BACKGROUND: Titanium dioxide nanoparticles (TiO2NPs) are used in many commercial products, including paints, sunscreens and edible products, and can be used directly and indirectly in aquaculture. Due to the widespread application of these nanoparticles, the investigation of their possible effects on aquatic organisms is necessary. OBJECTIVES: The purpose of this study was to investigate the histopathological effects of waterborne TiO2NPs on the gills, liver and intestine of Caspian trout. METHODS: In this study, 126 fish (27.46±4.3 g) were tested in six concentrations of TiO2NPs (0, 0.01, 0.1, 1, 10 and 100 mg/L) for 4 days. At the end of the experiment, tissues were evaluated to determine the effects of tissue damage caused by TiO2NPs. RESULTS: The 96-h exposure to TiO2NPs did not cause fish mortality. Accordingly, investigated TiO2NPs are classified as "relatively non-toxic". The most important tissue changes caused by short-term exposure to TiO2NPs were hyperplasia and hypertrophy, lamellar fusion, necrosis in gills; foci of melanomacrophage deposits, aggregation of blood cell, hepatocytes with pycnotic nuclei, vacuolation, necrosis in liver; thickening of lamina propria, erosion of villi and necrosis in intestine. CONCLUSIONS: Although TiO2NPs are relatively non-toxic,  due to the tissue damage observed, these nanoparticles can be harmful to Caspian trout.

BACKGROUND: Diazinon is an organophosphate pesticide which is widely used in paddy fields located in northern parts of Iran, though it is prohibited to be used in many countries. OBJECTIVES: The purpose of the present study was to investigate sublethal effects of diazinon on blood parameters of common bream Abramis brama. METHODS: In sublethal toxicity test, fish were exposed to diazinon concentrations of 0.04, 0.36, 0.73 and 1.46 mg/l for 14 days and their hematological parameters including WBCs, white cell differential count, RBCs, Hct, Hb, MCV, MCH and MCHC were studied.  RESULTS: The results of sublethal toxicity indicated that by increase of toxicant concentration a significant decrease was appeared in WBCs, RBCs, Hct, Hb and MCH both after 7 and 14 days (p<0.05). After 7 days a significant decrease was observed in lymphocytes count which accounted for about %81 of the control group. The neutrophils count was also face the same reduction so that after 14 days of diazinon exposure, the neutrophils counted decreased to about %85 of control group. CONCLUSIONS: Regarding the toxicity of diazinon on various hematological parameters and the diazinon concentration in Iranian waters and considering the fish habitat in the waters which are connected to the Caspian Sea it suggests that the pesticide diazinon affect the fish survival.

BACKGROUND Agricultural pesticides can cause environmental pollution and damage to aquatic organisms. Bensulfuron-methyl is a widely used herbicide in agricultural fields, especially rice fields. Despite the solubility of Bensulfuron-methyl in water and its entry into aquatic environments, limited research has been conducted on the toxicity of this herbicide in aquatic organisms.OBJECTIVES: This study aims to investigate the effects of chronic toxicity of Bensulfuron-methyl in common carp (Cyprinus carpio).METHODS: The fish were divided into four groups. Group 1 was considered as a control, and groups 2, 3, and 4 were exposed to 10 %, 20 %, and 30 % of the 96 h lethal concentration 50 of Bensulfuron-methyl equal to 0, 0.162, 0.324 and 0.486 g/L.  After 21 days, blood samples, serum levels, and liver tissue of fishes were analyzed.RESULTS: The number of white blood cells increased in groups 2 and 3 (received 0.162 and 0.324 g/L Bensulfuron-methyl) compared to group 1, while a significant decrease was observed in group 4 (received 0.486 g/L Bensulfuron-methyl) compared to other groups. The number of red blood cells, the amount of hemoglobin, and the percentage of hematocrit in groups 3 and 4 showed a significant decrease compared to other groups, and the values of mean corpuscular volume, mean corpuscular hemoglobin, and mean corpuscular hemoglobin concentration were not significantly different in any groups. The amount of total serum protein in groups 3 and 4 decreased significantly compared to the control group. Serum glucose showed a significant increase in groups 3 and 4 compared to other groups. The values for aspartate aminotransferase, alanine transaminase, and alkaline phosphatase enzymes showed an increasing trend with the increase of Bensulfuron-methyl concentration. The most liver tissue damage was observed in group 4, which included hyperemia, hepatocyte vacuolar degeneration, edematous cell infiltration, bile duct hyperplasia, and hepatic necrosis.CONCLUSIONS: The increase in the concentration of Bensulfuron-methyl can cause liver tissue damage and changes in hematological and serum biochemical markers in common carp.

BACKGROUND: Tobacco (Nicotiana tobaccum) is a plant with piscicidal and fertilizing properties. OBJECTIVES: In this study the effect of different concentrations (0.1, 1, 10 and 100mg/l) of hydro-alcoholic extracts of tobacco has been examined on different tissues of Rainbow trout. METHODS: Samples from liver, kidney and gill of Rainbow trout were stained with hematoxylin and eosin and studied under light microscopy. RESULTS: Various histopathological lesions were observed in the liver of Rainbow trout exposed to different concentrations of tobacco. The results showed that with increase in concentrations of tobacco up to 10 and 100mg/l, bloodshed increased and hepatocytes lost their continuity and showed discontinuity mood. Lamellar aneurysm, bleeding and leukocytes infiltration, clubbing at the end of the lamellae, hyperplasia of secondary lamellar epithelium, epithelial lifting of secondary lamellae and creating an edematous space, lamellar shortening, vacuolation and lamellar fusion were the more abundant branchial lesions after exposure to tobacco. Separating the epithelium from basement membrane, hypertrophy, glomerular capillary dilation and tubular degeneration were observed in renal tissues in all treatments. At higher concentrations of tobacco (10 and 100mg/l), renal tubular necrosis was also observed. According to the results liver of rainbow trout showed a few histopathological alteration following exposure to tobacco extracts. Unlike the liver, gills of rainbow trout due to direct contact with pollutants showed more lesions. CONCLUSIONS: Tobacco extract has more pathological effects on gills in comparison with liver and kidney of Rainbow trout due to direct contact with the dissolved pollutant.