The bioaccumulation of trace elements and heavy metals in aquatic organisms is a critical environmental concern due to its potential impact on ecosystem health and human safety. This study investigated the level of trace elements and heavy metals bioaccumulation in Labeo rohita and Mystus seenghala from the River Jhelum in the district Khushab, Punjab, Pakistan. The concentration of calcium, magnesium, iron, nickel, copper, arsenic, cadmium, zinc, chromium, manganese, cobalt, and lead in the gills, liver, and muscle tissues of these fish was measured using inductively coupled plasma-mass spectrometry. Then, the extent of contamination and its possible health risks were assayed. Our findings indicate significant variations in the elemental and metal concentrations among different organs and between species, reflecting their diverse feeding habits and habitats. The health risk assessment based on the estimated daily intake, estimated weekly intake, maximum permissible intake, target hazard quotient, hazard index or total target hazard quotient, health risk index, and target cancer risk revealed potential risks to human consumers of these fish. This study emphasizes the need for continuous monitoring, as new data and insights are crucial for understanding and mitigating these risks. Strict regulatory measures are also necessary to safeguard public health and preserve the ecosystem of Jhelum River.

Heavy metals enter river basins through industrial effluents, agricultural wastes, surface run-offs, and other human activities, negatively impacting aquatic and terrestrial life by bioaccumulating in the food chain. This problem is on a continuous rise in under-developed and developing countries, such as in Pakistan. Therefore, the current study was aimed to determine concentrations of heavy metals, essential trace elements, and macrominerals (Zn, Pb, Ni, Mn, Mg, Fe, Cu, Cr, Co, Cd, Ca, and As) in the water, sediments, and tissues (gills, liver, and muscles) of Bagarius bagarius and Bagre marinus in the Jhelum River, Pakistan. The hematological and biochemical profiles of these fish across two sampling sites (Jhelum Bridge Khushab, upstream, and Langarwala Pull—downstream) were also evaluated. Results showed greater bioaccumulation of heavy metals in fish downstream, correlating with higher concentrations of these metals in water and sediments downstream. In the case of B. marinus, the highest concentration observed was 16.59 mg/g (Ca), and the lowest concentration was 9.51 mg/g (Fe). In the case of B. bagarius, the highest concentration observed was 17.47 mg/g (Ca), and the lowest concentration was 7.95 mg/g (Mg). Increased activities of alkaline phosphatase (ALP), alanine aminotransferase (ALT), aspartate aminotransferase (AST), and lactate dehydrogenase (LDH) were observed downstream. Hematological changes included increased white blood cells (WBCs) and decreased red blood cells (RBCs), lymphocytes, hemoglobin (Hb), platelets (Plt), and hematocrit (Hct). A significant correlation was observed among heavy metals across the water, sediment, and different tissues of B. marinus and B. bagarius. Moreover, principal component analysis (PCA) for both species along both sampling sites illustrated the relationship between fish tissues and metals. The current study concluded that the fish accumulated a significantly higher concentration of heavy metals downstream, which might be linked with dumping of the domestic wastes and industrial and agricultural runoff, adversely affecting both fish and human health.

The continuous increase in the concentration of heavy metals in bodies of water due to human activity poses a serious threat to the sustainability and overall health of the ecosystem. This study investigated the essential and toxic elements bioaccumulation in various tissues (gills, muscles, liver, and brain) of the Minor carp (Labeo gonius) from two sampling sites of highly polluted Khushab Lake, a tributary of River Jhelum (in the Pakistan's Punjab province), along with a less exposed reference site (Chashma Lake-less polluted site). The impacts of pollution on the health profile of the fish were assessed using multiple biomarkers for analysis. The maximum accumulation of essential and toxic elements was reported in liver tissues, followed by gills. Copper (Cu) and iron (Fe) were the highest accumulated essential elements in liver and gills tissues, while magnesium (Mg) and calcium (Ca) were the highest accumulated in muscles and brain tissues. Hematological and serum biochemical profile of L. gonius showed intense abnormalities at Khushab Lake as compared to reference site. Histopathological investigations indicated severe alterations in the liver tissues along with significant changes in other tissues. Principal component analysis (PCA) showed strong correlations among essential and toxic elements in various tissues of fish. The results revealed that aquatic life in Lake Khushab is at the greatest risk to its health. Therefore, mitigating measures should be adapted by key stakeholders including environmental protection agency (ensure disposal of pre-treated wastes and effluents) and fisheries department (limnological assessment and stocking of fish at regular intervals).

A surge has been observed in the use of pesticides to boost agricultural yield in order to feed the continuously increasing human population. Different types and classes of broad-spectrum insecticides are in use, and the number is constantly increasing with the introduction of new ones. Keeping in view the broad-spectrum effects of organophosphate pesticides including Malathion (MLN), their use is continuously increasing without appraising their toxic impacts on non-target organisms. The continuous rise in the use of MLN has led to its presence, persistence, and transport to water bodies globally, subsequently affecting commercially valuable aquatic organisms. The current study was conducted to assess MLN-induced hematological and biochemical toxicities in the brain of a commercially valuable indigenous major carp, rohu, Labeo rohita. The fish was exposed to an acute concentration of commercial-grade MLN. The LC₅₀ of MLN (5 µg/L) led to behavioral inconsistencies and subtle impacts on the hematology (an increase in white blood cells and a reduction in red blood cells, hemoglobin, packed cell volume level, and mean corpuscular hemoglobin concentration) and biochemistry (an increase in reactive oxygen species, lipid peroxidation, activities of antioxidant enzymes (catalase, peroxidase, superoxide dismutase, glutathione, glutathione reductase, glutathione peroxidase, and glutathione-S-transferase) but a reduction in total protein content and activity of Na⁺/K⁺ ATPases) in the brain tissues. MLN also inhibited the activity of Acetylcholinesterase, while it led to an increase in Acetylcholine. Significant changes were observed in the serum biochemical profile; for example, glucose, cholesterol, potassium, urea, and total bilirubin increased, whereas total protein, sodium, chloride, albumin, and inorganic phosphate decreased after exposure. The current study clearly classified MLN as highly toxic to rohu. Therefore, the extra-judicious use of MLN should be strictly supervised. Studies concerning the real-world concentration of pesticides should be carried out on regular basis to mitigate the echoing issue of pesticide-based pollution.