bottom sediments. Carp's feeding habits make them prone to higher heavy metal accumulation compared to surface-dwelling fish, highlighting the importance of studying contamination in wild-caught fish, considering diet, habitat, and species variations. Materials and methods: A total of 24 wild common carp weighing 1450 ± 161 g were randomly collected in April 2022 from fish markets in the cities of Astara, Hashtpar, Anzali, Rasht, Kelachay, and Kiashahr in Guilan Province. In the laboratory, after biometric measurements and recording of total and standard lengths as well as weight, a 100-gram portion of pectoral fin muscle from each specimen was separated, coded, and stored at −20 °C until digestion. Heavy metals were measured using an atomic absorption spectrometer. Descriptive statistics and Kolmogorov–Smirnov tests assessed data normality. One-Way ANOVA (SAS v9.4) compared quantitative variable means across independent groups. T-tests identified differences between independent group means. Duncan's multiple range test (95% confidence) performed group mean comparisons. Partial correlation analyzed relationships between quantitative traits and heavy metal accumulation. Results: The findings of this study showed no significant differences in heavy metal accumulation between male and female fish, nor between heavy metal concentrations and the measured biometric characteristics of the specimens (P > 0.05). The mean concentrations of zinc (24.73 ± 14.24 µg/g dry weight), cadmium (0.003 ± 0.00020 µg/g), lead (0.0252 ± 0.001 µg/g) and mercury (0.0842 ± 0.0659 µg/g) were found to be well within the permissible limits of international standards (FAO/WHO) and the Iranian national standard (Iran Veterinary Organization). Discussion: Fish feeding habits significantly impact contaminant accumulation, with variations observed even among those in similar aquatic environments. For bottom-feeding common carp, sediment is a key source of heavy metal accumulation. This study found that common carp in the examined regions are safe, with zinc, lead, cadmium, and mercury levels below international standards. Sediment contamination can transfer to these organisms and then to the fish. The low contamination levels in this study suggest that sediments and small benthic organisms in the region also have relatively low levels of zinc, cadmium, lead, and mercury. Introduction: Industrial expansion and increased activity in coastal areas, coupled with the discharge of wastewater and pollutants, have caused marine pollution, particularly in enclosed environments like the Caspian Sea, where pollutants accumulate due to evaporation. Heavy metals, stable and non-biodegradable, pose significant health risks to humans and aquatic life by contaminating marine environments and fish, a key part of the human food chain. Factors such as fish age, size, sex, feeding habits, ecological needs, heavy metal concentrations in water and sediment, duration of fish residence, fishing season, and water chemistry (salinity, hardness, temperature) all influence heavy metal accumulation in fish organs. Heavy metals and other pollutants accumulate in aquatic organisms and can transfer to humans, posing health risks. The toxicity depends on the metal type and concentration; lead, arsenic, mercury, and cadmium are particularly hazardous due to low tolerance limits. This study focused on wild common carp in Guilan Province (Iran), a valuable species that feeds on bottom sediments. Carp's feeding habits make them prone to higher heavy metal accumulation compared to surface-dwelling fish, highlighting the importance of studying contamination in wild-caught fish, considering diet, habitat, and species variations. Materials and methods: A total of 24 wild common carp weighing 1450 ± 161 g were randomly collected in April 2022 from fish markets in the cities of Astara, Hashtpar, Anzali, Rasht, Kelachay, and Kiashahr in Guilan Province. In the laboratory, after biometric measurements and recording of total and standard lengths as well as weight, a 100-gram portion of pectoral fin muscle from each specimen was separated, coded, and stored at −20 °C until digestion. Heavy metals were measured using an atomic absorption spectrometer. Descriptive statistics and Kolmogorov–Smirnov tests assessed data normality. One-Way ANOVA (SAS v9.4) compared quantitative variable means across independent groups. T-tests identified differences between independent group means. Duncan's multiple range test (95% confidence) performed group mean comparisons. Partial correlation analyzed relationships between quantitative traits and heavy metal accumulation. Results: The findings of this study showed no significant differences in heavy metal accumulation between male and female fish, nor between heavy metal concentrations and the measured biometric characteristics of the specimens (P > 0.05). The mean concentrations of zinc (24.73 ± 14.24 µg/g dry weight), cadmium (0.003 ± 0.00020 µg/g), lead (0.0252 ± 0.001 µg/g) and mercury (0.0842 ± 0.0659 µg/g) were found to be well within the permissible limits of international standards (FAO/WHO) and the Iranian national standard (Iran Veterinary Organization). Discussion: Fish feeding habits significantly impact contaminant accumulation, with variations observed even among those in similar aquatic environments. For bottom-feeding common carp, sediment is a key source of heavy metal accumulation. This study found that common carp in the examined regions are safe, with zinc, lead, cadmium, and mercury levels below international standards. Sediment contamination can transfer to these organisms and then to the fish. The low contamination levels in this study suggest that sediments and small benthic organisms in the region also have relatively low levels of zinc, cadmium, lead, and mercury.

https://janb.guilan.ac.ir/article_9826_cd4965cef79f517ad048bddcdf0be9b5.pdf