Protozoan Parasites of Iranian Freshwater Fishes: Review, Composition, Classification, and Modeling Distribution.

This article investigates the occurrence and distribution of parasitic protozoa of Iranian freshwater fishes (both farmed and wild). Our search shows 26 known parasitic protozoan species were recorded from 52 freshwater fish species across different ecoregions of Iran. Most of these fish are edible. While none of the identified protozoan parasites are of zoonotic importance, our study does not exclude presence of zoonotic species in Iranian fishes. Present data suggest the northern and western regions of the country are the main macrohabitat of protozoa (35 parasitic records reported), with the greatest concentration of parasitic protozoa occurring in the Urmia basin in Iran's northwest. The clustered distribution pattern of protozoa among freshwater fish was also more evident in the northern and western parts of the country. The gills and skin were the most infected microhabitats for parasitic protozoa. The highest number of parasites was observed in the fish family Cyprinidae with nine species found in the native fish, Capoeta capoeta. The most diverse host range was observed in the holotrich ciliate, Ichthyophthirius multifiliis isolated from 46 cyprinid species in 39 different locations. However, due to the great richness of fish and extreme habitat diversity, parts of the parasite fauna of Iranian freshwater fish are still poorly understood. Furthermore, current and future changes in climate and environmental parameters, and anthropogenic interventions are likely to affect fish hosts and their parasites.

A systematic review of the concentration of potentially toxic elements in fish from the Persian Gulf: A health risk assessment study.

Fish as a critical food source is responsible for supplying nearly 20% of the average per capita animal protein for 3.2 billion people worldwide. However, oral exposure to potentially toxic elements (PTE) such as mercury (Hg), cadmium (Cd), lead (Pb), and arsenic (As) through marine fish consumption can cause health risks in consumers. This study aimed to collect information among databases (2000-2020), including ScienceDirect, PubMed, SCOPUS, EMBASE, and Google Scholar, regarding the concentration of PTEs in different types of fish from the Persian Gulf. In this regard, thirty articles containing 266 samples were included in the current systematic review. In addition, the non-carcinogenic risk caused by ingestion of PTEs via consumption of fish was calculated. The average PTE concentrations in fish muscles were presented in the following order: As (0.37 mg/kg ww) > Pb (0.20 mg/kg ww) > Cd (0.17 mg/kg ww) > Hg (0.13 mg/kg ww). However, the mean concentration of PTEs was below the defined level by the World Health Organization, and the findings revealed that the calculated average daily dose (ADD) for Cd and Pb in Iranian children and adult consumers was lower than the reference dose (RfD), whereas the ADD of Hg was higher than the RfD for children consumers. The total target hazard quotient for Iranian and children consumers was >1. The excess lifetime cancer risk values for Pb were safe, unlike those for Cd, which were in an unsafe range (>10-4) for consumers.

The Effects of Dietary Thyme Oil (Thymus vulgaris) Essential Oils for Common Carp (Cyprinus carpio): Growth Performance, Digestive Enzyme Activity, Antioxidant Defense, Tissue and Mucus Immune Parameters, and Resistance against Aeromonas hydrophila.

This study evaluated the effects of dietary supplementation of thyme (Thymus vulgaris) essential oil (TVO) on growth performance, digestive enzymes, biochemical parameters, hematological indices, liver enzymes, and pathogen resistance in common carp (Cyprinus carpio). Triplicate groups of fish (15.36 ± 0.10 g) were fed daily with diets supplemented with TVO at 0, 0.5, 1, and 2 percent for 60 days then challenged with Aeromonas hydrophila. The results determined that supplementation of thyme resulted in significantly higher final body weights (FBW) and lower feed conversion ratios (FCR). Furthermore, no mortality was observed in the thyme-supplemented treatments. Regression analysis showed that fish growth parameters were polynomially related to dietary TVO levels. The optimum dietary TVO level, based upon the varied growth parameters, was 1.344 to 1.436%. Digestive enzymes activity, including amylase and protease, significantly increased in fish fed the supplemented diets. The thyme-supplemented diets also significantly increased the biochemical parameters, including total protein, albumin, and acid phosphatase (ACP), compared to the control group. We also observed significant increases in hematological indices, including red blood cells (RBC), white blood cells (WBC), hematocrit (Hct), and hemoglobin (Hb) in common carp fed diets containing thyme oil (P < 0.05). Liver enzymes activity including alanine aminotransferase (ALT), alkaline phosphatase (ALP), and aspartate aminotransferase (AST) was also reduced (P < 0.05). Immune parameters, including total protein and total immunoglobulin (total Ig) levels, alternative complement pathway hemolytic (ACH50), lysozyme, protease, and ALP in the skin mucus, and lysozyme, total Ig, and ACH50 in the intestine were higher (P < 0.05) in TVO-supplemented fish. Catalase (CAT), superoxide dismutase (SOD), glutathione reductase (GR), and glutathione peroxidase (GPx) in the liver were also elevated (P < 0.05) in TVO administered groups. Lastly, thyme-supplementation resulted in higher survival rates after the A. hydrophila challenge compared to the control (P < 0.05). In conclusion, dietary inclusion of thyme oil (1 and 2%) effectively improved fish growth, immune systems, and resistance to A. hydrophila.

The effects of combined inclusion of Malvae sylvestris, Origanum vulgare, and Allium hirtifolium boiss for common carp (Cyprinus carpio) diet: Growth performance, antioxidant defense, and immunological parameters.

The present study aimed to investigate the effects of a mixture of three medicinal plants extracts (COP: common mallow (Malvae sylvestris), oregano (Origanum vulgare), and Persian shallot (Allium hirtifolium boiss)) on growth, hematological indices, immunological parameters, liver antioxidant, and digestive enzyme activity of common carp (Cyprinus carpio). Accordingly, 540 common carp fingerlings were randomly allotted to 18 fiberglass tanks, including six treatments each in triplicate. Fish were fed with experimental diets supplemented with 0, 0.5, 1, 2, 3, and 5% of the herbal mixture. After 60 days, the effects on growth performance, antioxidant, and immunological parameters were evaluated. According to the results, the highest final weight was observed in the fish fed 2 and 3% of the herbal mixture. Also, the feed conversion ratio (FCR) showed a significant decrease in fish treated with the herbal mix, so that the lowest FCR was observed in the treatment 1%. Hematological examinations such as red blood cells (RBC), white blood cell (WBC), and hemoglobin showed significant changes between different parameters compared to the control group. The highest protein content was observed in the fish supplemented with 2, 3, and 5% herbs. Besides, in contrast to glucose, the cortisol level showed a significant decrease compared to the control group. The digestive enzymes (Amylase, Lipase, and Protease) were significantly higher in 2 and 3% treatments than in the control group. Also, a significant difference was found in Superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR) activity, and malondialdehyde (MDA) content between the experimental and control treatments. Examination of liver enzymes (and alanine aminotransaminase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP)) showed a significant difference in herbal mixture treatments with the control group, according to which the lowest amount of these enzymes was recorded in 2 and 3% herb supplemented fish. Herbal mix resulted in higher mucosal and intestinal immunity parameters, including total immunoglobulin (total Ig), lysozyme, alternative complement activities (ACH50), protease, and ALP. According to the results, supplementing the diet with a mixture of the COP can significantly improve growth parameters, stimulate the innate immune system, and improve antioxidant defenses and liver health of common carp.

The Synergistic Effects of Combined Use of Mentha longifolia, Thymus carmanicus, and Trachyspermum copticum on Growth Performance, Feed Utilization, and Expression of Key Immune Genes in Rainbow Trout (Oncorhynchus mykiss).

Medicinal plants exhibit remarkable positive effects on different aspects of fish physiology. This study aimed to evaluate the possible impact of a combination of plants (Mentha longifolia, Thymus carmanicus, and Trachyspermum copticum) on growth performance, immune responses and key immune gene expression of rainbow trout. For this purpose, four diets were designed, including zero, 0.25, 0.5, and 1% of a mixture of plants per kg of diet, representing dietary treatments of control, T1, T2, and T3, respectively. Two hundred forty fish (weighing 23.11 ± 0.57 g) were fed 3% of body weight twice a day for 45 days. The results showed that growth parameters of weight gain (except for T1) and FCR were significantly improved in fish receiving all levels of plants, with T3 showing the best growth results. Digestive enzymes activities were notably increased in T1 and T2 compared to the control. Stress biomarkers (glucose and cortisol) were significantly decreased in T1 and T2, while T3 was not significantly different from the control. Immunological responses were significantly improved in T2, while T1 andT3 did not show a statistical difference in terms of lysozyme activity. Catalase activity was noticeably decreased in T1, although superoxide dismutase and malondialdehyde were highest in T2. Immune-related genes were significantly up-regulated in T3 compared to other treatments. Also, antioxidant enzyme coding genes were strongly up-regulated in T2 and T3. Overall, the present results suggest that 1% inclusion of the mixture of M. longifolia, T. carmanicus, and T. copticum (T2) can be used to improve the growth and immunity of rainbow trout.

Assessment of health risk from heavy metal contamination of shellfish from the Persian Gulf.

The present study assessed the risk of consumption of shrimp and lobster contaminated with mercury, arsenic, cadmium, and lead from the Persian Gulf. The concentrations of mercury, arsenic, lead, and cadmium in shrimp was 62.5, 178.2, 325.2, and 193.5 µg kg(-1) and in lobsters was 53.2, 103.9, 640.6, and 163.1 µg kg(-1), respectively. The maximum daily consumption of shrimp and lobster was calculated to estimate health risks associated with their consumption. The results showed that the maximum allowable consumption of shrimp and lobster was 18-140 g/day for mercury, 33-214 g/day for arsenic, 59-454 g/day for cadmium, and 72-916 g/day for lead. The concentration of metals was within recommended limits for human consumption with the exception of lead, which was found to be above acceptable levels and represents a health risk.

Mercury and arsenic in green tiger shrimp from the Persian Gulf.

Mercury and arsenic pollution has been recognized as a potential environmental and public health problem for over 40 years. The major source of exposure to mercury and arsenic for humans is the ingestion of sea food. Concentrations of mercury and arsenic in the muscle samples of green tiger shrimp (Penaeus semisulcatus) from the Persian Gulf were determined by cold vapor atomic absorption spectrometry. Concentrations of metals in muscle samples were 49-115 µg kg(-1) for mercury, 115-131 µg kg(-1)for arsenic, with means of 82.7 and 251.6 µg kg(-1), respectively. Statistical analysis showed no significant difference of mercury and arsenic concentration in shrimp muscles between selected stations (Bushehr, Khuzestan, and Hormozgan provinces). No significant difference was found among heavy metal contents of male and female shrimps. The results of this study indicate that the green tiger shrimp from the Persian Gulf have concentrations well below the maximum permissible levels for mercury (500 µg kg(-1)) and arsenic (6000 µg kg(-1)), according to international standards, with no health risk of consumers.

Health risk assessment of mercury and arsenic associated with consumption of fish from the Persian Gulf.

Concentrations of mercury and arsenic in fish from the Persian Gulf were determined by graphite furnace atomic absorption spectrometry. Concentrations of the metals in muscle samples were 0.049-0.402 µg g(-1) for mercury and 0.168-0.479 µg g(-1) for arsenic, with means of 0.133 and 0.312 µg g(-1), respectively. The maximum daily consumption rate (grams per day) and meal consumption limit (meals per month) was calculated to estimate health risks associated with fish consumption. According to the results, the maximum allowable consumption rate varies between 8-56 and 15-96 g/day base on mercury and arsenic content, respectively. The results of this study indicate that the concentration of mercury and arsenic is well below the maximum permissible levels for mercury (0.5 µg g(-1)) and arsenic (6 µg g(-1)) according to international standards.

Determination of mercury in some freshwater fish species from Chahrmahal va Bakhtyari Province, Iran and potential limits for human consumption.

Concentrations of mercury in four freshwater fish species from Gandoman and Sooleghan Lagoons and Beheshtabad River were determined by cold vapor atomic absorption spectrometry. Concentrations of mercury in muscle of 90 fish ranged from 21 to 31 µg kg(-1) (mean = 26 µg kg(-1)). Statistical analysis showed no statistical relationship between mean mercury concentration and fish species, although concentration of mercury in different seasons and habitats was statistically different (p < 0.05). The results indicated that fish from Gandoman and Sooleghan Lagoons and Beheshtabad River have concentrations well below the maximum permissible levels of mercury according to international standards with no health risk for consumers.

Mercury, arsenic, cadmium and lead in lobster (Panulirus homarus) from the Persian Gulf.

Concentrations of four toxic metals including mercury, arsenic, lead and cadmium in lobster (Panulirus homarus) muscles from the Persian Gulf were determined by graphite furnace atomic absorption spectrometry. Heavy metals concentrations in muscle samples were 32-73 µg/kg for mercury, 118-275 µg/kg for arsenic, 379-1120 µg/kg for lead and 101-401 µg/kg for cadmium, with means of 48.7 µg/kg, 184.3 µg/kg, 629.4 µg/kg and 2 50.6 µg/kg, respectively. Most of the heavy metals studied in the edible muscle tissue in P. homarus ranged within the recommended limits for human consumption, except lead, which was found to be above the acceptable level and represents a health risk for consumers.