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Background: In natural waters and/or aquaculture facilities, fish are often exposed to chromium waste and demonstrate cumulative deleterious effects. To our knowledge, there are no studies concerning the effects of trivalent Cr on C. carpio hematology. This study presents hematological and some biochemical parameters of common carp, Cyprinus carpio, affected by sublethal concentration of trivalent chromium.
 Methods: The fish in the experimental aquaria (three replicates each) were exposed to a sublethal chromium chloride concentration of 2 mg L−1, which was prepared as stock solution and added depending on the volume of the aquaria to obtain the required concentration. After a period of 28 days, parameters such as hematocrit (Hct), hemoglobin (Hb), lymphocytes (Lym), neutrophils (Neu), total protein (TP), albumin, immunoglobulin M (IgM), glucose, red and white blood cells (RBC and WBC), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and mean corpuscular hemoglobin concentration (MCHC) were examined.
 Results: Chromium exposure for 28 days significantly (P<0.05) reduced the amounts of Hct, Hb, RBC, WBC, MCH, and MCHC, whereas albumin and glucose significantly (P<0.05) increased in the examined fish as opposed to the control. The levels of Lym, Neu, MCV, IgM, and TP were not significantly different (P>0.05) between the Cr-exposed fish and the control.
Conclusion: Hematological indices of fish, caused by chromium toxicity to C. carpio, can be secondary responses to toxicants, including exposure to low concentrations of heavy metals, which reflect the launch of stress reaction in the affected fish.

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Background: Evaluation on the toxicity of two mainly contaminant heavy metals, cadmium (Cd) and lead (Pb) through the food chain was the aim of this study.

Methods: A total number of 270 healthy common carp (4±1.14 g) in April, 2015 transported to the Khatam Alanbia University of Technology, Behbahan, Iran. Fishes were divided into three groups and transferred to the 20 L aquaria each containing 30 juveniles. The first group (control) fed by metal-free Artemia fransiscan anauplii throughout the experiment. The second and third groups were feeding by Cd and Pb (1.5 mg/L free ion) contaminated nauplia, respectively. The experimental study was carried out for three weeks and sampling was done in 4th, 7th, 14th and 21st days. Finally, the alterations in plasma biochemical responses were determined.

Results: Alanine aminotransferase and aspartate aminotransferase activities increased in response to feeding Pb-contaminated nauplia. Creatine phosphokinase activity showed significant increase in fourth day about both Cd and Pb and at the end of experiment only in Cd treatment (P<0.05). Cholesterol and triglyceride were increased significantly only for Pb (P<0.05). Plasma glucose and creatinine levels increased by both heavy metals compared to the control but glucose just remained high only for Pb at the end of the experiment. Total protein, albumin and globulin were significantly declined in both metal contaminated groups (P<0.05).

Conclusion: It seems Pb had a greater toxicity than Cd through the food chain and it may be due to its more trophic transfer than Cd.

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Background: Paraquat is a non-selective contact herbicide, widely used to control weeds in agriculture farms and aquatic plants in surface waters. Paraquat can have adverse effects on the health of aquatic organisms. The aim of this study was to detect the alterations in the blood biochemical parameters of common carp exposed to sub-lethal concentrations of commercial formulations of paraquat.

Methods: The fish were exposed to sub-lethal concentrations (0.2 and 0.4 mg.L^-1) of paraquat for 21 days. Biochemical parameters including glucose, total protein, albumin, globulin, creatinine, triglyceride and cholesterol levels, and aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), creatine phosphokinase (CK), alkaline phosphatase (ALP) and γ-glutamyl transferase (GGT) activities were measured.

Results: A significantly increase was observed in AST activity in fish exposed to 0.4 mg.L^-1 paraquat. Paraquat caused a significant (P < 0.05) increase in plasma ALT, LDH and CPK activities and plasma creatinine levels. Although ALP activity significantly (P < 0.05) increased in fish exposed to 0.2 mg.L^-1 paraquat, the fish exposed to 0.4mg.L^-1 paraquat exhibited a significant (P < 0.05) decrease in ALP activity. A significant (P < 0.05) decrease in GGT activity, total protein, albumin and globulin levels as well as cholesterol and triglyceride levels was observed in fish exposed to sub-lethal concentrations of paraquat.

Conclusion: Exposure to sub-lethal concentrations of paraquat may cause changes in blood biochemical parameters in common carp.

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Background: We investigated the effects of different dose of aflatoxins, secondary toxic metabolites produced by Aspergillus flavus, on some biochemical parameters in kidney of common carp (Cyprinus carpio).

Methods: This study was done in Aquaculture and Biology Laboratory of Behbahn Khatam Alanbia University of Technology, Behbahan, Iran in 2015.  Fishes were distributed into five groups: Group I-III was fed contaminated diets with 0.5, 0.7 and 1.4 mg kg^-1 feed, respectively. Group IV was fed contaminated diets with extraction solution (methanol, acetone, and diluted water) as a positive control. Control group received normal feed (Group V). After 21 d of experiment, activities of cellular enzymes and oxidative stress biomarker were evaluated.

Results: Aflatoxins (0.7 and 1.4 mg kg^-1) caused a significant increase in ALT activity. Although, significant increase of LDH activity (P<0.05) were found in kidney of fish fed diet contaminated with 0.5 mg kg^-1 of aflatoxins, LDH activity was significantly decreased in kidney of fish fed diet contaminated with 0.7 and 1.4 mg kg^-1 of aflatoxins. A significant increase (P<0.05) were observed in MDA levels and CAT activity in kidney of fish fed diet contaminated with different concentrations of aflatoxins for 21 d. The total antioxidant levels, AST and ALP activities in kidney of fish were significantly reduced (P<0.05) on the 21st day following aflatoxins administration.

Conclusion: Diets containing certain concentrations of aflatoxins (0.5, 0.7 and 1.4 mg kg^-1 feed) made oxidative damage to kidney tissue, including changes in oxidative stress biomarker and biochemical parameters.

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Background: Histological studies in organs like hepatopancreas and gill of the freshwater fish, Cyprinus carpio, were made to assess tissue damage due to sub-lethal concentration of cadmium after a long exposure period.
Methods: This study was conducted in University of Tehran, in 2013. The fish were divided into two groups in 1000 litre fiberglass tanks supplied with dechlorinated water [hardness 302.6 mg CaCo₃/l, pH 7, O₂ 7.8 mg/L and temperature 15 ± 2 ºC] and continuous aeration. Group 1 was without any cadmium considered as control group. Group 2 was exposed to 30 ppb CdCl₂ (Merck) containing 7.8 ppb cadmium. The tissue samples from: hepatopancreas, gill were collected 30 days post exposure and processed by histological procedures.
Results: The main lesions in cadmium exposed groups were: (a) pancreatitis necrosis in endocrine part of pancreas (b) cholangitis and necrosis in liver parenchyma (c) hypertrophy, fusion and telangiectasia in secondary lamellae
Conclusion: Cadmium chloride at low concentration can induce pathological alterations in hepatopancreas and gill of common carp.

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Background: To assess the toxicity of environmental pollutants in fish, there are different physiological parameters including histology. This study aimed to investigate the effect of prebiotic dietary supplement on fish immune response after exposure to toxicant.
Methods: The study was conducted in the Gorgan University of Agricultural and Natural Resources aquaculture Laboratory in 2017. Common carp species were obtained and exposed to 2 ppm, 3 ppm, 6 ppm Abamectin as a toxicant. Prebiotic isomalto-oligosaccharides added to diet with spray method as 1 g/kg and histopathological examinations were done after 60 d experiment. There were no significant differences between aquariums in water quality during the test and no mortality and injuries were observed during accumulation.
Results: The Abamectin caused some lesions such as vacuolization latest, bleeding, necrosis, degeneration of the epithelium, the destruction of the villi in the intestine, destruction of liver cells, ascites, hemorrhage, necrosis and nuclear karyolysis in the liver and lymphocytes penetration and degradation of intestinal epithelium in intestine. Maximum lesions observed in 6-ppm toxicant concentration.
Conclusion: The isomalto-oligosaccharides probiotics was not successful in stimulating the immune system and reducing adverse effect of toxicant in common carp, significantly. However, usage of this prebiotic could be useful in some cases.

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Background: We have come across the plant secondary metabolites having pesticidal properties being used in the form of pesticides. In this study, we used one of newly available and plant metabolite used as pesticide in wide agricultural fields – Karanjin, obtained from seeds of plant Pongamia pinnata.
Methods: The study was conducted during the month of March 2016 at the Department of Zoology, Osmania University. The fish common carp- Cyprinus carpio was exposed to sub-lethal concentration of karanjin i.e., 1/10^th of 96 h LC50 value (0.28 ppm) for a period of 21 d. Moreover, at 24 h, 7 d, 14 d and 21 d, the peripheral blood of both control and exposed group fishes were studied for the presences of micronuclei and other nuclear abnormalities.
Results: The micronuclei were completely absent, i.e., were not seen during the sub-lethal exposure period. There were seen nuclear abnormalities such as blebbed nuclei (BN), notched nuclei (NN), differently shaped nuclei (DSN), pear-shaped nuclei (PSN), circular nuclei (CN), lobed nuclei (LN) and Karyolysed nuclei (KN). The control group showed few nuclear abnormalities.
Conclusion: During the sub-lethal exposure, as the days of exposure increased, the types of aberrations and their number also increased.

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Background: Present study was conducted to measure the level of total mercury (tHg) in sediments, benthos and benthivorous fish (i.e., common carp) for determining Biota (Benthos)-Sediment Accumulation Factor (BSAF), as well as Biomagnification Factor (BMF) of tHg between two trophic levels of benthos and benthivorous fish caught from Sanandaj Gheshlagh Reservoir (SGR) in the west of Iran.
Methods: Samples of sediments and benthos biomasses were collected from three sampling stations. Common carps were captured around the selected stations during July to December 2010.
Results: Means accumulated tHg (±SE) in sediments, benthos masses and muscle tissue of common carp were 117.66±9.72, 94.3±5.02 and 233.21±20.67 ng g^-1 dry weight, respectively. Means accumulated tHg in benthos masses and muscle tissue of the common carp during the studying months showed no significant differences (P>0.05), while it was significantly differed in sediment samples (P<0.05). Results showed that there were statistically significant differences between accumulated tHg between sediment and benthos mass samples collected from the study sites (P<0.05).
Conclusion: During the study, all calculated BSAF measurements were less than one, indicating transmission of mercury from sediment to benthos was not considerable. However, mercury BMF_s was higher than one, denoting mercury biomagnification occurred from the benthos trophic level to the higher trophic level (i.e., common carp) in study site. Hence, the health considerations have to be taken in to the account for consumption of fishery products of SGR.
 

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