Disinfectants are the most commonly used drugs in aquaculture to eliminate or kill pathogenic microorganisms and other harmful microorganisms in the external environment. According to the chemical properties can be divided into aldehyde disinfectants, base disinfectants, acid disinfectants, salt disinfectants, halogen disinfectants, dyes, oxidants, heavy metal disinfectants and other eight categories. There are many kinds of aquaculture animals in China, and the toxicity of different disinfectants to aquatic animals varies greatly. Improper use of disinfectants is easy to cause poisoning and death of fish and shrimp. However, there is still a lack of standard data on the toxicity of disinfectants in China.

1, bleach powder

Calcium hypochlorite, the main component of bleaching powder, produces hypochlorite and hypochlorite ions with bactericidal power when it encounters water. Hypochlorous acid can also release active chlorine and initial ecological oxygen, so as to chlorinate and oxidize bacterial protoplasmic proteins, play its bactericidal role, and have different killing effects on bacteria, viruses and fungi.

In production, the water final concentration of 0.8g/m3 ~ 2g/m3 is usually sprayed in the whole tank. According to the toxicity, bleach powder can be used to treat juvenile shrimp, barb fry, Guangdong bramnard fry and Hainan red

2, sodium hypochlorite

Sodium hypochlorite, commonly known as bleach, is a commonly used chemical disinfectant, with a strong toxicity, not strictly selective to organisms, but this drug is not stable, should pay attention to the active ingredients when used. The mechanism of action is the same as that of bleaching powder.

For production use, it is often sprayed with the final concentration of 1g/m3 in the whole pool. The safe concentration of sodium hypochlorite for young and young Macrobrachium rosenbergii was 40.74mg/L and 18.77mg/L, respectively, which was much higher than the production dosage (0.5mg/L), and could be used for disinfection. The safe concentration for sea cucumber larvae is 0.46mg/L, which is higher than the concentration used in production (0.1mg/L ~ 0.2mg/L), so sodium hypochlorite can also be used as a disinfectant in the process of sea cucumber culture.

3, Sodium dichloroisocyanurate

The mechanism of action of sodium dichloroisocyanurate is the same as that of bleaching powder, which produces hypochlorous acid and hypochlorous acid ions with bactericidal power in contact with water. The bactericidal spectrum is wide, and it has strong killing effect on the propagandists, spores, viruses, fungal spores, etc.

In production, the water final concentration of 0.3g /m3 ~ 0.5g /m3 is usually sprayed in the whole tank. Sodium dichloroisocyanurate can be used to sterilize tilapia, carp, grass carp, wild labeo, wheat labeo, silver carp, macrobrachycarp, etc. However, the safe concentration of the disinfectant for these animals is low, so it is recommended to use a concentration of not more than 0.3g/m3. Both pelteobagrus and catfish are scaleless fish, which are sensitive to this disinfectant, so it is recommended to prohibit the use of this disinfectant in aquaculture.

4, Trichloroisocyanuric acid

Trichloroisocyanuric acid is also known as strong chlorine, the mechanism of action is the same as bleach powder, the validity period is 4 to 5 times longer than bleach powder, is a broad spectrum fungicide, grass carp rotten gill disease, enteritis disease, red skin disease have significant effects, on fulminant fish disease, white skin disease, printing disease, white head and white mouth disease and other diseases have excellent effects.

In production, the final concentration of 0.1g/m3 ~ 0.3g/m3 is sprayed in the whole tank. According to the sensitivity of aquatic animals to trichloroisocyanuric acid, Chinese Barb

5, Bromochloroheine

Bromochlorhain is an efficient, broad-spectrum disinfectant with a wider pH range than conventional chlorine-containing disinfectants and a better killing effect. In water, it can continuously release active Br- ions and Cl- ions to form hypobromic acid and hypochlorous acid, and achieve the purpose of sterilization by oxidizing biological enzymes in microorganisms.

In production, prophylactic drugs are sprayed with 0.2g /m3 in the whole tank, and sterilization and disinfection are often sprayed with 0.3g/m3 ~ 0.4g/m3 in the whole tank. Bromochlorhexine can be used as a disinfectant for catfish, eel seedlings, grass carp fry, yellow catfish, clam, rainbow trout fry and so on. In addition, bromochlorhain has a high safety factor for eel species, grass carp fry, clams and rainbow trout fry, so it is a good choice to use bromochlorhain as a disinfectant for these aquatic animals.

6, Dibromoheine

The hydrolysis rate of dibromine is relatively fast, and it can continuously release HBrO(active bromine) in water, and penetrate the cell wall of microorganisms to destroy the cell protein, produce irreversible oxidation and decomposition of the internal structure of its cells, and finally play a bactericidal effect.

The conventional application dose in production is 0.3g/m3 ~ 0.4g/m3. The safe concentrations of beautiful white shrimp, grass carp, juvenile carp, juvenile chain sturgeon, juvenile jellyfish, carp, white cloud mountain fish, spotted forktail ð«š” and other aquatic animals were higher than the conventional amount, and the safety factor was higher

7, Chlorine dioxide

Chlorine dioxide is a strong oxidizing agent, and the action mechanism is different from that of general chlorine preparations. Activated chlorine dioxide produces a new ecological oxygen with strong oxidation under the action of hydrogen ions, which can quickly attach to the cell surface of microorganisms, penetrate into the cell membrane of microorganisms, and make microbial proteins lose vitality to achieve the purpose of killing microorganisms.

The usual dosage in production is 0.1g/m3 ~ 0.3g/m3 water final concentration of the whole tank. Tinca Phoxinus, Carassius auratus Xiangyunyunensis, lake whitefish larvae, Clams, Procambarus clarkii seedlings, macrobrachium nipponense, macrobrachium rosenbergii seedlings, green shrimp seedlings, eel seedlings, grass carp species, Clams and Chinese eriocheir species can all be used as disinfectant. Chlorine dioxide is highly toxic to juvenile Stipalus japonicus and juvenile chain sturgeon, and it is easy for juvenile Stipalus Japonicus to die. These two kinds of chlorine dioxide should be prohibited in aquaculture.

8, Formalin

Formalin is 40% formaldehyde aqueous solution, has a strong pungent odor, can coagulate proteins and dissolve lipids, denaturate proteins, has a strong broad spectrum bactericidal and insecticidal effect.

Formalin can be used as both a disinfectant and a pesticide. Generally, the final concentration of 10g/m3 ~ 30g/m3 in the water tank is used for fish disease prevention and control, and the final concentration of 15g/m3 ~ 20g/m3 in the water tank is used for shrimp and crab disease prevention and control. It can be used as juvenile Spinibarbus chinensis, juvenile double-sawed fish, Takifugu melanogaster, reticular grouper, Sudanfish, juvenile Macrobrachium roseni, juvenile Macrobrachium Roseni, juvenile red eye trout, juvenile Spinibarbus Chinensis, Guangdong gurney, Hainanensis erythroculter, juvenile lake whitefish, yellowfish, koi, Moon Butris, American eel, southern Macrobrachius Chinensis, juvenile juvenile Xishi tongue, double-spiny yellowfish, and Australian gemstone It is a bactericidal disinfectant for juvenile bass, goldfish, silver bass, hybrid sturgeon and other aquatic animals with less toxicity. When the concentration of formaldehyde is 11.3g/m3, it has no effect on the development of the larvae, and can be continued to use, and can improve its survival rate. The safe concentration of formaldehyde for the flea-like larva (Z1-Z6) in each stage is 30mg/L, 32mg/L, 11mg/L, 4mg/L and 9mg/L, respectively. Therefore, the use of formaldehyde is a safe concentration before Z4, and it may be unsafe to use for too long in Z5 and Z6 stages.

Because the safe concentration of Tinca Xinus, Tang fish, Leiocassis larvae, long-rostris Leiocassis, Qihe Cario and erythroculter is lower than the usual dose or similar, it should be used with caution or not. Some people have used formalin in sea cucumber culture, resulting in the death of all sea cucumber skin, so it should be prohibited in the process of sea cucumber culture. Formalin in the production as a large amount of sprinkled drugs, economic is not cost-effective, generally used as a dip drug for the prevention and treatment of fish disease, can be used for fine scale fish species, river catfish, goldfish, yellow catfish species and other aquatic animals, the prevention and treatment of fish disease is safer.

9, Potassium permanganate

Potassium permanganate is a strong oxidizing agent, and its aqueous solution can contact with organic matter, release new ecological oxygen, quickly oxidize organic matter, oxidize the active group and sulfhydryl group (-SH) in enzyme protein and protoplasmic protein into disulfide chain (-S-S) and deactivate, thus playing a bactericidal role.

The common dose of production is 2g/m3 ~ 5g/m3. The whole pond sprinkling is used to prevent and control bacterial diseases of fish. The eel seedlings were sprayed with 1g/m3 of water final concentration, and the adult eels were sprayed with 3g/m3 of water final concentration. Control shrimp disease with 2.5g/m3 ~ 5g/m3 concentration of the liquid soak for 4 hours to 6 hours after a large amount of water change. Potassium permanganate is less toxic to Chinese Spinibarbus larvae, river crab larvae, large yellow croaker, koi carp, European eel, American eel, southern large mouth catfish larvae, and ptychocephala, and can be used in disease control, but the administration of eel should be cautious. In addition, potassium permanganate can be used to sterilize the fry of megalobrama, the juvenile shrimp of red crayfish, and the species of grouper of salmon.

Potassium permanganate is toxic to eel seedlings, Tinca Xinus species, Tangfish, netted grouper, Dendrobrachii larvae, Sudanfish, juvenile Macrobrachii Roseni, juvenile Macrobrachii larvae, juvenile Stichopus japonicus, red eye trout, grass carp species, mixed abalone, juvenile carp of Qi River, erythroculter culteri, Chinese dace larvae, eel species, goldfish, Zander species, beautiful white shrimp, rainbow trout fry, hybrid sturgeon, silver perch and so on It is large and should be used with caution or prohibited in production. If the concentration of potassium permanganate is higher than 1.6ppm, it will produce strong toxicity to the mud snail embryo, resulting in embryo death. The safe living concentration of potassium permanganate for plankton larvae is 0.5ppm, but if the concentration is more than 2ppm, it will have a greater impact on the creeping larvae, so pay attention to the dosage in mud snail culture.

10, Quick lime

The main component of quicklime is calcium oxide, which is a convenient, cheap and efficient disinfection drug. When mixed with water, calcium hydroxide is generated and a lot of heat is released, which can quickly dissolve the cell protein membrane and make it lose vitality, so as to kill the pathogens in the pool and the enemy organisms remaining in the pool. When used for sterilization and treatment, pay attention to the change of pH value of the water body, and cannot be excessive, because when the pH value of the water body is greater than 7.5, the quicklime can quickly increase the pH value to form a strong alkaline, which is easy to cause dead fish.

The commonly used sprinkling concentration in production is 15g/m3 ~ 30g/m3. The final concentration of 16.5g/m3 ~ 27g/m3 was applied to the whole shrimp pond. It can be used as disinfection drug for the production of Guangdong gurnard fry, Hainan erythroculter, Lotia, southern catfish fry, and erythroculter erythroculter. However, the safe concentration of quicklime in Guangdong gurnard fry, lotia, and erythroculter erythroculter is lower than the common concentration, so pay attention to the dosage when using.

Quicklime is very sensitive to Odontobutis odontobutis and young prawn of macrobrachium roseni, and should be prohibited in production.

11, Sodium chloride

Its aqueous solution can be used as a hypertonic agent, through the immersion method to change the osmotic pressure of pathogens or their attached organisms, so that the equilibrium of the liquid inside and outside the cell will die or fall off from the fixation, and it is widely used in cold water fish culture.

The use of sodium chloride as a leach medicine can be used as a disinfectant for fish such as Tang fish, long-rostris synodontis, red eye trout, spinibarbus fry, Guangdong megalobrama fry, Hunan erythroculter, lake whitefish juvenile, lepidodont species, Ophiocephalus ophiocephalus, salamander species and so on

12, Povidone iodine

Povidone iodine is a water-soluble polymer which can release iodine slowly by combining molecular iodine with PVP, and maintains a dynamic balance between the two. Its bactericidal activity is the affinity of the membrane provided by the surfactant PVP to bind the iodine contained in it to the membrane and cytoplasm to oxidize or iodize sulfhydryl compounds, peptides, proteins, enzymes, lipids, etc., so as to achieve the purpose of bactericidal. It is a broad-spectrum disinfectant, which has different degrees of killing effect on most bacteria, fungi and viruses, and is mainly used for disinfection of fish eggs and aquatic animal body surface.

In production, 1% POvidone iodine is commonly used to splash the whole tank, so that the final concentration of the pool water can reach: 0.2g/m3 ~ 0.5g/m3 for fish and shrimp, 0.3g/m3 ~ 0.7g/m3 for turtle and frog. It is safe to use POvidone iodine in aquaculture such as red eye trout, Tinphoxinus fish species, abalone variegatus and silver bass. The safe concentrations of POvidone iodine for the shell larvae of shrimp scallops, gulf scallops, oyster larvae and oyster larvae at eye point stage are 3.25mg/L, 3.17mg/L, 4.48mg/L and 4.44mg/L, respectively. Therefore, POvidone iodine can be used as a disinfectant for these aquatic animals, but attention should be paid to the safe concentrations at each larvae stage.

Most of the data in this paper were obtained under laboratory conditions, and the pond culture environment is much more complex, and the drug effect is often affected by many factors such as water temperature, water quality, pH value, hardness, plankton and organic matter, and in disease prevention and control, disinfectants are often used together with pesticides or antibacterial agents, in this case, Antagonistic synergies between drugs often lead to changes in drug toxicity, so technicians and farmers should use drugs according to specific circumstances. It is best not to exceed the safe concentration.