The acute toxicity of povidone iodine, trichloroisocyanuric acid, and lambda-cyhalothrin on Cyprinus carpio Songhe [(118.8±5.63) cm in length, (72.75±15.11) g in body mass]was investigated at a water temperature of (20±1) ℃ using a static bioassay method. The results revealed that the median lethal concentration (LC₅₀) of povidone iodine was 870.551 mg/L at 24 h, 790.650 mg/L at 48 h, 694.959 mg/L at 72 h, and 654.692 mg/L at 96 h, with a safe concentration of 195.653 mg/L. For trichloroisocyanuric acid, the LC₅₀ was 23.076 mg/L at 24 h, 19.608 mg/L at 48 h, 15.674 mg/L at 72 h, and 13.871 mg/L at 96 h, with a safe concentration of 4.247 mg/L. The LC₅₀ of lambda-cyhalothrin was 4.620 mg/L at 24 h, 2.216 mg/L at 48 h, 1.205 mg/L at 72 h, and 0.847 mg/L at 96 h, with a safe concentration of 0.153 mg/L. The descending order of toxicity among the three substances to C.carpio Songhe was lambda-cyhalothrin > trichloroisocyanuric acid > povidone iodine. Based on toxicity evaluation criteria, povidone iodine and trichloroisocyanuric acid exhibited low toxicity for C.carpio Songhe and could be considered as the preferred choices in practical applications. However, lambda-cyhalothrin demonstrated high toxicity for C.carpio Songhe, requiring careful consideration and cautious use in practice.

The Yellow River carp(Cyprinus carpio haematoperus)is one of the most important commercial fish species in the Yellow River Basin of China.The Yellow River carp,Songjiang perch(Trachidermus fasciatus),Xingkai Lake culter(Culterinae)and Songhua River salmon(Oncorhynchus keta)are collectively known as the four famous freshwater fish in China.In recent years,due to disorderly fishing,the wild resources of the Yellow River carp have declined sharply.Scientifically formulating the fishing strategy of the Yellow River carp has important practical significance for the sustainable utilization of the Yellow River carp resources.In order to formulate the Yellow River carp catchable size and total allowable catch in the Yellow River of Henan Province,on basis of investigative data,by analyzing the length - weight formula,body length and weight growth equation,and instantaneous mortality rate,we calculated the weight growth inflexion age,the critical age and the biomass of the Yellow River carp in the Yellow River of Henan Province.The result indicated that the growth equation of length and weight were L_t=625×(1-e^{-0.31(t+0.387)})and W_t=5 343.3×(1-e^{-0.31(t+0.387)}) ^3.014,respectively.The weight growth inflection age and critical age of the Yellow River carp were 3.17 and 3.73 age,respectively.The biomass in the Yellow River of Henan Province was about 70 852.13 t.To the Yellow River carp stock in the Yellow River of Henan Province,the catchable length was about 417.6~450.6 mm,and catchable weight was about 1 584.9~1 993.2 g.Total allowable catch was about 24 801.06 t.