Aquaculture is now very mature in many areas. With the increase of culture density, some fish diseases have also appeared. Some farmers blindly use drugs or don't know how to use them, which has caused great losses to them. Here, the usage and basic knowledge of fish medicine are introduced for everyone to learn and use.
First, correct diagnosis and timely medication.
In the process of fish disease diagnosis, it is necessary to find out the cause of fish disease and master the condition. Any disease happens for a reason. There are three main causes of fish diseases: first, bad external stimuli, including mechanical damage, physical or chemical stimuli and pathogen infection; Second, the body is malnourished and lacks some necessary nutrients; Secondly, the defects of the body itself. The occurrence of any disease has both certain internal factors and certain external conditions, which are usually called the three major pathogenic factors: the organism itself, pathogens and the environment. Among them, evil plays a major role in the occurrence of diseases, because it determines the occurrence and basic characteristics of diseases; The environment will affect the role of pathogens. Although it cannot cause diseases, it can promote or hinder the occurrence and development of diseases.
A correct understanding of the cause and condition of the disease can help us understand the nature of the disease and formulate effective treatment and prevention measures. It is necessary to diagnose fish diseases accurately. First of all, we must have a full understanding of the ecological conditions, water quality and feeding conditions of the pond in order to correctly grasp the external causes of the disease; In addition to visual inspection, it is best to do further inspection. Only through dissection and microscopic examination, combined with the symptoms of sick fish, can fish diseases be correctly diagnosed. Generally speaking, different fish diseases have different symptoms, but some fish diseases have similar or identical symptoms, such as VC and VB2 deficiency, fulminant hemorrhagic disease and severe fish liver disease. Fish diseases with similar or similar symptoms should be carefully identified and the right medicine can be given after diagnosis.
For the sick pond, take medicine in time after diagnosis, and don't delay time. Because fish live in water, it is difficult for us to master some of its activities, and so is the situation after illness. Once sick fish are found, their appetite often decreases, which makes the treatment more difficult. If we don't take immediate measures to control the disease, the sick fish will probably die because of the aggravation of the disease, and the pathogen will also take the opportunity to speed up the spread. In severe cases, it is likely to spread to the whole pool, causing serious consequences. Only in the early stage of fish disease, when the sick fish still has a certain feeding ability, can it be treated in fish. Otherwise, it is difficult to control the disease only by disinfecting the pool water with external drugs. This is of course very important for treating bacterial and viral fish diseases, and also plays an important role in preventing the secondary infection of invasive fish diseases.
Second, symptomatic drug selection and correct medication
No medicine can cure all diseases. If it is not used properly, it can not only prevent and treat diseases, but may even aggravate diseases and cause greater economic losses. Different fish medicines can be effective for different fish diseases. Generally speaking, bacterial fish diseases should be treated with oral and external antibacterial drugs; Parasitic diseases should be sprayed with pesticides in the whole pool or medicine bath. When choosing fish medicine, we should pay attention to avoid using the same medicine for a long time to prevent and treat a certain disease or a certain kind of disease, so as not to make pathogens resistant, resulting in decreased or even ineffective efficacy. At the same time, we should also pay attention to the reliability and safety of drugs. Some drugs have a strong enrichment effect in organisms, such as hormones, antibiotics, mercurous nitrate, formalin and so on. The use of such drugs will directly affect the quality of fish products and human health, so special attention should be paid. When using this kind of drugs, we should arrange the withdrawal period reasonably or choose drugs with less side effects and toxicity and poor curative effect to replace them. Therefore, we should pay attention to the feasibility of drug use when choosing drugs. In addition, the selection of drugs should pay attention to the adaptability of cultured varieties to drugs. For example, trichlorfon is commonly used for silver carp, bighead carp, grass carp and carp, but not for California bass and freshwater pomfret. In addition, different fish have different reactions to the same drug at different growth stages, such as grass carp, silver carp and other fish are sensitive to copper sulfate, and the concentration of copper sulfate exceeds 1 mg/L, but freshwater pomfret still has no abnormal reaction when its concentration reaches 5 mg/L; The fry of grass carp and silver carp are more sensitive to copper sulfate and bleaching powder than adult fish, so they should be used with caution when disinfecting.
The development direction of fish medicine in the future is "three effects", which is efficient, quick-acting and long-lasting; "San Xiao" has little toxicity, side effects, small dosage, no teratogenicity, carcinogenicity, mutagenicity and Chinese herbal medicine. If possible, it is appropriate to choose new drugs, but we should proceed from the local reality and consider factors such as source, price and actual effect. Don't blindly choose the products of regular manufacturers to avoid losses.
Fancy fish
Third, combined medication and reasonable compatibility.
In most cases, when two or more drugs are used at the same time, the effect of one or two drugs will always be affected. Synergy will enhance the efficacy, while antagonism will reduce the efficacy. Some drugs will also produce toxicity and cause harm to fish. Therefore, in the combination of drugs, we should make use of the synergistic effect between drugs to avoid the incompatibility. Generally speaking, the combination of many antibiotics will also produce the above synergistic or antagonistic effects. Antibacterials can be divided into two categories according to their functional properties: the first category is bactericidal antibiotics. Including penicillin series, cephalosporins, aminoglycosides, bacitracin, polymyxin and so on. The second category is antibacterial antibiotics. Include chloramphenicol, tetracycline, erythromycin, oxytetracycline and sulfanilamide. When the first kind of antibiotics are used together, the bactericidal effect can be enhanced or added. When the second kind of antibiotics are used together, it can increase the bacteriostatic effect, but it will not enhance the bactericidal effect. The combination of the first and second antibiotics can produce antagonism. In addition, when antibiotics are mixed with other drugs, interactions may also occur. For example, sulfonamides and trimethoprim (TMP), bromogeramine and potassium permanganate, hydrogen peroxide and glacial acetic acid, rhubarb and ammonia water can produce synergistic effects, which can increase the efficacy; Tetracyclines can form chelates with aluminum, magnesium, calcium, iron and other metal ions in antacids, which makes it difficult for intestinal tract to absorb, thus reducing the role of antibiotics. This deserves special attention.
Because fish medicine has its uniqueness in the use method. Therefore, most drugs for external use will be affected by water medium to a certain extent. When multiple drugs are used at the same time, the interaction is particularly obvious. For example, the commonly used quicklime is not only antagonistic to copper sulfate, bleaching powder and chlorine-rich, but also influenced by phosphorus or ammonium nitrogen in water. Similarly, phosphorus or ammonium nitrogen will also react with quicklime, reducing fertilizer efficiency, so it should be staggered for 5 ~ 7 days in production. When calcium lime meets trichlorfon, it will play a synergistic role in medicine, and some trichlorfon can be transformed into dichlorvos with greater toxicity, which is also the fundamental reason why the mixture of trichlorfon and surface alkali commonly used in China can have higher efficacy.
There is also a commonly used mixture of copper sulfate and ferrous sulfate, which also uses the synergistic effect between drugs to better exert the efficacy. However, when copper sulfate meets salt in alkaline water, it will produce antagonism between drugs and affect the efficacy. Therefore, in the comprehensive prevention and treatment of diseases with multiple drugs, we must pay attention to their antagonism and synergy, and determine the use method and dosage increase or decrease according to the specific situation.
Because fish live in water and the environment is complex, we can't feed fish medicine like other animals, so we must be more careful when we find that fish are sick, so as not to overdo it or overdo it, so as not to completely cure fish diseases.