Specimens of Heteropneustes fossilis were treated with various levels of malathion and its 96 h LC₅₀ value was determined. The effects of sub-lethal concentrations of insecticide on hematological and biochemical profile of Heteropneustes fossilis were also registered. The 96 h LC₅₀ value obtained was 8.81 mg/l. Exposure of sub-lethal doses (0.44, 0.88 and 1.76 mg/l which are 5, 10 and 20% of the LC₅₀) of malathion to Heteropneustes fossilis for 3 weeks demonstrated that the toxicant had a detrimental effect on the blood profile of fish. Blood cell (Erythrocyte and leucocytes) counts (from 1.66 to 1.44 cell × 10⁶ × mm³ and 37.93 to 30.24 cell × 10³ × mm³; respectively), haemoglobin (Hb) level (from 6.21 to 3.54 g/dl) and haematocrit (Ht) estimates (from 34.26 to 30.52%) were reduced in the fishes exposed to malathion. Elevated level (from 46.25 to 92.45 mg/100 ml) of glucose and decreased quantity (29.95 to 24.25 g/dl) of protein in plasma was registered. Glycogen content in muscle and liver was also decreased. The activity of enzymes glutamic-oxaloacetic transaminase (GOT) and glutamic-pyruvic transaminase (GPT) were high in the fish treated with pesticide. The possible causes for variations in the different parameters were identified and discussed.

用不同水平的马拉硫磷处理化石异化菌的标本，并测定其96 h LC ₅₀值。还记录了亚致死浓度的杀虫剂对化石异形螨血液学和生化特性的影响。获得的96 h LC ₅₀值为8.81 mg / l。将马拉硫磷的亚致死剂量（0.44、0.88和1.76 mg / l，分别为LC _50的5、10和20％）暴露于化石异形藻3周，证明该毒物对鱼类的血液状况有不利影响。血细胞（红细胞和白细胞）计数（从1.66到1.44细胞×10 ⁶  ×mm ³和37.93至30.24格×10 ³  ×mm ³ ; 暴露于马拉硫磷的鱼的血红蛋白（Hb）水平（从6.21至3.54 g / dl）和血细胞比容（Ht）估计值（从34.26至30.52％）降低。记录血浆中葡萄糖水平升高（从46.25到92.45 mg / 100 ml）和蛋白减少量（29.95到24.25 g / dl）。肌肉和肝脏中的糖原含量也降低了。农药处理过的鱼中谷氨酸-草酰乙酸转氨酶（GOT）和谷氨酸-丙酮酸转氨酶（GPT）的活性较高。确定并讨论了不同参数变化的可能原因。