Detailed Explanation of Common Pond-Clearing Drugs and Their Effects

Drug-based pond clearing is the use of drugs to kill various predatory fish, wild trash fish and other harmful organisms in the pond that endanger fish, shrimp and crab fry, creating a safe environmental condition for fry rearing. This is an important measure for improving the survival rate of fish, shrimp and crab fry. The commonly used pond-clearing drugs and their effects are introduced as follows:

1. Quicklime pond clearing and its effects: The action of quicklime in pond clearing is that after quicklime meets water, a chemical reaction occurs, producing calcium hydroxide and releasing a large amount of heat. Calcium hydroxide is a strong base, and its hydroxide ions can raise the pH value of the pond water to above 11 in a short time, thereby killing wild trash fish and other harmful organisms.

Pond-clearing methods and effects: ① Dry pond clearing: after the pond water is drained, leave about 10cm of water, and use 60-75 kg of quicklime per mu; for ponds with less silt, use 50-60 kg. ② Clearing with water retained: for ponds where the water is not drained, the quicklime dosage is 125-150 kg per mu at an average water depth of 1 m. It can kill wild trash fish, frog eggs, tadpoles, shrimp, crabs, aquatic insects, parasites, pathogenic bacteria and some aquatic plants with shallow roots and soft stems; maintain the pond water slightly alkaline; and increase water fertility, etc.