CATDOLL : CATDOLL: How to prevent and eliminate moss in shrimp ponds?

As the water temperature rises in spring, moss begins to sprout in the shallow water of the pond, grows into strands of green, floats on the water, and forms tangled clumps of filaments. Shrimp fry and young shrimp often swim into the moss and get entangled and die. The main methods to prevent and eliminate moss in shrimp ponds are:

(1) After the pond is thoroughly cleaned, the water quality should be fertilized immediately to prevent the appearance of moss. The water depth should be 50 cm in the early stage and gradually increased to 1.2 m in the later stage. The transparency should be 30-35 cm. If moss appears, measures should be taken as soon as possible. Local drugs can be used to kill it. Manual fishing often leads to more moss.

(2) Use copper sulfate or moss cleaner to kill moss: Generally, use 0.7 grams of copper sulfate per cubic meter of water. Change the water appropriately after 20 hours of application. Moss cleaner is better than watering after mixing with soil and spreading dry. After the moss is killed, apply fermented organic fertilizer in time. The amount is generally 100-150 kg/mu. Apply topdressing appropriately according to the changes in water quality. Keep the water body always fertile to prevent the resurgence of moss.

(3) Urea also has a killing effect on moss. It can be directly sprinkled on the moss and then sprinkled again after 3 to 5 days.

(4) Spread wood ash at a rate of 20-30 kg/mu.

(5) Applying Masson pine leaf slurry: Use 10 kg of fresh Masson pine leaves per acre of water surface, soak and grind them, add water to make 25 kg of slurry, and sprinkle it all over the pond once a day. Continue to tame it by hand for 2 to 3 days.

Appendix Appendix 1 Pollution-free food freshwater shrimp (NY 5158-2005)

1 Scope This standard specifies the requirements, test methods, inspection rules, marking, packaging, transportation and storage of pollution-free freshwater shrimp.

This standard is applicable to live and fresh products of Macrobrachium rosenbergii, Macrobrachium nipponensis, Penaeus vannammi and Procambarus clarkii. Other freshwater shrimps may refer to this standard for implementation.

2 Normative References The clauses in the following documents become the clauses of this standard through reference in this standard. For all referenced documents with dates, all subsequent amendments (excluding errata) or revisions are not applicable to this standard. However, parties that reach an agreement based on this standard are encouraged to study whether the latest versions of these documents can be used. For all referenced documents without dates, the latest versions are applicable to this standard.

GB/T5009.11 Determination of total arsenic and inorganic arsenic in foods GB/T5009.12 Determination of lead in foods GB/T5009.15 Determination of cadmium in foods GB/T5009.17 Determination of total and inorganic mercury in foods NY5051 Quality of water for freshwater aquaculture of pollution-free foods SC/T3015 Determination of oxytetracycline, tetracycline and chlortetracycline residues in aquatic products SC/T3016-2004 Sampling methods for aquatic products 3 Requirements 3.1 Sensory requirements 3.1.1 Live shrimps Live shrimps have their normal body color and luster, are well-proportioned, have normal shape, are agile and free from disease.

3.1.2 Fresh shrimps Fresh shrimps shall meet the requirements of Table 1.

Table 1 Sensory requirements Item Requirements Morphology The shrimp body is intact, and the connecting membrane should not be broken in more than one place. The shrimp body has a bright appearance, and the shell is shiny. The shrimp head should not have black spots or black circles. Odor The odor is normal, without odor. Muscle tissue is tight and elastic. Boiling test After boiling, it has the inherent umami flavor of shrimp, and the taste of muscle tissue is tight and elastic. Note: When the morphology, odor, and muscle tissue cannot determine the product quality, the boiling test is carried out. 3.2 Safety indicators The safety indicators should meet the requirements of Table 2.

Table 2 Safety indicators Item Indicator Mercury (in Hg), mg/kg ≤0.5 Arsenic (in As), mg/kg ≤0.5

Table 2 Safety indicators (continued) -1 Item Indicator Lead (measured in Pb), mg/kg ≤0.5 Cadmium (measured in Cd), mg/kg ≤0.5 Oxytetracycline, mg/kg ≤100 Note: Other pesticides and veterinary drugs shall comply with relevant national regulations 4 Test method 4.1 Sensory test 4.1.1 In a well-lit and odor-free environment, place the sample on a white enamel tray or on a stainless steel workbench and inspect each item according to the requirements of Article 3.1.

4.1.2 Boiling test: Add 500mL of drinking water to a container that does not produce any odor. After the water is boiled, take about 100g of the sample, wash it with clean water, put it in a container, cover it, boil it for 5 minutes, open the lid, smell the odor, and then taste the meat. 4.2 The determination of total mercury shall be carried out in accordance with the provisions of GB/T5009.17. 4.3 The determination of total arsenic shall be carried out in accordance with the provisions of GB/T5009.11. 4.4 The determination of lead shall be carried out in accordance with the provisions of GB/T5009.12. 4.5 The determination of cadmium shall be carried out in accordance with the provisions of GB/T5009.15. 4.6 The determination of oxytetracycline shall be carried out in accordance with the provisions of SC/T3015.

5 Inspection rules 5.1 Batch rules and sampling methods 5.1.1 Batch rules Live shrimps produced in the same shrimp pond or farm under the same conditions are considered as one inspection batch; fresh shrimps produced from the same source and size are considered as one inspection batch.

5.1.2 The sampling method shall be in accordance with the provisions of SC/T3016.

5.1.3 Sample preparation shall be carried out in accordance with the provisions of Appendix C of SC/T3016. 5.2 Inspection classification Products are divided into factory (field) inspection and type inspection.

5.2.1 Factory Inspection Each batch of products shall be subject to factory (field) inspection. The factory (field) aging inspection shall be carried out by the producer and the inspection items shall be sensory indicators.

5.2.2 Type inspection Type inspection should be carried out when any of the following situations occurs, and the inspection items shall be all the items specified in this standard.

a) Shrimp cultured in newly built farms; b) When the culture conditions change and may affect the product quality; c) When the relevant administrative department requires type inspection; d) When there is a large difference between the outbound inspection and the last type inspection; e) During normal production, periodic inspection at least once a year. 5.3 Judgment rules 5.3.1 The sensory inspection items of live and fresh shrimps shall all comply with the provisions of Article 3.1; the results shall be determined in accordance with the provisions of Table 1 of SC/T3016.

5.3.2 If one or more of the safety indicators in the inspection results are unqualified, the batch of products will be judged as unqualified and shall not be re-inspected.

6 Marking, packaging, transportation and storage 6.1 Marking The product should indicate the name, place of origin, name and address of the manufacturer and date of production. 6.2 Packaging 6.2.1 Packaging materials Packaging materials should be strong, clean, non-toxic and free of odor.

6.2.2 Packaging requirements 6.2.2.1 Live shrimps should be packed with sufficient oxygen and the water quality should meet the requirements of NY5051.

6.2.2.2 Fresh shrimps should be placed in clean fish boxes or incubators to keep the shrimp body temperature between 0℃ and 4℃; avoid external damage to the shrimp body.

6.3 Transportation 6.3.1 During the transportation of live shrimp, sufficient oxygen must be provided.

6.3.2 Fresh shrimps should be transported by refrigerated or insulated vehicles or ships, keeping the shrimp body temperature between 0℃ and 4℃.

6.3.3 The means of transport should be clean, non-toxic and odorless to prevent transportation pollution. 6.4 Storage 6.4.1 Live shrimps should be stored with sufficient oxygen. The water used for temporary storage should comply with the provisions of NY5051.

6.4.2 When storing fresh shrimp, the temperature of the shrimp body should be kept between 0℃ and 4℃.

6.4.3 The storage environment should be clean, non-toxic, odorless, pollution-free and meet hygiene requirements.

Appendix 2 Technical Specifications for the Farming of Pollution-free Freshwater Shrimp (NY/T 5285-2004)

1 Scope This standard specifies the environmental conditions, seed propagation, seed cultivation, edible shrimp breeding and shrimp disease prevention and control techniques for pollution-free aquaculture of freshwater shrimp (scientific name: Macrobrachium nipponensis).

This standard is applicable to pollution-free shrimp pond farming, and can be used as a reference for rice field farming.

2 Normative References The clauses in the following documents become the clauses of this standard through reference in this standard. For all referenced documents with dates, all subsequent amendments (excluding errata) or revisions are not applicable to this standard. However, parties that reach an agreement based on this standard are encouraged to study whether the latest versions of these documents can be used. For all referenced documents without dates, the latest versions are applicable to this standard.

GB13078 Feed hygiene standard GB18407.4-2001 Agricultural product safety and quality Pollution-free aquatic product production environment NY5051 Pollution-free food freshwater aquaculture water quality NY 5071 Pollution-free food fishery drug use guidelines NY5072 Pollution-free food fishery compound feed safety limit SC/T1008 Conventional pond culture of fish fry and fingerling technical specifications "Aquaculture Quality and Safety Management Regulations" Ministry of Agriculture of the People's Republic of China Order (2003) No. [31] 3 Environmental conditions 3.1 Site selection Adequate water source, convenient irrigation and drainage, separate water inlet and outlet, and no pollution sources within 3km around the farm. 3.2 Water source and water quality The water quality should be fresh and should comply with the requirements of NY 5051, with the dissolved oxygen level above 5 mg/L and pH 7.0-8.5. 3.3 Shrimp pond conditions The shrimp pond is rectangular, east-west oriented, with loam or clay soil. The main conditions are shown in Table 1; and there are complete and independent water inlet and drainage systems.

Table 1 Shrimp pond conditions Pond type Area (m2) Water depth (m) Inner slope of pond bank Ratio of aquatic plants planting area (m2) Freshwater shrimp breeding pond 1 000-3 000 About 1.5 1:3-4 1/5-1/3 Seedling breeding pond 1 000-3 000 1.0-1.5 Edible shrimp breeding pond 2 000-6 700 About 1.5 1:3-4 1/5-1/3 3.4 Bottom quality of shrimp pond The bottom of the shrimp pond is flat, with silt less than 15 cm. The bottom quality meets the requirements of 3.3 of GB 18407.4-2001.

4 Seedling propagation 4.1 Source of broodstock Wild freshwater shrimps caught from rivers, lakes, ditches and other waters with good water quality should be selected as broodstock. They should be disease-free, healthy, larger than 4 cm in size and sexually mature. Alternatively, freshwater shrimps larger than 5 cm in size with eggs can be purchased directly as broodstock during the breeding season. Broodstock should be quarantined before breeding.

4.2 Stocking density: 45kg to 60kg of broodstock per 1 000m2, with a female to male ratio of 3 to 4:1.

4.3 Feed and feeding Broodstock feed is mainly compound feed, and the feeding amount is 2% to 5% of the body weight of broodstock. The safety limit of feed should comply with the provisions of NY5072, and high-quality non-toxic, harmless and pollution-free fresh animal feed should be appropriately added, and the feeding amount is 5% to 10% of the body weight of broodstock.

4.4 Spawning by Broodstock When the water temperature rises to above 18℃, broodstock begin to mate and lay eggs. The shrimps carrying eggs are caught with ground cages and then cultivated and hatched in seedling cultivation ponds. You can also purchase wild shrimps carrying eggs and move them into seedling cultivation ponds for cultivation and hatching.

4.5 Hatching of brooding shrimps The stocking rate of brooding shrimps is 12kg to 15kg per 1,000m2. According to the color of the shrimp eggs, brooding shrimps with similar embryonic development periods are selected and placed in the same pond for hatching. During the shrimp hatching process, water should be flushed every day to keep the water fresh. Generally, it takes 20d to 25d for the shrimp eggs to hatch. When the shrimp eggs become transparent and the embryos have eye spots, 150kg to 450kg of decomposed pollution-free organic fertilizer should be applied per 1,000m2. When more than 80% of the brooding shrimps have hatched into larvae, the parent shrimps are caught with ground traps.

5 Seedling cultivation 5.1 Larvae density The stocking density of larvae in pond cultivation should be controlled below 2,000/m2. 5.2 Feeding 5.2.1 In the first stage, when larvae are found in the hatching pond, soybean milk should be fed in time. The feeding amount is 2.5 kg of soybean milk per 1,000 m2 per day, and then gradually increased to 6.0 kg per day. Feeding method: Feed once every day at 8:00-9:00 and 16:00-17:00.

5.2.2 Three weeks after the second-stage larvae are hatched, gradually reduce the amount of soy milk fed and increase the amount of compound feed for freshwater shrimp seedlings. The safety limit of compound feed should comply with the provisions of NY 5072. After one week of feeding with compound feed, the daily feeding amount is 30kg/hm2 to 45kg/hm2, and the feeding time is 17:00 to 18:00 every day.

5.3 Fertilization After the larvae are hatched, decomposed organic fertilizers should be applied in time about 15 days, depending on the amount of plankton in the water and the feeding conditions of the larvae. The amount of fertilizer applied each time is 75kg to 150kg per 1,000m2.

5.4 Thinning When the juvenile shrimp grows to 0.8cm-1.0cm, they should be thinned in time according to the density of the culture pond. The density of juvenile shrimp culture should be controlled below 1,000 shrimp/m2. 5.5 Water quality requirements The water quality requirements of the culture pond are: transparency of about 30cm, pH7.5-8.5, dissolved oxygen ≥5mg/L.

5.6 Shrimp fry fishing After 20-30 days of cultivation, when the young shrimp grows larger than 1.0 cm, shrimp fry can be harvested and enter the edible shrimp farming stage. Shrimp fry fishing can be carried out by using dense nets, scooping nets or releasing water to collect fry.

6. Rearing of Edible Shrimp 6.1. Pond Conditions 6.1.1. Water Inlet Requirements The water inlet should be filtered using a filter bag made of sieve silk with a mesh size of 0.177mm to 0.250mm.

6.1.2 Supporting facilities Ponds mainly used for breeding freshwater shrimp should be equipped with mechanical equipment such as water pumps and aerators. Aeration equipment with a power of more than 4.5 kW should be installed per hectare of water surface.

6.2 Preparation before stocking 6.2.1 Pond cleaning and disinfection shall be carried out in accordance with the provisions of SC/T 1008.

6.2.2 Aquatic plant planting The area for aquatic plant planting shall comply with 4.2 of this standard. Aquatic plant species to be planted may include submerged plants such as Vallisneria, Hydrilla verticillata, Potamogeton oleifera and Elodea, as well as aquatic plants such as Water Peanut or Water Spinach (Water Spinach).

6.2.3 Water injection and fertilization 5 to 7 days before stocking shrimp fry, fill the pond with water to a depth of 50 to 60 cm; at the same time, apply 2,250 to 4,500 kg/hm2 of decomposed organic fertilizer to cultivate plankton.

6.3 Stocking of shrimp fry 6.3.1 Stocking method Stocking should be done on sunny days. Before stocking, take pond water to test the shrimp fry. When it is confirmed that the pond water has no adverse effect on the shrimp fry, formal stocking of shrimp fry can be started. The temperature difference during stocking of shrimp fry should be less than ±2℃. Water should be brought along when catching, transporting and stocking shrimp fry.

6.3.2 Culture mode and stocking density 6.3.2.1 The culture mode of stocking enough shrimp fry in a single season and catching the big ones and keeping the small ones all year round is adopted. Stocking density: 600,000 to 750,000 shrimp fry (about 2,000/kg) are stocked from January to March; or 900,000 to 1.2 million shrimp fry with a total length of 1.5 cm to 2 cm are stocked from July to August. 15 days after the shrimp fry are stocked, the mixed culture specifications in the pond are 1,500 to 3,000 silver carp and bighead carp with a body length of 15 cm or 22,500 silver carp and bighead carp in summer. The main tool for catching edible shrimp is ground trap fishing.

6.3.2.2 Multi-season aquaculture The Yangtze River Basin has two-season aquaculture, while the Pearl River Basin can have three-season aquaculture.

Stocking density: 2,000 shrimps/kg for wintering seedlings, 450,000 to 600,000 shrimps/hm2 for seedlings of 1.5 cm to 2 cm, 600,000 to 800,000 shrimps/hm2 for seedlings of 1.5 cm to 2 cm. Stocking time: generally from July to August and from December to March of the following year. 15 days after the seedlings are stocked, 1,500 to 3,000 silver carp and bighead carp of 15 cm or 22,500 silver carp and bighead carp of summer are mixed in the pond.

6.3.2.3 Fish and shrimp polyculture In edible fish ponds or fingerling ponds with a unit output of 7,500 kg/hm2 of non-carnivorous fish, fresh shrimps are cultured together. The general stocking rate of shrimp fry is 150,000 to 300,000 per hm2. The stocking rate of fresh shrimp fry can be appropriately increased in fingerling ponds, and the stocking time is generally in winter and spring.

6.3.2.4 The mixed culture stocking pattern and stocking quantity of shrimp, fish and crab are shown in Table 2.

Table 2 Stocking table of mixed culture of shrimp, fish and crab Variety Specification Stocking quantity Stocking time Fresh shrimp Total length 2cm～3cm 450,000/hm2 January～March River crab 100/kg～200/kg 4 500/hm2 January～March Mandarin fish Body length 5cm～10cm 225/hm2～300/hm2 July Bighead carp 0.5kg/tail～0.75kg/tail 150/hm2～225/hm2 January～March 6.4 Feeding management 6.4.1 Feed feeding The feed feeding should follow the "four fixed" feeding principle, and achieve fixed quality, fixed quantity, fixed location and fixed time.

6.4.1.1 Feed requirements It is recommended to use shrimp compound feed. Compound feed should be free of mold and deterioration, and free of pollution. Its safety limit requirements shall comply with the provisions of NY 5072. Single feed should be palatable, free of mold and deterioration, and free of pollution. Its hygiene indicators shall comply with the provisions of GB 13078. Fresh feed should be fresh, palatable, free of corruption and deterioration, non-toxic and non-polluting.

6.4.1.2 Feeding method: Feed twice a day, once at 8:00-9:00 and once at 18:00-19:00. The amount fed in the morning is 1/3 of the total daily feed amount, and the remaining 2/3 is fed in the evening. Feed is fed underwater 1.5m away from the edge of the pond, either at multiple points or in a line.

6.4.1.3 Feeding Amount The daily feeding amount of compound feed for each month during the shrimp rearing period is shown in Table 3. The actual feeding amount should be flexibly controlled in combination with weather, water quality, water temperature, feeding and molting conditions, and the feeding amount should be appropriately increased or decreased.

Table 3 Daily feeding rate of compound feed in each month during the shrimp rearing period Month 3 4 5 6 7 8 9 10 11 12 Daily feeding rate % 1.5～2 2～3 3～4 4～5 5 5 5 5～4 4～3 26.4.2 Water quality management 6.4.2.1 The transparency of the culture pond water should be controlled at 25cm～30cm in the early stage of culture (March～May), 30cm in the middle stage (June～July), and 30cm～35cm in the late stage (August～October). Dissolved oxygen should be maintained above 4mg/L. pH 7.0～8.5.

6.4.2.2 Fertilization and water adjustment Fertilizers should be applied in a timely manner according to the changes in the transparency of the aquaculture water quality. Generally, decomposed organic fertilizers should be applied once every 10 to 15 days in the early stage of aquaculture, and once every 15 to 20 days in the middle and late stages. The amount of fertilizer applied each time is 750 kg/hm2 to 1 500 kg/hm2.

6.4.2.3 Replacement of water with new water In the early stage of aquaculture, water is not replaced but new water is added once every 7 to 10 days, with 10 cm to 20 cm of water each time. In the middle stage, water is replaced once every 15 to 20 days. In the later stage, water is replaced once a week, with 15 cm to 20 cm of water each time.

6.4.2.4 Use of quicklime During the shrimp farming period, quicklime should be used once every 15 to 20 days, with the amount used each time being 150 kg/hm2. After it is turned into slurry, it should be evenly sprayed throughout the pond.

6.4.3 Daily Management 6.4.3.1 Patrol the ponds once in the morning and once in the evening every day to observe changes in water color, shrimp activities and feeding conditions; check whether there are any leaks in the pond foundation and whether the escape prevention facilities are intact.

6.4.3.2 During the aeration growth period, the aerator is generally turned on once in the early morning and at noon each day, each time for 1.0h to 2.0h; on rainy days or when the air pressure is low, the start time will be extended.

6.4.3.3 Growth and disease inspection Sampling should be carried out once every 7 to 10 days, with the number of samples exceeding 50, to inspect the growth and feeding conditions of the shrimps and to check for diseases, which will be used as the basis for adjusting the feeding amount and the use of drugs.

6.4.3.4 Records Aquaculture production records shall be kept in the format required by the Ministry of Agriculture of the People’s Republic of China Order (2003) No. [31] “Regulations on the Management of Quality and Safety of Aquaculture”.

7 Disease Control 7.1 Principles of Shrimp Disease Control In the process of pollution-free shrimp farming, the principle of prevention-oriented and comprehensive control shall be adhered to. The use of control drugs shall comply with the requirements of NY 5071, and have veterinary drug registration certificate, production approval certificate and execution approval number. And keep records of drug use in the format required by the Ministry of Agriculture of the People's Republic of China (2003) No. [31] "Regulations on the Quality and Safety Management of Aquaculture". 7.2 Prevention and Control of Common Shrimp Diseases Common diseases in shrimp farming are mainly red body disease, black gill disease, black spot disease, parasitic protozoan diseases, etc. Specific prevention and control methods are shown in Table 4.

Table 4 Treatment methods for common diseases of freshwater shrimp Shrimp disease name Symptoms Treatment methods Withdrawal period Precautions Red body disease The tail of freshwater shrimp turns red in the early stage of the disease, then spreads to the swimming legs and the entire abdomen, and finally the head, chest and walking legs turn red. Sick shrimps move sluggishly, lose appetite or stop eating, and in severe cases can cause large-scale death 1. Spray the entire pond with chlorine dioxide, dosage: 0.1mg/L~0.2mg/L, 0.3mg/L~0.6mg/L in severe cases 2. Mix sulfamethoxazole 100mg/kg body weight or florfenicol 10mg/kg body weight with bait and feed, use for 5d~7d, and double the dosage on the first day. For prevention, halve the dosage and continue for 3-5 days. 3. Spray the whole pond with povidone iodine (juvenile shrimp: 0.2mg/L-0.5mg/L, adult shrimp: 1mg/L-2mg/L). Chlorine dioxide ≥10d, sulfamethoxazole ≥30d, florfenicol ≥7d. 1. Do not store chlorine dioxide in metal containers. Do not mix with other disinfectants. 2. Do not use sulfamethoxazole with acidic drugs. 3. Do not let povidone iodine come into contact with metal objects. Do not mix directly with quaternary ammonium disinfectants.

Table 4 Treatment methods for common diseases of freshwater shrimp (continued) -1 Shrimp disease name Symptoms Treatment methods Withdrawal period Notes Black gill disease The gill filaments of diseased shrimps are black and partially rotten. Some diseased shrimps are accompanied by black spots on the sides of the cephalothorax and plastron. The vitality of diseased juvenile shrimps is weakened, they swim slowly at the bottom, their phototropism is weakened, the metamorphosis period is prolonged or they cannot metamorphose, their abdomens are curled up, their body color is white, and they do not eat. When adult shrimps are sick, they often float on the water surface and move slowly. 1. Black gill disease caused by bacteria: Feed with oxytetracycline 80mg/kg body weight or florfenicol 10mg/kg body weight mixed with bait for 5d to 7d, and double the dosage on the first day. For prevention, halve the dose and use it continuously for 3d to 5d. 2. Black gill disease caused by excessive suspended organic matter in the water: regularly spray the entire pond with 15mg/L~20mg/L quicklime. Bleach ≥5d, oxytetracycline ≥21d, florfenicol ≥7d. 1. Do not use oxytetracycline with aluminum, magnesium ions and halogens, sodium bicarbonate, and gel. 2. Do not mix quicklime with bleaching powder, organochlorine, heavy metal salts, and organic complexes. Black spot disease will cause black ulcer spots on the carapace of shrimp. In severe cases, the shrimp will be greatly reduced in vitality, or lie on the edge of the pond in a dying state. Keep the water clean, and carry water during fishing, transportation, and stocking to prevent damage to the shell of the parent shrimp. After the onset of the disease, spray the entire pond with povidone iodine (juvenile shrimp: 0.2mg/L~0.5mg/L, adult shrimp: 1mg/L~2mg/L). Povidone iodine should not come into contact with metal objects. Do not mix with quaternary ammonium disinfectants directly. Parasitic protozoa can be seen under microscopic examination, such as worms, polycystic ovary worms, bell-shaped worms, and shell sucker worms parasitizing on the shrimp body and gills. In severe cases, a layer of fluff can be seen with the naked eye. 1. Spray 1mg/L to 3mg/L zinc sulfate throughout the pond. 2. Spray 1mg/L potassium permanganate throughout the pond. Zinc sulfate ≥ 7d. 1. Do not use metal containers to hold zinc sulfate. Pay attention to pond oxygenation after use. 2. Potassium permanganate should not be used under strong sunlight.