In production practice, whether it is prevention or treatment of aquaculture diseases in China, it is too dependent on drugs to kill pathogens. Ignoring the immunity of the farmed animals themselves, the leading role in disease resistance and disease prevention, and the role of the self-purification ability of the ecological water environment of the pond. The repeated intensification and emphasis on disease prevention measures is only reflected in the increase in the frequency of drug spills and the number of times of internal medication bait.
Especially in the past decade or so, disease prevention and control measures have become more and more emphasized, more and more strengthened, and the cost of drug application has become higher and higher. However, contrary to wishes, the disease is becoming more and more serious and more difficult to treat. Outbreaks of diseases are widespread and long-lasting, and the loss of dead fish caused by diseases is increasing. At the same time, the quality and safety of aquatic products are more and more important, and the requirements for water environmental protection are becoming more and more stringent. Under the pressure of multiple pressures, higher requirements have been put forward for aquatic disease prevention and control practitioners.
Under the guidance of the existing traditional aquaculture disease prevention and control concept measures, can we effectively achieve "reduced dosage of drugs"? Can aquaculture achieve "zero medication"? Under the premise of "zero drug", how to carry out scientific water quality management? How is algae management carried out? Under the premise of "zero drug", how can we effectively prevent and control diseases?
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In response to the above confusion, we have set up a column of "Fishing Connoisseur Salon", inviting industry insiders and practitioners who are willing to think and explore the future of the industry to discuss and think about how our aquaculture industry can achieve environmentally friendly, circular and sustainable green development.
Can aquaculture achieve zero medication
Awareness of sporangiasis
Sharing guest: Jiang Fajun
From May to June 2013, in the carp farming agglomeration area, many ponds showed the early symptoms of carp's so-called "acute rotten gills", and the pond fish were intolerant of low oxygen, and generally floated on the surface of the water during the day, showing a roaming state. In severe cases, the more in the afternoon and evening, this roaming state is more obvious (in fact, mainly because the water quality deteriorates, the ammonia nitrogen exceeds the standard, the pH remains high in the afternoon, and the ammonia poisoning phenomenon occurs, commonly known as "dark floating head").
Picking up the roaming carp, opening the gill lid for naked eye observation, the gills have a large amount of mucus, hanging swag, the gills are black, the gills are rotten, and the microscopic examination shows that the gills are filled with a large number of spore worms and sacs containing small gametes. This was seen on many microscopic examinations in 2013, when it was thought that sporidium was the main cause of the "acute rotten gills" of carp.
However, carp supra-gill sporidium does not present the traditional lesion, that is, the formation of bean-shaped or rice-grained milky white sacs of different sizes visible on the gill arch, but is evenly dispersed on the gill flakes like milky white pus. Due to the lack of information and literature on spore worms at hand at that time, coupled with their lack of knowledge of sporangia, their classification, life history, etc. are not clear, so the treatment of sporidium is based on traditional treatment methods.
Treatment with traditional medicines such as dichlorzalide, chlorphenidine hydrochloride, or levamisole hydrochloride, or octathion, or dimethoate, is initiated, and spore shedding or reducing effect is not obvious. However, in the subsequent actual cases, although the shedding of sporidium is not obvious, as long as measures to improve the water quality environment are taken and blind application of antibiotics and water disinfectants is prohibited, the condition can be greatly alleviated and the crisis can be lifted.
Therefore, in May and June of the following year (2014), I encountered cases of this kind of stress disease, and even if there were a large number of spore worms on the gills, I ignored the spore worms and did not dwell on the sporozoites and indiscriminately applied insecticides. Starting only to improve the water quality and taking some corresponding measures, the result was that the stress symptoms disappeared and the crisis was lifted. Later, microscopic examination found that the spore worms parasitic gills of fish were significantly shed or reduced.
The gills of fish are filled with a large number of spore worms that will definitely damage the gills and affect respiratory function, just as people suffer from pneumoconiosis. People suffering from pneumoconiosis will not endanger life, but only affect the shortening of life, affect people's quality of life, work ability, etc., but for carp for people to eat, as long as it is not immediately life-threatening, others do not have to worry, do not consider the length of life of fish, young fish will be eaten and consumed.
On the other hand, it should be acknowledged that people are helpless or powerless in the treatment of spore worms. Knowing that we cannot do it indiscriminately is the main folly of people's fish disease control. The use of drugs such as dichlorpride, chlorphenidine hydrochloride or levamisole hydrochloride is not effective in treating spore worms, blindly changing other insecticides, or adding several insecticides to mix administration, or increasing the dosage of the drug, these blind tossing behaviors can only make the situation worse.
The gills of the fish are filled with a large number of spore worms is only the cause of the death of the carp rotten gills, of course, it is best to eliminate the cause, if not, then it is necessary to fully realize this, the pond fish are not tolerant of low oxygen. In the daily management of ponds, attention is paid to improving the self-purification ability of water ecosystems, and measures are taken to improve the water quality environment to avoid the occurrence of hypoxia caused by large amounts of oxygen consumption in ponds. Perhaps by doing this, the fish's autoimmunity can completely promote the shedding of the sporangia.
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