Since May 2022, there has been a marked increase in diseases of aquaculture species. California sea bass, yellow bone fish, raw fish, forktail, grass carp, etc. in the Pearl River Delta region have all experienced daily loss of fish, which lasted for a long time, and the use of various drugs did not have obvious effects.
After controlling the amount of feed fed, the amount of death is significantly reduced. These are some of the main common features of this year's disease. The variety of diseases is widespread, the onset time is long, the cure is difficult, and the feeding is prone to problems, especially the last point, which will directly cause the rise in the cost of breeding, and the growth rate of fish will be relatively slow. These factors have many subsequent effects. For example, the time of fish production will be significantly lower, and the material ratio will be higher.
Below is a look at the photos of California sea bass diseases collected in Tangtou
These pictures of sick fish take pictures of fish that have just died in the fish pond, and it can be seen that the gills of California sea bass have whitish mucus and mucus on the gills, which is more obvious symptoms of bacterial infection. The circumferential cavity may be seen as the so-called blood sinuses caused by significant blood stasis. The body surface is bright in color, and no obvious wounds are seen. Pond diseases are caused by some fish with rotten head or tail and some with decay wounds on the back.
Fishing live fish can also have significant gill bleeding symptoms. As shown in the following figure
The symptoms of gill bleeding are very obvious, the internal organs of the liver and intestines are partly whitish, and they are also in a state of ischemia, and some fish have ulcerated wounds on the surface of the body and the tail of the fish is missing. Long-term gill bleeding caused by the lack of total blood in the fish, the heart does not have enough pressure to inject blood into the whole body, which is the cause of the ischemia and whitening of the liver of the internal organs, and the blood color is relatively dark and not bright red, such blood lacks oxygen, but also can not flow smoothly caused by circulation. It is also the cause of blood stasis near the periachmal cavity, the so-called blood sinuses.
When the fish body is in this state, the stress resistance is very poor. For example, eating a little more than a few, can not digest and is easy to die because of the increase in oxygen consumption in the digestion and absorption stage, even when eating materials, it is easy to die immediately because of intense exercise to grab the material, a rainstorm caused by stress will also die immediately, or the water body nitrite is slightly higher, reducing the ability of hemoglobin to bind oxygen in the fish, and the number of dead fish will increase rapidly. At this time, if you disinfect and kill insects, it will be easy to cause the rapid death of fish with insufficient blood in such bodies.
Insufficient blood in the fish body, it is impossible to ensure that the fish body surface has sufficient mucus, there is no adequate protection, the fish body will fester within three days after being bitten by insects or bacterial infection. A fundamental disease that California sea bass urgently needs to address. That is, the problem of gill bleeding must be dealt with first, and then the blood is filled by the hematopoietic tissue of the fish body, and then the current disease of California sea bass can be treated.
This can also be seen by comparing the 2020 and 2022 California perch rots.
Pictured above is a photo of a California perch in 2020
This is a photo of a new dead fish fish caught in a fish pond in 2022
The same is the fish that just died, the severity of the rotten body in 2022 is far more than that in 2020, the wound of the rotten fish in 2020 is relatively neat, the wound can be seen at the healthy fish tissue structure is relatively tight, the body surface of other parts is relatively normal, and the normal tissue observed at the wound decay wound in 2022 is also in a state of erosion, and the irregularity of the rotten wound is more obvious. The same is rotten, and the two kinds of rotten body conditions are actually obviously different.
In 2020, the analysis of the situation is that nutrients such as fat are deposited in capillaries, causing local tissue capillaries to block the blood flow can not bring sufficient oxygen and nutrients to the festering tissue, so that this part of the tissue cells lack sufficient material basis and immunity is lacking, such as lack of mucus on the surface, so that insect bites or bacteria can be directly infected, resulting in local ulceration.
Of course, it can be seen from the wound that the rotten body at this time is mainly rotten in the early stage, and there will be rotten body in the middle and late stages of the body, such as back ulceration, etc., the wound is generally more neat, the heart is the origin of the blood, the large and small blood vessels are like rivers, the blood is a river flowing in the blood vessels, and after some of the vascular pipes become narrowed or blocked, the blood will choose the side branches to infiltrate. After too many blocked capillaries caused by too many blood nutrients, the tissue area that needs to be supplied to blood will die. Then the necrotic characteristics of the organization will have a distinct appearance very neat.
This feature is related to the distance between the blockage site and the heart, of course, the blood in the fish body is full of abundant is the premise of ensuring the tight organizational structure of the uncorrupted area. Only the fish of one atrium and one ventricle at this time are still relatively easy to cure with water disinfection and internal treatment, and the fish body still has a certain anti-stress ability. However, fry are not well able to resist stress in the unset state, such as fish fry in the pond that are prone to mass death within a week if disinfected.
The wounds of the rotten body in 2022, coupled with the observation of the gill ischemia of the surviving disease fish, the reason for the rotting body such as 2020 is that the ischemia in the fish is a very important premise of the disease, the gills and kidneys, intestines can be seen in the anatomy of bleeding, after the body ischemia, the rot of the distal end is more obvious, such as rotten head and tail is more common. The anti-stress ability of the fish body is relatively poor, and if it is disinfected at this time, it will often be obvious that the number of dead fish will increase, and the number of dead fish is not easy to decline. After the incessant bleeding of the gills and so on causes ischemia in the body, the amount of hematopoiesis cannot make up for the missing amount, and the heart does not have the ability to pump blood to fill the whole body. This can be seen from the picture, there is a more obvious blood accumulation near the periachal cavity, forming the so-called "blood sinus". This is different from the situation of the "blood sinus" in 2020. The difficulty of treatment for onset in 2022 will increase considerably.
In the case of lack of blood in the body, the type of death increases significantly, many body surfaces are not missing, and even the gills are not obvious, but the water temperature rises, nitrite, ammonia nitrogen, water organic matter is more, and the amount of feeding is slightly increased, that is, the amount of death increases significantly, and many fish body surfaces that die are normal. And it died for months on end. Of course, in addition to the anatomical observations, there are also theoretical inferences. These dead fish have not occurred in previous seasons of high temperatures.
For example, at 24 degrees of water temperature and 30 degrees of water temperature, the oxygen consumption of the fish body will increase by 5 times on an empty stomach, that is, the water temperature of 30 degrees is about 5 to 6 times that of the 24 degrees water temperature. The oxygen consumption of fish in the fasting and satiety digestion stages is also very different, and the satiety digestion stage is 5 to 6 times the oxygen consumption of the fasting stomach, which is an important experimental data for inferring that ischemia in vivo ischemia from gill hemorrhage. The dissolved oxygen required by the tissues in the body is mainly supplied through the blood circulation system of the fish, and the high water temperature in July of 2022 has no appearance diseases, and the death of the slight feeding is significantly increased, and even if the feeding is not added, the fish will die every day. In this way, it is impossible to ensure that the body has sufficient dissolved oxygen to meet the dissolved oxygen required for temperature change at high water temperatures, and the gap in dissolved oxygen is even greater after eating. This is an objective and simple truth, the dissolved oxygen of the water body is the foundation, and the dissolved oxygen in the body is the key.
At this time, if the nitrite in the water body is high, the oxygen carrying capacity of the blood in the fish body decreases, the dead fish will increase significantly, the organic matter in the water body will increase, and the oxygen consumption will increase The dead fish will also increase. Higher water quality conditions are required. The water body is cleaner. Algae should also be very abundant, and the amount of dissolved oxygen in the water body is rich enough to slightly improve the effective dissolved oxygen in the fish body. This is also part of the pond mouth using clean water, cultivating algae, while using more anti-stress measures, the amount of death will be significantly reduced, but can not be added. A little addition will increase the death. Of course, breeding is a business, long-term can not add feed, fish growth slow feed ratio is high, the cost itself is increasing, coupled with continuous loss, the level of aquaculture profitability does not dare to predict.
The blood in the fish body can not fill all the tissues, except for the protection without mucus, it is easy to infect insects and bacteria, such as the gills are easy to grow various insects, but also easy to infect bacteria. There are also blood spots deposited in the fins of the fish, which can be understood, the arteries can not pump blood at full pressure, the veins can not return all the blood back to the heart, and then the bleeding points remain on the fins. These are found in California perch, yellow bone fish, and raw fish. This blood is usually present in a dotted form. Of course, it is also a reverse proof of insufficient blood. Fish tissue is due to lack of nutrients and cellular metabolism disorders, and the scales are loose and easy to lose scales, and the mucus is relatively small. Mucus deficiencies such as yellow bone fish are more serious. It is easy to infect bacteria, and once the amount of stress activity increases, it is easy to quickly consume dissolved oxygen in the body and tissue failure.
This situation also makes it difficult for California perch to produce fish. It's hard to raise fish and it's hard to sell fish. California perch has long-term gill bleeding, and there is not enough blood in the body, so that the net is easy to die, commonly known as hard bone. Mainly the ability to resist stress is seriously insufficient. Originally, there was still some blood in the body to maintain the vitality of the body, and the amount of stress activity of a pull net increased, and the dissolved oxygen in the body was exhausted and died. Can't get on the fishing cart. Fish that barely get on the bus are not resistant to transportation, have a large loss on the car, and the survival time of the next level, such as the end market, will be reduced. Eventually, it will also cause no one in the market to sell the fish and the price will plummet. Of course, California bass is supported by the national market. When you arrive at the terminal market, you will die in the fishmonger's stall within a week, so that the terminal sales are valuable, but the price of the pond will not rise without the sellers.
Taken together, the treatment of the current California sea bass disease requires the following steps
1. Internal administration should control the problem of gills, intestinal and renal organ capillary bleeding.
2. Enhance the hematopoietic function of the fish body and restore the total blood volume of the fish body.
3. Control the water quality and the abundance of algae, and avoid fish body stress.
The first two points of treatment are very difficult, for example, gill bleeding is a world problem. This disease is the former crucian carp big red gills, which has not been effectively solved for several years. Crucian carp culture has decreased significantly. In the trial of the effect of tangkou mixture internal administration to see to solve this problem.
The experimental pond mouth about 50,000 California perch, the average size of about 4 two / tail, feeding 5 packs per day, 60-70 deaths per day, has been continuous death for about 1 month +, continuous internal administration for 7 days (July 1 to 7), the number of deaths reduced to 10 +, stop internal service, while controlling feeding to maintain 5 packs / day, follow-up has been reduced. There was no recurrence as of 12 August. On 13 August, 13 dead fish began to appear, with rotten heads and tails, indicating that the internal medication regimen can effectively control gill bleeding problems for one month. According to Tangtou tracking, the current onset of diseases such as rotten head and body only takes 3 days. Therefore, an internal dose to ensure that the gills do not bleed for one month.
Pond mouth 2, 3 about 140,000 fish, that is, each pond mouth 70,000, the onset of disease at the end of May, after a variety of treatment, the effect is not good, the loss of 300-500 fish per day. The average specification is about 4 two. July 9 began to take internally, a week after a week the amount of death decreased tail about 70 tails per day, feeding 10 packs per day, the situation of the previous feeding that is, the situation of dead fish floating disappeared, continue to use for 7 days, feed 9-10 packs per day, the amount of death decreased to about 50 tails, during this period occasionally added to the death is increased, this time the temperature is hot, the water temperature is higher than 38 degrees, continue to reduce the feed to 7 to 9 packs, to the 30 days the amount of death is significantly reduced to about 10 tails per day. The dissection of the fish in a bad state was found to have disappeared, but the internal organs were obviously not infiltrated with blood. As shown in the following figure:
At this time, the feeding to 10 packs will also increase the number of dead fish to about 50, because of the long-term disease, there are about 65,000 fish in the pond, and the feeding to 10 packs is more than 1.5 packs per 10,000 fish, and the water temperature belongs to the feeding amount is relatively high. The phenomenon of gill bleeding can be seen in fish with poor anatomical vitality, but there is no blood in the liver and intestines of the fish, and this color of the liver cannot be used as a criterion for the quality of the liver and gallbladder liver, because the naked eye can see that the liver is more homogeneous and delicate, and there are a few fat particles. However, the analysis of the essential reasons, there is sufficient blood supply on the gills, but there is no internal organs, indicating that this is still the total amount of blood is insufficient, that is, hematopoiesis has not kept up. As a result, the subsequent liver is not red and fat deposition problems are caused.
But hematopoiesis can only be obtained by digesting and absorbing nutrients from the feed. When there is not enough blood, once such a fish eats too much food and increases the oxygen consumption in the body during the digestion stage, the body will die of hypoxia. Therefore, it can only be added slowly, but slowly added, the cycle of internal service will be long, and the cost will be relatively high. This is the second difficulty of treatment. Sick fish need to eat to adjust well, but if they eat more, they will die. Of course, the feeding rate of these two ponds has been relatively high, there are more fish, and the onset time is relatively long, and some fish do not eat for a long time, and there is a great relationship between not eating materials. The time to completely repair it will be long, after the complete repair, there will be no problem with 1.5 packs per 10,000 fish in the high water temperature season, and the specifications will be larger to an average of 5 or 5, and it is normal to eat two packs of materials per 10,000 fish per day and the above materials. However, the current period of high incidence of disease is indeed very tangled. You can only add ingredients slowly and increase the time of internal service in exchange for repairing each fish as well as possible.
Of course, in the process of treatment, also taking into account the water quality, the abundance of algae was significantly improved with the blessing of the bacillus internal administration program. Such as the following pictures.
After about a week of internal administration, the algal phase in the pond is obviously rich and maintained for a long time, so that the oxygen production capacity is enhanced, and the indicators such as nitrite and ammonia nitrogen in the water body are very low. It effectively improves the ability of fish to obtain dissolved oxygen from water bodies, which has a positive effect on repairing the body of fish. At the same time, it will also lock trace elements in the ecological cycle of the entire pond, and these substances absorbed by the water body in the algae will be absorbed into the body by the food chain into rotifers, branches, small fish, etc., and absorbed into the body by California perch, which has a positive significance for body repair.
In short, the difficulty of california sea bass farming in 2022 is significantly increased, but there are still solutions. Compared with previous years, the program for preventing gills and other organ bleeding will be appropriately increased, and quicklime and other disinfectant insecticidal products can only be used after gill bleeding treatment. so as not to cause stress death.
The long-term price of California sea bass is very good, but it has always been very difficult to farm. The problem of capillary bleeding in the tissues and organs described in this article has existed for a long time, which is the current status quo. It is very likely that this situation will exist for many years to come, and this phenomenon is an urgent problem that needs to be solved urgently. It will not be solved naturally because of the decrease in water temperature, but will affect the long-term feeding problem and affect the growth of fish. After the wintering, the spring of 2023 will be a peak period of incidence.
There is still enough time from now to the beginning of spring next year, during this period to do a good job of prevention, the fish body is repaired, the use of low water temperature feed long meat rate is higher, the growth rate of the impact of May be caught up, it is still possible to obtain a very high profit return. The management method is as follows, of course, I have adopted the green antibiotic-free natural return to the basics method to do it. And the ratio is very low in the comprehensive program.
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