Pesticides such as endosulfan, heptachlor and dieldrin persist in aquatic environments as a result of their resistance to biodegradation. However, there is no adequate information about the toxicity of endosulfan, heptachlor and dieldrin to the aquatic organism, African catfish (Clarias gariepinus)—a high valued widely distributed commercially interesting species. The current experiment was performed with the aim to determine the median lethal concentration (LC₅₀) of endosulfan, heptachlor and dieldrin to African catfish (Clarias gariepinus); their behavioral abnormalities and histopathological alterations in several vital organs. A total of 324 juvenile fish were exposed for 96 h to six concentrations of endosulfan and dieldrin at 0, 0.001, 0.002, 0.004, 0.008 and 0.016 ppm, and to heptachlor at concentrations of 0, 0.02, 0.04, 0.08, 0.16 and 0.32 ppm for dose-response tests. The study demonstrated that the species is highly susceptible to those contaminants showing a number of behavioral abnormalities and histopathological changes in gill, liver and muscle. The 96-h LC₅₀ value of endosulfan, dieldrin and heptachlor for the African catfish was found as 0.004 (0.001−0.01) mg/L, 0.006 mg/L and 0.056 (0.006−0.144) mg/L, respectively. Abnormal behaviors such as erratic jerky swimming, frequent surfacing movement with gulping of air, secretion of mucus on the body and gills were observed in response to the increasing exposure concentrations. Histopathological alterations of liver, gill and muscle tissues were demonstrated as vacuolization in hepatocytes, congestion of red blood cells (RBCs) in hepatic portal vein; deformed secondary lamellae and disintegrated myotomes with disintegrated epidermis, respectively. These findings are important to monitor and responsibly manage pesticide use in and around C. gariepinus aquacultural areas.

Substantial quantities of pesticides are routinely applied to enhance agricultural crop production. Pesticides used in this way continuously accumulate in the environment and in foods. Harvested crops contain pesticide residues at various concentrations, with potential harmful impacts on human health. Hence, it is of value to identify techniques for the effective decontamination of tainted foods. However, cleaning with water or household agents, e.g., acetic acid and sodium bicarbonate, are recognized treatments for the efficient degradation of pesticides from vegetables and fruits. There is an apparent void of information about the decontamination treatments for raw fishes using household agents that are affordable for all classes of consumers. Hence, the present study was performed to determine the most efficient household technique for reducing pesticide residue levels from precooked raw fish to ensure the utmost food safety. Fish muscles of four species of fishes, viz., Clarias gariepinus, Channa striatus, Anabas testudineus and Trichogaster trichopterus, were treated with six treatments: washing with running tap water (T₁), dipping in normal water (T₂), dipping in 2% salt solution (T₃), dipping in 2% vinegar (T₄), dipping in 0.1% sodium bicarbonate solution (T₅) as well as dipping in 0.1% sodium bicarbonate solution + 2% vinegar + 2% salt solution + lemon juice (T₆), as fish muscle is the major consumable portion of fish. The current study demonstrated that the removal percentage of lindane, heptachlor, aldrin, endosulfan, dieldrin, endrin, DDT, methoxychlor and cypermethrin residues against the treated household treatments, in downward order, were soaking in 0.1% sodium bicarbonate solution + 2% vinegar + 2% salt solution + lemon juice solution (T₆) > soaking in 2% vinegar (T₄) solution > soaking in 0.1% sodium bicarbonate (T₅) solution > soaking in 2% salt (T₃) solution > washing with running tap water (T₁) > soaking in stable normal water (T₂). The treatment of raw fish muscle samples by soaking them in 0.1% sodium bicarbonate solution + 2% vinegar + 2% salt solution + lemon juice was found to be the most efficient household treatment, performing significant reductions (%) in pesticide concentration: 72–80% (p < 0.05) in Channa striata, 71–79% (p < 0.05) in Clarias gariepinus, 74–80% (p < 0.05) in Anabas testudineus as well as 78–81% (p < 0.05) in Trichogaster trichopterus before cooking.

The current study was carried out to examine the effects of four different experimental salinities (T ₁ = 0‰, T ₂ = 5‰, T ₃ = 10‰, and T ₄ = 15‰) on growth, water quality, proximate composition, total bacterial (TB), and hemocyte counts of white leg shrimp ( Litopenaeus vannamei ) and giant prawn ( Macrobrachium rosenbergii ) in biofloc based nursery bi‐culture system for 6 weeks. A total of 12 cylindrical plastic tanks (125 L) filled up 100 L water for rearing L. vannamei and M. rosenbergii post‐larvae (PLs) at an equal ratio: (50 L. vannamei : 50 M. rosenbergii ). At the end of the experiment, for L. vannamei , the significantly higher ( p < 0.05) growth rate was recorded in T ₄ (15‰) compared to the other treatments. For M. rosenbergii , a significantly higher ( p < 0.05) growth rate was recorded in T ₂ (5‰) than in other treatments. Similar to growth, the best ( p < 0.05) feed conversion ratio (FCR) for ‐ L. vannamei was found at T ₄ (15‰) while it was at T ₂ (5‰) for M. rosenbergii . Gross return, net profit, and benefit–cost ratio (BCR) analysis revealed higher profit T ₄ (15‰) than T ₃ (10‰), T ₂ (5‰), and T ₁ (0‰). TB counts were found to be significantly greater ( p < 0.05) in T ₄ than other treatments. Hemocyte counts for L. vannamei were significantly higher ( p < 0.05) in T ₄ (15‰) than T ₃ (10‰), T ₂ (5‰), and T ₁ (0‰) and for M. rosenbergii hemocyte was significantly higher ( p < 0.05) in T ₁ (0‰) than T ₂ (5 ‰), T ₃ (10 ‰), and T ₄ (15‰). Therefore, it can be suggested that 15‰ salinity will be the best condition for the nursery bi‐culture of white leg shrimp ( L. vannamei ) and giant prawn ( M. rosenbergii ) in the biofloc system.

Cadmium is a trace element which is not essential for human being. High cadmium concentration in some rice samples in Bangladesh was reported than that of other countries. This study was carried out to find out the Cd concentration fertilizers, soils, rice and vegetables and along with other chemical properties of Karotia union, Tangail sadar upazila, Tangail. A total of 29 samples were collected among the 14 soils from 7 stations at 0-15 cm and 16-30 cm depth respectively, 5 vegetables, 5 rice and also 4 different countries TSP fertilizers from local market. The Cd concentration values of all soil samples were found between 0.97 to 1.73 mg/kg (0-15 cm) and 0.53 to 0.83 mg/kg (16-30 cm), respectively and the vegetable sample values were found between 0.053 mg/kg to 0.123 mg/kg (d.w.).The rice sample values were found between 0.05 mg/kg to 0.096 mg/kg (d.w.). The fertilizer sample values were found between 20.67 to 92.33 mg/kg. The soil pH values obtained 7.06 to 7.70 (0-15 cm) and 7.48 to 7.88 (16-30 cm) which indicated that the study area soils were neutral to moderately alkaline. The EC values of all soil samples were between 47.67 to 82.67dSm-1 (0-15cm) and 33.33 to 58.33dSm-1 (16-30 cm). The organic matter content of all soils ranged from 0.789 to 0.905% and 0.351 to 0.869% at (0-15 cm and 16-30 cm), respectively. The available sodium (Na) values of soils were found between 1.84 to 1.92 ppm (0-15 cm) and 1.83 to 1.90 ppm (16-30 cm), respectively. The available potassium values ranged from 1.81 to 1.96 ppm (0-15 cm) and 1.84 to 1.97 ppm (16-30cm), respectively. The available calcium values of all soil samples were 1.92 to 1.97 ppm (0-15 cm) and 1.91 to 1.96 ppm (16-30 cm), respectively.