In recent years, the river crab has become one of the main species of artificial breeding and artificial breeding.

With the increasing stocking density of Eriocheir sinensis and the destruction of the culture environment, the diseases of Eriocheir sinensis are becoming more and more serious, which poses a great threat to the culture of Eriocheir sinensis and brings huge losses to farmers.

After collecting, sorting out and studying a large number of data and cases, more than 500 front-line technicians in China have come to the conclusion that to control the outbreak of crab diseases, we should mainly start with the breeding environment, the purchase of fry, the protection and rational use of aquatic animals and so on. In a word, it is a healthy and efficient breeding model of Yumeikang, which is "nurturing but not preventing, strengthening the body and eliminating evil".

Through this model, we can achieve high efficiency and high yield, reduce unnecessary economic losses of farmers and friends, and improve economic benefits at the same time.

The following is the author's experience in crab disease prevention in the past few years, hoping to help the majority of farmers.

enteritis

Symptoms: the overall food intake in the pond mouth is reduced, some crabs poured out of jejunum and cages have poor vitality, slow movements and are not easy to turn over, and some sick crabs will spit yellow foam at their mouths.

Uncover the shell to check whether the intestine, the jejunum of the inner intestine and the outer intestine are red, swollen and free of feces. Squeezing by hand will have turbid liquid, accompanied by edema and liver problems.

Etiology: Generally, the inducement of enteritis is poor water quality and partial decay of aquatic plants, mainly bacterial infection caused by animal feed (chilled fish) or feed mildew, and may also be exogenous imported pathogenic bacteria.

The main pathogens are Aeromonas hydrophila, Salmonella and Escherichia coli, which are highly contagious.

Suggestion: Step 1: Remove the dead crabs in time, and then proceed to the next operation.

Step 2: Sprinkle special iodine in the whole pool and take Kangmei 2+6+ Shuijin+Kangbeining orally.

The third step: Dikang 1+ Dikang 3 changed the bottom, replenishing water and detoxifying.

Step 4: spray tea aldehyde in the whole pool for disinfection.

Rotting gills

Symptoms: Infected crabs have discolored gills, yellowish or black gills, inflammation, local ulceration, decreased vitality of sick crabs, slow movements, difficulty breathing, reduced food intake, and even death in severe cases. The disease mostly occurs in the middle and late stage of crab culture.

Etiology: Gill is the respiratory and excretory organ of Eriocheir sinensis, which maintains the metabolism of the whole body.

Under normal circumstances, the gill function of Eriocheir sinensis is damaged, so there will also be liver atrophy, severe liver necrosis, and a little carelessness will lead to death.

Rotten gill disease is mainly caused by bacteria, mainly Vibrio, Aeromonas and Edwardsiella. The deterioration of water quality, harmful bacteria in sediments, long-term feeding deterioration or moldy bait are the main factors inducing gill rot.

Suggestion: Dikang 1+ Dikang 3 is modified, and the whole pool is sprayed with special iodine for disinfection. Take Kangmei 2+ Kangmei 6+ Jinshui+Kangbeining orally, and then use special iodine three days later.

Attached to the crab body surface

Symptoms: There are attachments on the body surface of crabs, which are slippery and look a little black when touched by hands. Crabs eat little, and they scratch grass actively. At the same time, they will come out on the shore at noon and their claws will be propped up.

Other colors look like moss or a layer of mud.

Harm: The vitality of the Eriocheir sinensis attached by ciliates will gradually weaken, leading to nutrient deficiency, physical decline, slow growth, easy to die in the pond, dirty body surface, selling price difference, unable to sell a good price, resulting in gill damage, leading to difficulty breathing of Eriocheir sinensis, secondary bacterial infection, leading to a large number of Eriocheir sinensis deaths.

Etiology: Crab ciliary disease is a parasitic disease common in autumn crabs. The pathogen is caused by ciliates parasitic on the body surface, appendages and gills of crabs.

Often feeding chilled fish, the residual bait and feces are deposited on the bottom of the pond, and the bottom of the pond is poor and dirty, and there are too many rotten grass and residual bait and feces, and the water quality is polluted without paying attention to changing the bottom and adjusting water, which provides favorable conditions for ciliates to breed.

Suggested scheme:

Dikang 1 Improve the sediment, decompose the organic matter in the water with Bacillus, and treat the ciliates on crabs with Jiangsu No.2.

Shuipingzi

Since 15, "edema disease" has become one of the main diseases of river crab culture, and its incidence and spread have basically swept through the main culture areas in China, bringing huge economic losses to river crab farmers.

The root cause of hydronephrosis is controversial. At present, experts in the industry have not reached a conclusion, and opinions vary. Some people say that hydronephrosis is caused by Vibrio or Aeromonas hydrophila, while others say that it is caused by microsporidia infection.

Personally, I think there are many reasons for shrinkage.

Show symptoms:

Poor vitality, not eating much, not molting, or difficult to molt, white erosion of liver and pancreas, it is difficult to distinguish liver filaments. When the shell is opened, there will be a lot of body fluids, the gill surface is complete, the muscles are atrophied, the appendages have a lot of tissue fluid, the shell is thin, the exoskeleton is soft when pinched by hand, and there is basically no food or yellow in the intestine, that is, the hepatopancreas is discharged.

These are typical symptoms.

The factors that may induce this disease are as follows

Seedling problem: catching up with the epidemic this year, the management of stranded crabs after wintering is neglected, and the nutrition can't keep up. At the same time, the demand for seedlings increased a lot in February, and many people used drugs to drive seedlings, polyester and other drugs, and the damage to seedlings can be imagined.

Problems of aquatic plants: the density of aquatic plants is too thick and unevenly distributed, which will affect the flow of water and make the water layer. Sufficient dissolved oxygen in the upper layer and insufficient dissolved oxygen in the bottom layer will affect the feeding of crabs, and the pH value will increase greatly.

The weather has changed abnormally this year: the temperature rose slowly at the beginning of the year, but it caught up with the epidemic and it was impossible to go out to feed crab seedlings. After the epidemic ended, crabs were detained in the pond and began to be fed in large quantities. The early consumption of animal bait was too large, which affected the digestive system of crabs. If the bait can't be digested well, it will be excreted, which will lead to a seemingly large appetite of crabs. In fact, crabs are not nutritious enough, which also increases water pollution.

There is plenty of rain in June, and the continuous rainy days are extremely abnormal, which also has a great influence on the occurrence of water accumulation.

Harmful bacteria: Bacteria in normal ponds include beneficial bacteria and harmful bacteria.

What we are doing now is high-density culture, which has high requirements for the overall environment, especially for strains. Generally, it is Vibrio, Aeromonas, Aeromonas hydrophila, Escherichia coli, Salmonella, etc. It is very common in crab ponds. These are relatively harmful strains. It is necessary to sterilize and supplement beneficial bacteria regularly, so that the number of beneficial bacteria in the pond is higher than that of harmful bacteria, so as to achieve the effect of bacteriostasis with bacteria! Generally, liver necrosis will be accompanied by edema, enteritis and other symptoms when doing examination!

Dietary nutrition: the first is feeding. There must be no moldy feed, especially animal feed, and there must be no deterioration. Feeding with these baits is tantamount to poisoning! Then, through a large number of practical cases of Tangkou, the author found that the probability of water shrinkage of Tangkou is very low when it is taken orally regularly, and the probability of treating water shrinkage by taking orally regularly is about 80%.

Oral combined packaging: Kangmei 1+ Kangmei 2+ Kangmei 6+ Shuijin.

Kangmei 1 mainly aims at improving intestinal tract, digestion and absorption of lactic acid bacteria; Kangmei 2 has a great effect on the repair of crab liver; Kangmei 6 is mainly a kind of encapsulated vitamin, which participates in the metabolism of the whole body and helps the recovery of crab constitution. Water gold, the main component of which is Ficus carica polysaccharide patented product, can improve the antibacterial and antiviral ability of crabs, improve immunity and increase the compressive ability of crabs! !

Dissolved oxygen problem: continuous rainy days this year, low air pressure and more rain will lead to lack of oxygen in the water.

The temperature has not risen in July, and low water temperature will also lead to bad eating of crabs and low immune function.

There are too many aquatic plants and too thick, and the water body can't circulate, so it will lack oxygen.

Continuous rainy days must prevent aquatic plants from rotting, and continuous rainy days will also cause water turbidity, bottom heat, bottom return and bottom hypoxia.

Regular use of Dikang 1+ Dikang 3 can reduce the bottom heat and reduce the oxygen debt, which is a dissolved oxygen factor and very important.

Drug residue: For this factor, we should start with fry. Many owners of crabs want to raise a large number of fry in a short time, and generally use drugs to drive away the fry, such as polyester, which will make the fry slightly poisoned. This is a very common and important factor in the breeding process.

In addition, in the process of adult crab culture, if there are lobsters in the pond, special drugs will be used to drive them away, which will stimulate and kill them, and so will crabs, and slight poisoning will occur again.

There is also pest control, which involves choosing some drugs from informal small manufacturers and blindly pursuing the effect. The drug residue is quite heavy, and the crab is also slightly poisoned. Generally speaking, eating becomes worse, activity becomes worse, and then the transparency of water becomes higher. This phenomenon is very many, these are very important factors, but we usually ignore it.

slows

Symptoms: In the early stage of crab tremor, sick crabs eat little or nothing, molting is difficult, and their mobility is weakened.

Sick crabs have symptoms such as persistent trembling, convulsion and limb spasm, and their appendages are weak, so they often shake every time they touch them.

Sometimes the feet are folded and curled up into a ball, so some places call it loop leg disease or trembling disease.

_ Sometimes it is light rust-colored or slightly black, often lying on the shore or beside aquatic plants, and does not feed.

Pathogen: The pathogen of the disease is still inconclusive. Viruses and spiroplasma are the mainstream reports, and Eriocheir sinensis reovirus is the most commonly reported virus pathogen.

Inducing factors: the dissolved oxygen at the bottom of the pool is low for a long time, especially in high temperature weather, and the trembling disease is serious at this time.

A large number of aquatic plants rot, and river crabs will suffer from a large number of diseases after climbing their heads due to severe hypoxia.

Usually, I like to treat problem ponds with irritating drugs, such as killing insects and cyanobacteria (or moss), with a high incidence.

Ponds that are fed in large quantities and cannot be eaten are also prone to illness.

In areas where pond cleaning is incomplete or impossible in the early stage of aquaculture, the incidence rate is also generally high.

Preventive measures: to prevent "trembling disease", we should start from eliminating the source of the disease.

1. pond cleaning: use quicklime or bleaching powder to dredge and disinfect the pond mouth, with the dosage of 500kg and 80kg per mu respectively.

After disinfection, the water is discharged and dried in the pond for 2 ~ 3 months.

2, the choice of crab seedlings, Yumeikang crab seedlings, the quality is guaranteed and traceable.

3. Water plant management, accounting for 30% of the whole pond is enough, not too much, and too high pH is also one of the inducing factors.

4. Strengthen the regulation of water quality and sediment, and improve sediment regularly, once a week for Dikang/KLOC-0, once a week for Yangshuibao, once a week for Junmei No.2 and EM parent bacteria.

5, feeding bait, reasonable nutrition, can not have mildew deterioration, especially animal bait, can not be fed too much.

6. Comprehensive treatment from the aspects of physiology, intestine, liver and gallbladder.

Ecological attention should be paid to controlling the total amount of sediments in the water environment; Attention should be paid to the rational layout and feeding mode of aquatic plants in production, and scientific pond management should be carried out.

Crab slave disease

Description: The sick crab grows slowly, its gonads are underdeveloped, and it is difficult to distinguish between male and female.

When the crab slave is seriously parasitized, the crab meat becomes smelly and inedible, commonly known as "worm crab"

The disease is easy to occur in salty and fresh water ponds with high salt content.

Symptoms: The abdomen of the sick crab is slightly swollen. Open the umbilical cover, you can see milky white or translucent granular worms, about 65438±0mm thick, parasitic on the accessory branches or chest plate. Sick crabs grow slowly, and crabs seriously parasitized by crab slaves have a foul smell and cannot be eaten. The main causes of this disease are the high salt content in the pond water, the large number of crab slaves and the spread of larvae.

The onset season is from June to September, especially in August.

Etiology: The crab slave worm parasitizes the abdomen of the crab, and the worm body is divided into two parts: the crab slave outer body and the crab slave inner body. The former protrudes from the host body, including stalk and hatching sac, and is usually an interumbilical granule. The latter is a branched tubule, parasitic outside the crab, extending into the host, spreading to the muscles, nervous system and internal organs of the trunk and appendages of the crab, forming white linear branches with a diameter of about 65438±0mm to absorb the nutrition of the crab.

(Excerpted from Baidu)

Defensive measures: thoroughly clean the pond and kill the crab slave.

From seedling selection, strict screening, regular bottom modification, egg oxidation, regular observation in cages and regular disinfection.

Self-cutting regeneration

Crabs have a strong ability of self-repair and protection.

When subjected to intense stimulation, hypoxia, poisoning, mechanical damage or inability to shell, the food intake is insufficient and the stocking density is too high.

In addition, there is the phenomenon of broken claws escaping. For example, if humans suddenly catch crabs, if they only catch 1-2 feet, they will quickly fall off their attached feet and escape, and then grow new feet.

Especially when catching a large number of crabs, we sometimes see that the size of crab pliers is very different, which is the result of self-cutting and regeneration.

Crab self-cuts and regenerates, and the severed limb has a fixed part, always between the base joint and the seat joint of the appendage. The structure here is special, which can stop bleeding and regenerate new feet.

The phenomenon of self-cutting and regeneration of crabs only exists before the young crabs shed their shells, and the sexually mature crabs have no regeneration function.

When many such cases are found, 1+ Kangmei 2+ Kangmei 6+ Jinshui+Hard Shell Bao should be taken orally to supplement nutrients and trace elements.

Black and yellow bottom plate

Forming factors: There are two factors. Crabs belong to benthos, and the quality of crabs is determined by the quality of water and sediment: 1. Cause of sediment, such as sulfur, iron, ammonia and other elements.

2. In the late stage of river crab culture caused by poor management, due to the increase of feeding amount, a large number of residual bait and feces were not decomposed in time, aquatic plants rotted and a large number of algae died and sank to the bottom of the pond, forming a large number of organic matter and organic debris, which were fermented and rotted with the participation of bacteria, leading to acidification, black and smelly bottom mud.

Acidic corrosive substances are piled up at the bottom of the pond. Crabs live in such an environment, and the floor is easily corroded by acidification. The corroded parts lose the protection of the outermost layer, become unsmooth and dull, and the floor is yellow and black, which not only looks bad, but also affects the quality and sales of river crabs.

Preventive measures: regularly maintain aquatic plants and plant grass fertilizer.

The aquatic plants in the pond are rotten or there are no aquatic plants. Take out the aquatic plants that can be fished out to prevent further decay. Go to Dikang 1+ Junmei 2 regularly. When the water quality is fresh, you can catch some aquatic plants in the pond. Use aquatic plant dew regularly to ensure the nutrition of aquatic plants.

Regularly use EM parent bacteria to adjust water quality.

In severe cases, citric acid should be used appropriately.