Diazinon (DZN) is a widely used pesticide that can affect the vital organs of non-target aquatic animals—mainly fish. This study evaluated the acute toxicity (LC₅₀) of six DZN concentrations (0.5, 0.75, 1.5, 2, 2.5, and 3 mg·L⁻¹) and, based on its evaluation after 24 h, 48 h, 72 h, and 96 h, two sublethal concentrations for chronic toxicity testing (0.01 and 0.05 mg·L⁻¹) for 21 days of exposure to DZN on grass carp fingerlings (Ctenopharyngodon idella Valenciennes, 1844). The median lethal concentrations of DZN at 24, 48, 72, and 96 h were 1.83, 1.57, 1.35, and 1.12 mg·L⁻¹, respectively. Next, histological observations after 96 h LC₅₀ showed oedema of the primary lamellae of the gills at low pesticide concentrations (0.5 to 1 mg·L⁻¹) and extensive necrosis of primary lamellae of the gills at higher concentrations (1.5 to 3 mg·L⁻¹). Moreover, cytoplasmic vacuolation and extensive necrosis were observed in liver tissue. Increased skin mucus, unbalanced swimming on the water surface, and increased gill opercula movements were noted during chronic exposure. Haematological parameters such as haematocrit, red blood cell count, white blood cell count, haemoglobin, and mean corpuscular volume were significantly reduced after 21 days of exposure to 0.05 mg·L⁻¹ of DNZ (p < 0.05). The present study shows that DZN has various toxic effects on grass carp, which may pose a potential risk for other fish species.

The increasing use of nano-based products raises concerns regarding potential risks related to their manufacturing, transportation, waste disposal, and management operations. We used the riverine carp, Capoeta capoeta, as an aquatic animal model to demonstrate the acute toxicity of silver nanoparticles (Ag-NPs). This study focuses on acute toxicity first, and then integrates the findings through histopathology, hematological, and biochemical testing of lethal and sub-lethal Ag-NPs exposures. Red blood corpuscles (RBC), white blood corpuscles (WBC), hematocrit, and total serum glucose levels were significantly lower in Ag-NPs-exposed fish than in control fish. Total serum protein, triglycerides, cholesterol, and albumin were all significantly greater in exposed fish. This research focused on the impacts of Ag-NPs on gills and liver tissue, and it was found that the level of injury escalated as the concentration of Ag NPs increased. Epithelial lifting of secondary lamellas (ELSL), epithelial hypertrophy (EH) of secondary lamellae (SL), leukocyte infiltration (LI), and bottom hyperplasia (BH) were all detected in Ag-NPs-exposed fish. In Ag-NPs-treated liver cross-sections of Capoeta capoeta, macrophage aggregates (MA), fatty liver (FL), sinusoid dilatation (SD), and necrosis (N) were identified. Ag-NPs dosages, according to biomarker representations, elicit stress-specific biochemical and physiological effects, compromising the general overall health status of aquatic animals. The gradients of toxic responses across exposure concentrations and portrayals of disrupted fish health with increasing silver nanoparticle exposure time indicate a reduced physiological ability for surviving in the wild.

The presence of pesticides and their potential toxic effects on fish can pose a threat to aquatic ecosystems and human health. The present study aimed to evaluate the effect of commercial formulations of glyphosate (Roundup) on the survival rate, hematological parameters, and tissues (gills and liver) of juvenile grass carp (Ctenopharyngodon idella). For these purposes, we exposed the fish to 0, 50, 100, and 150 mL L⁻¹ of Roundup for 96 hr. Results showed a significant correlation between the fish’s mortality rate and pesticide concentrations ( ); the LC₅₀ 96 hr of Roundup was 75.838 mL L⁻¹ in the present study. The concentrations above 50 mL L⁻¹ induced significant tissue lesions seen as lamellar aneurism, leukocyte infiltration, distal hyperplasia, cloudy swelling, macrophage aggregates, and necrosis in the gills and liver. We also reported a significant correlation between the severity of tissue damage and Roundup concentration. The hematocrit, hemoglobin, white, and red blood cell count significantly reduced after 96 hr of exposure to 100 and 150 mL L⁻¹. The opposite trend was reported for concentrations of glucose, albumin, cholesterol, total protein, and triglycerides. Finally, the fish exposed to 100 and 150 mL L⁻¹ of Roundup displayed some clinical signs, such as increasing operculum movement, darkening the skin, and swimming near the surface during the movement test. Overall, our results showed that concentrations of Roundup higher than 50 mL L⁻¹ can induce various toxic effects and significantly reduce the survival chance of juvenile grass carp. Roundup altered fish behavior, tissue functioning, and biochemical processes. In this study, we provided some basic knowledge about the effects of a glyphosate-based herbicide on aquatic organisms and possible environmental management.

Pesticides are usually used as an effective tool to control pests in agriculture; however, these chemicals may be a threat to nontarget organisms, especially aquatic organisms, because aquatic environments are the last station of pollutants. The present study evaluated the toxicity of a commercial formulation of neonicotinoid (acetamiprid 20% SP) as a systematic pesticide on the survival, hematology, and histology of the grass carp (Ctenopharyngodon idella). For these purposes, 105 fingerlings of the grass carp with an average body weight of 30 ± 2 g were exposed to 0, 50, 100, 150, and 200 mg·L⁻¹ of acetamiprid for 96 h. According to the data, a clear mortality was observed as the concentration of acetamiprid elevated ( ). The LC50 96 h of acetamiprid was 121.146 mg·L⁻¹. The hematological parameters in fish changed, following exposure to acetamiprid ( ). Also, a strong correlation was found between acetamiprid concentrations and stress bioindicators such as glucose, total protein, albumin, and cholesterol ( ). There was not significant tissue damage in the control group (0 mg·L⁻¹ of acetamiprid); however, acetamiprid led to tissues lesions such as hypertrophy, hyperplasia, uplifting of gill filaments, necrosis of gill epithelial cells, pyknosis and karyorrhexis of liver cells, and hemorrhage and necrosis of liver cell. Finally, acetamiprid-exposed fish exhibited some clinical signs including unbalanced swimming near the water surface, increasing operculum movement, and deaths with open-mouthed. The results of the present study clearly showed the survival-reducing effects of acetamiprid in C. Idella, which may return to tissue damage and stress induced by the pesticide. The results of the present study can be used as a base for future studies and environmental management.