on measures for the prevention and control of spring carp viremia (IHC)
1. General Provisions
1.1. Spring carp viremia (VVK) is a highly contagious viral disease affecting carp, Cyprinus carpio L. The disease proceeds as an epizootic and is characterized by the development of a septic process and mass death of fish.
1.2. The disease is common in European countries with developed carp farming (from the Urals to the Atlantic), for which a fairly long winter period of low temperatures is characteristic.
1.3. The disease manifests itself in the form of exudative-hemorrhagic syndrome, known in Russia under the name "rubella". The development of the syndrome is due to the multiplication of the virus in the endothelium of the blood capillaries and kidneys, which leads to disruption of the water-mineral balance and the release of plasma and cornea shaped elements into the surrounding tissues and body cavities.
This syndrome also underlies two bacterial diseases of carp - aeromonosis and pseudomonosis.
1.4. The causative agent of the disease was also found in a number of other cyprinids and catfish.
2.1. The disease causes a rhabdovirus from the genus Vesiculovirus. This is a bullet-shaped RNA genomic virus with a size of 105-125x70-85 nm. The virus is called Rhabdovirus carpio, a synonym for spring viraemia of carp virus (SVCV).
2.2. VVC virus is represented by one serotype, but has common antigenic determinants with pike fry rhabdovirus, PFR in G, M and N proteins, which cross-react using MFA, ELISA, immunoblotting and complement-dependent neutralization methods.
2.3. Among field isolates of the virus, both avirulent and highly virulent isolates are found.
2.4. The most susceptible to the virus is the EPC cell line, as well as the FHM, ICO and TmB lines (bulbus arteriosus of Mozambique telapia). The optimum temperature for in vitro reproduction of the virus is 20-23 ° C.
3.1. In addition to carp, the VVK virus was found in goldfish, as well as grass carp, white and spotted silver carp, when the latter were grown in polyculture with carp. Outbreaks of epizootics caused by him have been recorded in juvenile common catfish under conditions of industrial cultivation.
3.2. The main areas for the distribution of IHC in Russia are the Krasnodar Territory, the Rostov Region and the Central Black Earth Zone. Cases of the disease were noted in the Sverdlovsk and Tver regions. The main route for the distribution of IHC is inter-farm transportation of fish.
3.3. The most susceptible to the disease is carp. At the same time, he noted significant intrapopulation (individual) and interpopulation (intraspecific) variations in susceptibility. Outbreaks of the disease usually occur in springtime (April - early June), but are sometimes recorded in the fall. During experimental infection, grass carp is more stable than carp, and is even more resistant to silver carp disease.
3.4. The disease contributes to a significant decrease in fish resistance after prolonged wintering at low water temperatures. The disease is provoked by stressing the fish during the unloading of hibernation, transportation and transplantation of fish for feeding.
3.5. Under production conditions, the disease is mainly affected by yearlings and two-year-olds, less commonly, biennials and three-year-olds of carp. The death from VVK was also noted at the repair and manufacturers. In the case of acute epizootics, 40-45% (sometimes up to 70%) of the herd may die. Herbivorous fish at the age of one year and older do not usually get sick, but can be carriers of the virus.
3.6. The most acute IHC occurs at a water temperature of 11-17 ° C and attenuates when it increases to 20 ° and above. At a temperature of 5-10 ° C, the infection proceeds chronically, but death can reach 100%.
3.7. The susceptibility to the disease decreases with age. Larvae and early fish juveniles are most sensitive to experimental infection. Mass death of juveniles under the age of 8 weeks is observed even at a water temperature of 20-24 ° C, which is explained by the incomplete formation of the immune system in fish of this age. However, outbreaks of disease in young fish of the cyprinid family were not observed in fish farm conditions.
3.8. The virus can be isolated from carp before the onset of the disease, most easily during epizootics in spring or autumn.
3.9. The reservoir of infection is formed by sick and recently dead fish, as well as virus carriers. Weed fish can also be carriers of infection. Infected fish secrete the virus with urine and secretions from the intestines, epidermal-mucous compartments, exudate of skin blisters, extremely rarely with sexual products and possibly through the gills.
3.10. The virus is transmitted through water, silt, fish stock. In water at 10 ° C and dried sludge at 4-20 ° C is stored for more than a month. The mechanical carriers (vectors) of the virus are blood-sucking parasites of fish - leeches and argumentus, as well as fish-eating birds, in the stomach of which it remains for several hours and can be thrown out with burped food.
3.11. The gates of infection are the gills, probably intact skin and the initial section of the digestive tract. The infection is generalized in nature, a septic process develops, leading to the defeat of almost all organs and tissues.
3.12. An ill fish acquires stable immunity, antibodies appear in the blood, the level and duration of circulation of which are determined by the intensity of the infectious process.
4. Clinical signs and pathological changes
4.1. In yearlings of carp, the incubation period for natural infections ranges from 1 to 4 weeks.
4.2. The first signs of the disease are anorexia and depression of fish, they accumulate in shallow areas of the pond and acquire a dark body color. The disease proceeds in acute, chronic and nervous forms.
4.2.1. Acute form
Sick fish gather at the water supply, their breathing is quickened. On external examination, focal or diffuse erosion of scales, an increase (stretching) of the abdomen, pinpoint hemorrhages (petechiae) on the abdominal surface, at the base of the pectoral, abdominal, anal and caudal fins and in the interradiation of the fins, hemorrhages in the scaly pockets and sickle-shaped hemorrhage are noted during external examination. Apple. Gills are anemic (sometimes almost gray) with petechiae. Later, exophthalmos develops, from the inflamed, protruding anus, long strands of a grayish or milky-white shade of mucous consistency appear, sometimes with an admixture of blood. Part of the fish observe the formation of skin blisters filled with transparent exudate and resulting from exfoliation of the skin from the underlying scales. Occasionally, abundant epidermal-mucous compartments with a grayish tinge hanging over the rags appear on the entire surface of the body. Exudate blisters and epidermal-mucous compartments contain a large amount of infectious virus.
At the final stage of the acute form of the disease, local prolapse of the scales is noted. These areas of damaged skin can become a place of settlement of the second microflora and the subsequent development of ulcers. Of the fish with an acute form of IHC, only a small fraction recover.
4.2.2. Chronic form
In 5-7% of diseased fish, the disease from the very beginning of the epizootic proceeds in a chronic form. Chronically ill fish have a darker color, are depressed and do not feed. Occasionally, they can observe minor hemorrhages on the surface of the body or in the eyeball. Respiratory movements rapid, gills anemic, often with foci of necrosis. Progressive exhaustion develops, leading to the inevitable death.
4.2.3. Nervous form
It occurs at the final stage of epizootics in 3-5% of diseased fish and is associated with the penetration of the virus into the central nervous system. Sick fish usually look healthy in appearance, but upon careful examination, an increased tone of skeletal muscles is noticeable, all fins are straight and tense, muscle tremors are observed. The reaction to external stimuli (sound signals, feeding) is inadequate: the fish begins to rush around the surface of the water, trying to jump out, swims in a circle or in a corkscrew. Attacks of increased excitability alternate with phases of inhibition.
4.2.4. During experimental infection of the larvae and early juveniles of carp and herbivorous fish in diseased individuals, depression, rapid breathing, hemorrhage on the surface of the body, edema of the caudal stem, redness of the abdomen and anus (enteritis), and hydrocephalus (swelling on the head in the form of a cap as a result of accumulation of exudate in the head) are noted cranial cavity). Some ill fish develop paralysis of the lower jaw (the mouth does not close).
4.3. An autopsy in fish with an acute form of the disease reveals hydremia of tissues and muscles, edematous, swollen internal organs and an accumulation of transparent yellowish (sometimes bloody) exudate in the body cavity. The liver is unevenly colored, pale, dark gray, sometimes clay-green in color, the gall bladder is enlarged, filled with bile. The buds are swollen, flabby. The spleen is dark cherry in color. The intestines are empty, with signs of catarrhal (less often - hemorrhagic) inflammation. Parenchymal organs, heart, intestinal wall, swim bladder and skeletal muscle are mottled with petechiae. In fish with chronic and nervous forms of IVC, pathological and anatomical changes are less pronounced.
4.4. Sick fish usually have some signs of disease from the above complex. Only in individual affected individuals during the period of epizootic can the whole set of characteristic clinical and pathological anatomical changes be found.
5. The diagnosis
5.1. A preliminary diagnosis of IHC is made on the basis of an analysis of epizootological data, detected clinical signs and pathological changes. The final diagnosis is based on the results of a virological study on the isolation and serological identification of the virus. IHCs are differentiated from pseudomonosis and aeromonosis, guided by the provisions of the relevant instructions.
Virological work - sampling and processing of samples, isolation and identification of the virus, bioassay and serological studies - is carried out in accordance with the "Instructions for the application of traditional methods for the diagnosis of viral infections of fish".
After delivery of the selected material to the laboratory, they immediately proceed to its processing.
5.2. For virological studies, material is taken from clinically ill fish during an epizootic period at a water temperature of 11-17 ° C. At the same time, the selection of material is carried out in the absence of disease on the farm in the case of studies of fish grown in it for virus carriage. To isolate the virus, the collected materials inoculate the EPC cell culture. The inoculated culture is incubated at 21-22 ° C.
5.3. Identification of the isolated virus is carried out in a neutralization reaction using hyperimmune serum. When working with epizootic material, the formulation of the reaction is combined with the isolation of the virus. An EPC cell line is used in the reaction.
5.4. For the diagnosis of IHC, it is necessary not only to isolate and identify the virus during the period of epizootic, but also to show that its content in fish tissues was at an epizootically significant level (not lower than 10 5 TCD50/ g) and, more importantly, to prove its etiological role, reproducing the disease and the death of fish in a bioassay. The latter condition is of particular importance in the context of a significant fluctuation in virulence in field isolates of the virus and the existence of other diseases with similar clinical manifestations.
5.5. A biological sample with isolated virus is placed on yearlings or year-olds of carp weighing 20–40 and 5–10 g, respectively. After infection, the water temperature is raised to 13–15 ° C during the day. In case of experimental infection by the method of baths or intraperitoneal injection of virus-containing material, the incubation period is 4-10 days.
5.6. In the summer, if necessary, a preliminary assessment of the epizootic situation in the farms by IHC is carried out by serological examination of farmed fish.
5.6.1. Blood serum is taken from biennial or three-year-old carp 1.5-2 months after an epizootic or a period of favorable water temperatures for the development of infection (in the absence of a disease). This is usually done in the middle or end of June.
5.6.2. The reaction is carried out using the complement of fish, which increases the sensitivity of the method for detecting antibodies to the virus of IHC on average 10 times. The source of complement is fresh normal blood serum of carp, which is introduced into the composition of the working dilution of the virus in an amount of 20%. The reaction uses an FHM cell culture as highly sensitive in detecting fish antibodies to the virus. The inoculated culture is incubated at 21-22 ° C.
5.6.3. The detection of virus-neutralizing antibodies in fish sera is the basis for a preliminary conclusion about the dysfunction of the economy (reservoir) and conducting direct virological studies in it in the spring of next year.
6. Preventive measures
6.1. In order to prevent the penetration and spread of VVK in the farm, fish hatcheries and veterinary requirements set forth in the Veterinary and Sanitary Rules for Fish Farm approved by the Department of Veterinary of the Ministry of Agriculture and Food of the Russian Federation should be met. It is necessary to ensure optimal hydrochemical and hydrobiological regimes in ponds, not exceed the norms of fish landing densities, feed them with specialized balanced feeds, and minimize fish stress during technological manipulations with it.
6.2. The farm carries out regular veterinary monitoring of the health status of fish in the time frames specified in the above Rules, paying special attention to the examination of fish in the spring.
6.3. The import of fish and caviar for breeding and rearing purposes is permitted only from fish farms and fishery reservoirs that are safe for infectious and invasive diseases and are carried out in accordance with the provisions of the Veterinary Department's Instructions for Veterinary Oversight of the Transport of Live Fish, Fertilized Caviar, Crayfish and Other Aquatic Aquatic Animals organisms. "
6.4. If the IHC is suspected during a fish examination by a veterinarian, the farm managers and specialists, under the supervision of the local state service, organize the delivery of live fish or pathological material (selected in accordance with the current Methodological Instructions for virus identification and laboratory diagnosis of fish viral diseases) to the appropriate diagnostic laboratory for virological studies or call the specialists of this laboratory to select material on site.
Until a final diagnosis is established, the export of fish to other fish farms and fishery ponds, as well as fish transplantation from suspected pond dams within the farm, is prohibited.
7. Control measures
7.1. When a diagnosis is established, the economy is declared dysfunctional in spring viremia of the carp and quarantine is imposed on it. Regardless of the form of infection — carriage of a virus or a clinically occurring disease — the fact that the virus is isolated from fish is sufficient to quarantine. The problems of the economy are reported to the fish farms, in which they exported fish for cultivation and breeding, and to the local public service bodies in charge of these farms.
At the same time, the veterinarian must:
inform the chief veterinarian of the district and the higher veterinary authority about the occurrence of the disease and the area of its spread,
to clarify the time of occurrence of the disease and the number of dead fish of all age groups separately,
to establish where the infection could have entered the farm, and in the event of its alleged importation with fish received by the farm, notify the state public service authorities of the region where the imported fish came from,
take measures to speedy stop and eliminate the disease.
7.2. Under quarantine conditions in dysfunctional fish farms are prohibited:
- export of caviar, fish, fodder aquatic animals and plants from quarantine ponds and their import into these ponds, in some cases, with the permission of veterinary authorities, it is allowed to export fish from safe ponds of quarantined farms that are not associated with dysfunctional ponds of the farm, and from certain safe areas of natural reservoirs to other farms and reservoirs with the obligatory subsequent quarantine of its annual,
- transplanting sick or suspicious fish from the pond to the pond inside the farm,
- mixed planting of fish of different age groups,
- visiting ponds by unauthorized persons,
- the use of fish farming equipment used in a dysfunctional pond, in other ponds of the economy.
7.3. In order to eliminate the disease in quarantined farms (reservoirs), the following activities are carried out:
- to work in dysfunctional ponds, special fishing gear and equipment are allocated, permanent workers are assigned to ponds,
- the bodies of dead fish are collected and buried away from water bodies to a depth of at least 1.5 m with preliminary disinfection with a solution of bleach or quicklime,
- live sick fish, upon the conclusion of a veterinarian, is subjected to technical disposal (boiled and fed to poultry, pigs or fur animals).
- the export of marketable fish without signs of disease is allowed directly to the distribution network without overexposure it in the cages of live-fishing bases, the water in which the fish was transported is subjected to chlorination and then poured into a sewer network, and in rural areas it is poured onto fields at a distance no closer than 500 m .from water bodies, containers after transporting fish are disinfected.
7.4. Measures to improve the economy should be carried out in strict accordance with the plan developed by the local authority of the state veterinary service, approved by the district administration.
7.5. Small full-descending hatcheries, individual ponds, hatcheries, especially if they are located on a safe water source, must be healed by flying and carrying out a complex of all fish-reclamation and veterinary-sanitary measures. Organize the mandatory disinfection of shoes and clothing of personnel working on a reservoir, fishing gear and equipment.
7.6. In large farms located in a region unsuccessful due to the disease, with non-empty or partially empty ponds, as well as in closed natural fisheries, a complex method of eliminating the disease, designed for the gradual improvement of the economy, is used. In accordance with it, measures are being taken to identify and destroy sources of infection, rupture pathogens, improve the physiological state of fish and increase their resistance to disease, and change the environment of fish habitat to the side that impedes the development of the disease. In a dysfunctional farm, strictly comply with the requirements stipulated by the "Veterinary-sanitary rules for fish farms".
7.6.1. They provide enhanced flow of water and take measures to enrich it with oxygen.
7.6.2. In order to improve the sanitary-epizootic situation, chlorine lime or calcium hypochlorite is added 2-3 times during the summer period with an interval of 8-15 days to dysfunctional ponds.
In ponds with an area of up to 5 ha, preparations are applied over the entire surface of the water based on: bleach (containing 25% active chlorine) 1-3 g / m 3, calcium hypochlorite (containing about 50% active chlorine) 0.5-1.5 g / m 3.
For ponds with an area of more than 5 ha, the amount of the preparation is determined from the calculation: bleach 0.1-0.2 g / m 3, calcium hypochlorite 0.05-0.1 g / m 3, but bring it along the coastline with a width of 5-10 m, what is achieved in this zone, the concentration of the drug is 1-2 g / m 3.
The amount of drug per pond is determined by the formula:
X = K x D x P,
where X is the required amount of the drug (g),
K - a given concentration of the drug (g / m 3),
G - the average depth of the pond (m),
P - the area of the pond (m 2).
When working with bleach and calcium hypochlorite, put on a bathrobe, canvas gloves and safety glasses. The face is protected with a bandage of 2-3 layers of gauze.
7.6.3. To prevent complications of IHC by aeromonosis or other bacterial infections, regular bacteriological monitoring of water and fish is carried out and, if necessary, the necessary medications and measures are used as described in the relevant instructions.
7.6.4. If the causative agents of argulosis and scoliosis are detected on the farm, antiparasitic treatments are carried out in accordance with current instructions.
7.6.5. They do not allow mass congestion and nesting of fish-eating birds on the farm.
7.6.6. In a dysfunctional fish farm, a herd of producers and repairs is formed from fish that have experienced epizootics and are highly resistant to IHC.
7.6.7. In areas of mild climate, it is rational to switch to the developed continuous technology for carp farming (on the principle of a fry pond - a feeding pond), which allows abandoning spring-replanting fish-stressing transplants from wintering ponds to feeding ones.
7.6.8. Prevent infection from entering hatching shops, closed water supply plants and enterprises operating on heated water from thermal power plants, state district power plants, etc., in which the larvae and juveniles of carp and other fish species are reared.
7.6.9. In disease-poor cage farms, in order to reduce fish stress, one should refuse sorting and replanting fish in spring time, if possible by spending them in the previous fall or putting them off for the summer. Maximize the density of fish landing in cages.
7.6.10. In warmwater farms, if conditions permit, it is advisable to minimize the length of stay of fish at low water temperatures in the cold season.
7.6.11. In natural enclosed reservoirs of fishing importance, it is recommended to create spawning-growing farms and hatcheries that fully provide themselves with planting material.
7.7. If recreational activities were carried out by taking the farm (reservoir) to flying, eliminating the herd and performing a complex of fish-reclamation and veterinary and sanitary measures, one year after the outbreak of the disease, quarantine is removed from the fish farm (reservoir) in the prescribed manner, declare it safe and bring in fish from contagious disease-free farms.
Fishery farms that were not fully launched and where a comprehensive method of eliminating the disease was used, quarantine is removed 15-20 months after the last outbreak of the disease, provided that the results of virological studies of fish taken from dysfunctional ponds in spring (water temperature 11 -17 ° C), and a serological study of sera of fish selected from summer from these ponds yielded negative results. The work is carried out in accordance with the provisions of the Guidelines for the identification of viruses and laboratory diagnostics of viral diseases of fish and these instructions. Virologically examine 150 year olds of carp with the calculation of detection of virus carriers. In addition to parenchymal organs, samples of the brain and gills of fish are necessarily included in the selected material.
With the approval of this instruction, the “temporary instruction on measures for the prevention and control measures against spring viral fish disease”, approved by the State Administration for Agriculture of the USSR on 07.07.87, No. 432-3, becomes null and void.
Pike fish - description and habitat
Pike is a biological species of predatory freshwater fish, which is the only representative of the pike family. According to various classifications, this genus includes from 6 to 8 independent species. (By the way, armored pike are fish of a completely different biological family and have nothing to do with real pikes). In Russia, by default, the name pike is understood to be the species of common pike, which is widespread in Europe, most of Siberia, Canada and the northeastern United States.
The maximum pike length reaches 1.5 m with a weight of up to 35 kg, but in practice, individuals larger than 1 m and heavier than 8 kg are extremely rare. This fish has an elongated cylindrical body and a large head with a wide flattened mouth. The body color is quite variable and highly dependent on the environment in which the fish lives. Moreover, not only the color (from greenish to brown) varies, but also the pattern (spots and stripes are possible). Single pike fins have a yellowish-gray color (often with spots), paired fins are orange. Gender differences are visible only in the genital area.
The lower jaw of the pike protrudes noticeably forward and is covered with large, different-sized teeth, which simplifies the reliable grip of the victim. On the upper jaw, the teeth are smaller and directed towards the pharynx, which prevents the victim from escaping from the pike mouth.
Pike - a type of fish that hunts and is not at all interested in plant foods. It lives in flowing lakes and rivers with a calm course, but is not found in small standing ponds and fast stony rivers with cold water.
The pike prefers to hide next to underwater thickets, where it can easily ambush small fish and its other victims. The basis of the pike diet is made up of such species as roach, silver bream, gudgeon, perch, ruff, scavenger, etc. At the same time, pike do not disdain to eat young animals of their own species. In spring and early summer, this predator preys on frogs and young crayfish. Large pikes can catch ducklings and small mammals (rats, squirrels, etc.), which for one reason or another find themselves in the water. There are known cases of pike attacks on adult ducks.
In general, pikes are not at all afraid to hunt large prey. Quite often a fish becomes the victim of this predator, the dimensions of which are 50% and even 60% of the size of the pike itself. However, medium-sized pikes, that is, about half a meter, feed mainly on numerous “weed” fish; therefore, this species is invariably used in fish farms to exterminate small ruff and perch.
Like many other predatory fish, the pike hunts from ambush, hiding in the thickets of algae, from where it rushes to its prey. If the ambush is unsuccessful, the pike almost never chases. She always swallows the caught prey from her head, if necessary, turning it in the right direction. In pike hunting, not only vision helps, but also a very sensitive side line.
Under natural conditions, females of this species begin to breed at the age of two to three years, males at four years of age.
Spawning starts soon after the ice melts, when the water temperature does not exceed 3-6 ° C. Females depart in shallow water (depth to one meter), where they begin to splash noisily and actively move within the spawning grounds. Each female is accompanied by several males.
The female is able to lay from 17 to 215 thousand eggs. They are quite large in pike - 3 mm in diameter - and the first days are quite sticky, therefore they often adhere to aquatic vegetation. But then most of them slide to the bottom, where their further development takes place.
Since caviar appears to be in shallow water from the very beginning, with a significant drop in the water level in the reservoir, most eggs die. This, for example, is characteristic of reservoirs, in which the water level is regulated by humans and therefore very variable.
Larvae hatch from eggs during the whole second week after spawning and pass to independent feeding, eating microscopic crustaceans. Reaching a length of 12-15 mm, pike young growth passes to the larvae of carp, which spawns after pike. Five-centimeter young pikes finally switch to fish.
Interestingly, pike river fish often spawn in swimming lakes, which quickly lose contact with the river after the spring flood. With a shortage of food in such reservoirs, hatched fry grow extremely unevenly. Representatives of the same generation may vary in size by 2 or more times. In such conditions, the food chain is built on the basis of cannibalism, when very small pikes feed on plankton, and young animals feed on fry, while at the same time becoming prey for last year's and older pikes. Especially often this happens in Yakutia and northern Canada, where such pike lakes exist on an ongoing basis.
The economic value of pike
In industrial fishing, fishermen rarely rely on pike. Usually it is only a good addition to the target mass fish. This happens for obvious reasons: a pike is a predator, and therefore in a balanced food chain of a river or lake it will, by definition, be an order of magnitude smaller than other fish.
But with sport fishing, pike is one of the most coveted trophies that many fishermen purposefully hunt for. The desire to catch a pike is inherent in sports fishing lovers, not only because it is a very large fish, but also because it is not so easy to catch. Being a worthy rival even for an experienced angler, pike makes much higher demands on him than a bream or carp. Only those who are able to show patience, caution and resourcefulness can catch a pike. In addition, the pike is a family of large fish, therefore, to pull it out of the water, sometimes it requires remarkable strength.
Finally, this predator is just a find for fish farms. If you plan to adapt a large natural reservoir for breeding, first you need to reduce the population of weed fish in it - perch, roach, crucian carp. For these purposes, a pike is launched into the pond, which in one or two years is able to "restore order" in the pond. Also, pike can clear the population of commercial fish from weak and sick individuals. True, you always need to strictly ensure that pike do not massively catch commercial fish, and in any case, you need to catch large pikes that are harmful to the fishing business.
Since ancient times, among all freshwater fish, pike has always been considered a delicacy. Not a single sumptuous feast could do without one or more pike dishes.
Even medieval doctors claimed that this is one of the best fish, because it has great health benefits. Over the past centuries, the opinion of physicians on this issue has not changed significantly, but only found additional scientific justification. Pike meat contains many B vitamins (beneficial for the nervous system), potassium (normalizes blood pressure), magnesium (good for the heart), phosphorus (affects the brain) and other substances.
Like any fish, pike is a dietary product. It contains only one percent of fat, but protein as much as 18%. The energy value of pike meat does not exceed 84 kcal per 100 g. Thus, pike is ideal for those who follow the figure.
This fish has a dry, but tender flesh. Moreover, experts assure that the taste of meat is more pleasant, the larger the pike. However, a very large fish is rather dry, so it is cooked so as to saturate it with moisture. For example, stew with vegetables, stuffed with lard, meat and vegetables, cook fish soup, etc.
In general, the variety of pike dishes is quite large, and the culinary tradition of cooking this fish is hundreds of years old. Pike is baked, fried, stewed, boiled, stuffed, put on soup, cutlets, pastes, etc. The only drawback of pike, for which many people do not like her, is her bones.
Artificial Pike Breeding
As follows from the description, pike is a predatory fish, therefore it cannot be used in fry and growth ponds with carp. Also, it is not used in trout ponds. But she shows herself well in natural lakes, rivers and ponds, where there are a lot of weed fish, which she will eat.
Pike can be successfully bred in lakes with banks abundantly overgrown with vegetation. In such places there is always a lot of small fish, here pike will be easy to hunt. But in ponds poor in vegetation, where there is little fodder fish, it is not possible to breed pike successfully, because from hunger it eats its own young stock.
With artificial breeding, the pike gains weight four times faster than in natural conditions. With the abundance of fodder fish, pike yearlings weigh on average about 400 g, and individual specimens sometimes double as much.
Tribal yearlings are grown in feeding ponds, usually with carp. Many fish farmers leave only young stocks for repair next year, and the rest of the livestock are sent for sale. Second-year pike are allowed to grow in the uterine reservoirs of carp, where they will eat cyprinids and weed carp. In winter, pikes are sent to earthen cages, where one and a half to two dozen year-olds of crucian carp or roach are planted on them for one pike.
If fisheries do not have their own broodstock, wild pikes from natural water bodies are used to produce young animals. Moreover, due to the peculiarities of their physiology, at least five males have to be taken per female. For propagation, earthen cages or small ponds with abundant benthic vegetation are used. The pike will spawn only on it.
Larvae from cages are caught on the third day after their appearance. Not later than the fifteenth day after hatching, the larvae are sent to feeding reservoirs, where they can find food for themselves. To prevent the larvae from catching from spawning grounds on underwater vegetation, they must first be removed.
Since reproduction of pike in ponds is a very troublesome task, it is more preferable to use special apparatuses in which eggs are inseminated and further incubated artificially.
The survival rates of young animals in feeding reservoirs reach an average of about 50%. It is optimal to plant fry in the following proportion: in ponds where there is an abundance of weed fish - no more than 400 per hectare, where it is few - no more than 250, where it is not - up to 120 fry. Three hundred pike fry are planted in large ponds, launched once every two years, per hectare of water mirror.
Pike productivity in the second year of cultivation reaches one and a half centners per hectare.
Visitors to our site who came to this page are most likely interested in the problems of fish diseases. However, before proceeding directly to this topic, one point must be made. Fish are much more ancient animals than humans, their evolution lasted several million years. During this time, fish ideally adapted to living conditions, and their relationships with parasitic organisms are well-established, stable in nature and are rarely accompanied by the death of the host. All those fish diseases that we encounter, in the vast majority of cases, have as their cause gross violations of the conditions of cultivation and maintenance. By eliminating these disorders and relieving stress from fish, you will forever solve the disease problem. In modern ichthyopathology, this is the prevailing point of view, and it is from this position that one should approach all cases of diseases and death of fish. More details on this topic can be found in the monograph, a link to which is presented below.
Among the many factors that can cause fish diseases, oxygen deficiency plays a dominant role. According to statistics from the Central Laboratory of the Ichthyopathological Service (CLIS of the Ministry of Fisheries of the RSFSR), more than 90% of all cases of death and disease of fish to one degree or another were associated with oxygen deficiency. This is a very strong stress factor, greatly weakening the immune system. Therefore, it is necessary to pay close attention to water aeration and control over the content of oxygen dissolved in water.
In addition to killing, the most common causes of fish stress are violations of the hydrochemical regime, temperature differences during transport and transplantation, non-compliance with quarantine restrictions, and the use of inferior or toxic feeds.
Wedemeyer, G.A. Stress and fish diseases / G. A. Wedemeyer, F. P. Meyer, L. Smith, Trans. from English E. M. Naumovskaya. - M.: Leg. and food. industry, 1981. - 127 p. : ill., 21 cm.
Translation: Environmental stress and fish diseases / Bu Garou A. Wedemeuer, Fred P. Meuer, Lunnwood Smith (G. F. H. publ., 1976)
Description of the disease
When a pike becomes infected with a plague, she develops hemorrhagic inflammation of the skinmucous membranes and gills. The researchers found that in freshwater water bodies become the causative agent of the disease Pseudomonas punctataf pelliswhich is identical to the pathogen carmon aeromonosis . However, it does not ferment carbohydrates.
IN brackish inhabit Vibrio anguillarumresembling a flagellar vibrio, very mobile and like a comma. For him, the development of spores and capsules is not characteristic, but it forms acid, promotes hemolysis and thinning gelatin. For reproduction, he needs a minimum temperature of 18 ° C. At the same time, the ability to live is stored at temperatures up to 25 °.
If the water in the pond is fast flowing, then the pathogen in it can remain for several hours. First affected pike with weakened spawning , then the plague appears in a large number of fish, like an epizootic outbreak.
IN March-April month after spawning, plague affects more pikes. Sexually mature individuals become the most susceptible. Prerequisite for flash incidence is Cold Spring. The maximum infection occurs in the middle of summer, and at the end of the summer season the disease subsides.
Depending on the stability of the body of pike, plague can occur in 4 forms:
- Form A. On the body of the fish you can find rounded dry ulcers, bordered with red, 5-10 cm in diameter, sometimes the head can be damaged and the snout may appear.
- Form B. Wet spots with a fuzzy border are visible on the body.
- Form C. Redness can be found on the gills (directly on their inner side), on the mucous membrane of the pharynx, as well as on the skin in the lower body in front. In this case, the head is not damaged and there are no wet spots with open sores.
- Form D. On the surface of the body of the pike, growths and festering wounds are visible.
Symptoms (behavior) of infected fish
Sick fish has a slower movement in the pond, compared with healthy individuals. However, she weakly resists when captured. But free fish, when caught on a hook, often break away from it, and their ulcers bleed greatly. This is due to the fact that soft gelatinous tumors are prone to injury, and the slightest resistance to fish causes breaks with such signs. Fishermen catch such fish mainly in spring and autumn.
Control Measures and Prevention
In order to get rid of infection, it is necessary remove the source of infection from the reservoir, reduce the number of susceptible fish and create an immune herd. If plague is found in a pond, they catch, collect and dispose of infected pikes. When catching, all devices that are used for these purposes must be thoroughly disinfected.
On reservoirs with a dysfunctional epizootic character impose quarantine, and the caught fish must undergo a veterinary examination.
In which ponds are sick
In 1923, the pike plague broke out in Norway, a couple of years later in Finland, Switzerland, Sweden, Denmark, Germany and Australia. In 1930, the disease “reached” the lakes near Moscow, gradually penetrating into the water bodies of Belarus, Klyazma and Pskov. After this, an epizootic of the pike plague broke out in Siberia, on the Middle Volga, in the Yenisei tributaries and in the channel of the Dnieper.
Occasionally, a disease flows in large bodies of water, in lakes and reservoirs for several years in a row. The infection spreads to other bodies of water along with the course of fish migrating or transported on ships.
Is it possible to eat infected fish, a danger to humans
You can’t eat the pike infected with the plague, because with poor roasting, a person can seriously poison. If you cook suspicious fish, then you need to use a high cooking temperature.
In order not to poison your body, you need to know how the sick caught fish looks externally. You also need to have an understanding of the behavior. infected fish in water, and for any signs of plague do not use trapped individuals for cooking.
Fish disease caused by many bio- and abiotic factors environmental factors. These include viruses, bacteria, algae, fungi, helminths, crustaceans, toxic substances, violations of the hydrochemical regime and other components of the external environment.
Infectious fish diseases are caused by viruses, bacteria, algae and fungi. Invasive diseases are caused by parasitic organisms: helminths, protozoa, and crustaceans. There are a large number of non-communicable fish diseases that arise as a result of habitat disturbance. These include nutritional diseases caused by defective or toxic feeds, toxicosis, violations of the hydrochemical regime of the reservoir, temperature changes, excessive gas levels, injuries, etc.
It should be noted that many diseases arise due to a decrease in the immunity of fish due to a variety of stresses. Non-communicable and invasive fish diseases are often complicated by the development of pathogenic microflora.
The clinical picture of a disease usually has a certain specificity. However, in many cases, the clinical manifestations of various diseases are very similar. Since freshwater fish live in a hypoosmotic environment, any metabolic disorders lead to impaired salt-water metabolism: fish develops eye-eye, dropsy, and ruffling of scales. Diagnosis only on the basis of clinical signs in ichthyopathology is unacceptable. For example, ulcers on the body of fish are not always rubella. They can appear as a result of trauma during fishing, fish damage by parasitic crustaceans, leeches, bites of predators, etc. Such signs of rubella as inflammation of the intestine, ascites, eyebrows, ruffling of scales can also appear with coccidiosis enteritis, myxosporidiosis, toxicosis, and some nutritional diseases.
Fish can be a source of disease in humans and warm-blooded animals. In addition to such common helminthiases as opisthorchiasis and diphyllobothriasis, fish sometimes cause foodborne toxicosis and human toxicosis.
The main way of the spread of infectious and invasive diseases of fish is uncontrolled transport from dysfunctional farms to healthy ones. Some fish diseases, in particular, carp rubella, have a natural focal character. This means that in certain regions of the country the causative agents of the disease are found in wild fish living in natural reservoirs. Improving a farm located in the zone of a natural focus of infection or invasion is practically impossible.
Consequently, transporting fish from a given region to a safe body of water is likely to lead to infection. The presence of a veterinary certificate, unfortunately, is not always a guarantee that the fish is healthy. In recent years, cases of the importation of diseased fish into previously successful reservoirs have become more frequent. The importation of cheap marketable fish or fish stock from a disadvantaged region often turns into an economic collapse of the economy. This is especially dangerous for enterprises engaged in organizing fishing and practicing frequent importation of fish from different regions of the country on the principle of "buy where it is cheaper."
Gill disease of unknown etiology (GZNE) or gill necrosis
Gill disease of carp is one of the most dangerous diseases that can cause mass death of farmed fish. The disease manifests itself in the beginning and middle of summer, by the autumn it fades. Most often, two-year-old carp are sick.
The causative agent of the disease has not been identified. Gill disease of unknown etiology should be distinguished from branchiomycosis. The clinical signs of these diseases are largely similar. There are hypotheses about the viral and bacterial nature of the disease. It is noted that often the disease is provoked by violations of the hydrochemical regime, especially the high content of ammonia nitrogen and organic matter. Effective preventive measures aimed at creating favorable growing conditions. The use of bleach or calcium hypochlorite, as well as quicklime, is recommended. Farms that are unsuccessful due to gill disease are subject to quarantine restrictions. The disease can cause significant waste of live fish.
Saprolegniosis is one of the most common fish diseases. It is believed that saprolegniosis is a secondary disease that occurs at the site of traumatic injuries on the body of the fish. In addition to trauma, saprolegniosis appears as a concomitant disease in other diseases, both infectious and invasive. The causative agent of the disease are lower fungi, mainly from the genus Saprolegnia, which are very widespread in nature. Almost all freshwater fish affected by this or that influence or caught in adverse living conditions suffer from saprolegniosis.
Saprolegniosis often occurs in carp fish farms as a result of careless handling of fish, when kept in concrete cages, as a result of trauma during fishing, loading and unloading of live fish. Myths of the fungus penetrate into damaged tissues of muscles, gills, fish skin, destroying tissues. On the surface of the body, the fungus forms a dirty cotton-like coating.
Prevention is the main way to prevent saprolegniosis. All technological operations should exclude fish injuries. For preventive and therapeutic purposes, you can use drugs such as malachite green, diamond green, table salt.
A variety of saprolegniosis is Staff’s disease. It manifests itself mainly in carp yearlings during wintering. With this disease, fungi develop in the nasal cavities of fish. Mycelium of mushrooms in the form of a mass similar to cotton wool covers the head of fish, fungal hyphae can grow into the brain tissue. Staff’s disease usually occurs in winter at very low water temperatures. Although there is evidence that this disease also occurs at a temperature of 5-6 degrees.
Caviar saprolegniosis is the scourge of incubation shops. Caviar of many fish species, mainly salmon and whitefish, is suffering from saprolegniosis. The disease affects, first of all, dead eggs and quickly spreads to healthy eggs. The selection of dead caviar is a laborious, but effective method of preventing saprolegniosis. To combat this disease, malachite green, methylene blue, diamond green are widely used. Water treatment with ultraviolet lamps, ozonation of water also prevent the development of saprolegniosis.
Infectious disease of pond fish caused by a microscopic fungus. Pathogen Branchiomycosis destroys gill tissue. Patients Branchiomycosis fish refuse to feed, accumulate off the coast, rising to the surface of the water, take a vertical position. The disease usually occurs in the summer, lasts 2-8 weeks and causes the mass death of fish. Quarantine is imposed on reservoirs, sick fish and corpses are caught and destroyed. In spring and autumn, ponds are disinfected with bleach or quicklime.
Rubella (aeromonosis) carp is one of the most common and dangerous diseases of carp and carp. In addition to these species, rubella is observed in crucian carp, line, grass carp and some other species, but these cases are usually rare.
Rubella is a contagious disease, which, according to some researchers, is caused by a virus, and, according to others, by bacteria. There is objective evidence in favor of both hypotheses. Apparently, the term "rubella" hides several diseases with similar symptoms. Based on a study conducted by the All-Union Institute of Experimental Veterinary Medicine, it was proposed to distinguish three independent diseases: aeromonosis caused by bacteria Aeromonas punctata, pseudomonosis caused by bacteria of the genus Pseudomonas, and spring viral disease caused by the Rabdovirus cyprini virus (Vasilkov et al., 1978).
Rubella usually occurs in spring or in the first half of summer. Sometimes the disease is noted in the winter. Most often, two- and three-year-old carp are sick. The disease can cause massive waste. In the acute course of the disease, hemorrhages on the surface of the body, dropsy, swallowing, and ruffling of the scales are noted. In the subacute course of the disease, the formation of ulcers that have a whitish or reddish rim is added to the symptoms described above. The chronic form of rubella is most often observed in the second half of summer and is accompanied by the formation of ulcers on the skin and fins. The diagnosis can only be made by a specialist on the basis of a set of studies.
For the treatment of fish, drugs such as chloramphenicol, tetracycline, biomycin, methylene blue and several other drugs are used. In recent years, the use of probiotic preparations has come into practice. Treatment is prescribed only by an ichthyopathologist, taking into account many factors related to a particular reservoir. Unskilled use of antibiotics can cause a negative result.
The only reliable method of improving the economy from rubella is flying, during which the ponds are drained, treated with disinfectants, and fish of all age groups are put into the distribution network or disposed of. If sick fish live in a source of water supply for the economy, it is almost impossible to improve it.
Carp swim bladder inflammation (runway)
The cause of the disease is not fully understood. The most substantiated point of view about the viral nature of the disease. Infection is transmitted mainly through direct contact of sick and healthy fish. Apparently, the pathogen can also be transmitted through water and soil.
Carp, carp, and their hybrids are sick. Occasionally, cases of silver carp, pike, grass carp, crucian carp and pike are noted. The main symptom of this disease is damage to the walls of the swim bladder. Inflammation often affects other internal organs. The disease affects fish of different age groups. Carp yearlings with runway disease usually die during wintering. In the acute form of the disease, massive waste is possible. Over time, fish develop immunity to this disease, and it gradually fades. However, this is only possible subject to quarantine restrictions. There are no specific medicines against this disease.
Fish parasitic diseases
When ichthyopathological study of fish living in natural reservoirs and ponds of fish farms, usually found many parasitic organisms belonging to different species. If the number of these organisms is small, the fish practically does not suffer from their presence. However, at high planting densities characteristic of the production conditions of cultivation, the number of one or more types of parasites can increase dramatically, which leads to disease.
When carp is grown, such invasive diseases as ichthyophthyroidism, trichodiniasis, boneosis, apiosomiasis, phylometroidosis, botriocephalosis, caviosis are most often encountered. These diseases are usually treatable if diagnosed in a timely manner.
This is one of the most dangerous ectoparasitic diseases that can cause massive waste of fish, especially juveniles. Almost all types of fish get sick. The disease causes ciliary infusion, the name of which in Latin translates as "Fish louse with many children." The parasite develops and matures under the skin of the fish, and therefore it is resistant to many drugs that are effective in other diseases. Having reached maturity, the parasitic infusoria leaves the fish, sticks to underwater objects, and forms a cyst. After multiple division, several thousand daughter cells are formed in it. These cells then enter the water and swim freely for 2-3 days. If they manage to attach to the fish, they invade under the skin, where they develop.
Ill fish are weakened, stay in the upper layers of water, weakly react to external stimuli. On the surface of the body and gills, a small white rash similar to semolina is noticeable. The diagnosis is made only after a microscopic examination of scrapings from the surface of the skin and gills, since a “white rash” can appear with some myxosporidioses, and also be a manifestation of the “mating outfit” of male carp in the spawning period.
The fight is complicated by the fact that the parasite is under the skin of the fish. Treatment is carried out only under the guidance of an ichthyopathologist. Prevention is to prevent weed fish from entering water bodies, pools, cages, where industrial cultivation is carried out. Transportation and transplantation of fish must be carried out using drugs such as malachite green, purple "K", the main bright green, potassium permanganate.
The causative agent of the disease is a cestode from the genus Triaenophorus. The development proceeds with the participation of two intermediate hosts: crustaceans and fish, mainly trout, perch, and a number of cyprinids. The main host is the pike. If there is both trout and pike in the reservoir, the occurrence of this disease becomes very likely. The management of fish farms, in which fishing is organized and in which trout is imported, needs to implement a set of measures to prevent this disease. The treatment of the disease has not been developed. In order to prevent fish disease in pond farms, it is necessary to protect ponds from penetration of pikes from sources of water supply.
With intensive infection, fish emaciation, bloating of the abdomen, pallor of the mucous membranes are observed. Among fry and yearlings death is noted.
Phylometroidosis is caused by roundworms - nematodes. The main host of the parasite is carp, the intermediate is cyclops. Female filometers reach a length of 90 - 160mm. They are localized in scaled pockets of carp in the head, pectoral fins, behind the gill covers. Males are much smaller than females; they are usually found in the walls of the swimming bladder.
When cleaning fish from female scales, the filometers look like pink-red rings with poor mobility. Although filometers are not dangerous to humans, their detection in fish causes a negative reaction in the person preparing the fish. The buyer usually returns such fish to sellers. The main cause of the disease is the transport of fish from dysfunctional fisheries to prosperous. Fish treatment is possible using a number of drugs with a high therapeutic effect.
Botriocephalosis is a helminthiasis disease in fish characterized by intestinal damage. Caused by tape helminth Bothriocephalus acheilognathi from this. Bothriocephalidae. Carp, carp, carp, bream, blue carp, grass carp, silver carp, roach, ide, barbel, catfish and others are sick, but the most susceptible are fry of carp, carp and grass carp, the infection of which reaches 80 - 100%. In this case, the mass death of juveniles occurs.
Botriocephalosis is widespread both in pond farms and in natural reservoirs. This is facilitated by the uncontrolled transport of fish, the availability of common sources of water supply, fish farming in head ponds, etc.
The juveniles and yearlings are most intensively infected in July - August, when zooplankton abundantly develops in ponds and the fish feed intensively.
Diplostomatosis is an invasive disease of fish caused by larvae of diagenetic flukes from the family Diplostomatidae, which are parasitic in the eyes of fish. Diplostomatosis is widespread among fish living in natural reservoirs. Young and adult fish are ill. Characteristic signs of the disease: lens opacification, throat formation, blindness. Occasionally, eyeballs are observed. The membranes of the eyes become inflamed, making blood circulation difficult, as a result, the lens is destroyed, the corneal tissue dies and ulcerates, and the lens falls out. In the affected areas of the eye, saprolegni mushrooms settle. Having lost his sight, the fish takes food poorly, loses weight, juveniles lag behind in growth. The causative agent of diplostomatosis develops with the help of two intermediate hosts: the first is a mollusk-pond, the second is fish. The main host is the piscivorous bird.
Postodiplostomosis is a common invasive fish disease, recorded both in natural reservoirs and in spawning-outgrowths and pond farms. It is characterized by damage to the skin, muscles, curvature of the spine. It is manifested by the appearance on the body of fish of black spots of various sizes, from where the disease got its original name - black-spotted disease. These spots are formed as a result of the deposition of black pigment in the habitats of helminth larvae.
The disease is recorded mainly in reservoirs in the southwestern regions of the country, where herons live more. Fish infection occurs mainly in the spring-summer period, which is associated with the development of the pathogen. Various types of freshwater fish are susceptible to post-diplostomosis - more than 60 species: carp, common carp, bream, roach, grass carp, silver carp, rudd, sabrefish, roach, ram, silver bream, perch, white-eye, chub, podust, etc. Most of these fish species have fishing value. The fry and fingerlings of these fish species are most sensitive to the disease. The body of the affected fry is deformed, the spine bends, flexibility is lost, growth is slowed down. Sick fish rise to the upper layers of the water, become weak and easy to catch. Black spots on the skin are formed in various places: on the fins, gills, tail, back, abdomen, sides, cornea of the eyes, on the mucous membrane of the oral cavity, etc. The number of such spots is several tens or even hundreds.
Sources of invasion - infected fish, mollusks and herons, invading ponds with helminth eggs.
Kaviosis is a helminth disease of carp, carp, and their hybrids, black and white cupids, characterized by intestinal damage. Called by the cestode Khawia sinensis from this. Caryophyllaidae.
The disease is recorded in all areas of carp farming. The disease affects all age groups of fish, but mostly yearlings and two-year-old carp in the spring and summer. In nature, in winter, the pathogen is stored in fish. Helminths are localized in the intestine and remain viable, and in the spring they begin to produce eggs. Cavia larvae remain in the body of intermediate hosts - oligochaetes, which also overwinter in water bodies. in the lower layer of soil. In the spring, with the filling of ponds with water, oligochaetes become active and rise into the upper soil layer. Fish, eating at the bottom of reservoirs, eat invasive oligochaetes and become infected with caviosis.
Symptoms Sick fish are inactive, their mobility is limited. they stay more in shallow water off the coast of the pond, their skin is dull. Fatness is reduced, exhaustion is noted. Gills and mucous membranes are anemic, bloating of the abdomen, redness of the anus is noted.
Argulosis affects most pond fish, especially juveniles, whose waste from argulosis take on a massive scale. The causative agent of the disease is the gill-tailed crustacean of the genus Argulus. Crustaceans have a rounded shape, their size is 4-8 mm. Parasitize on the surface of the body, piercing the skin of fish. At the wound site, inflammation usually develops, subsequently complicated by infection. Argulus can be seen with the naked eye. It looks like a rounded flat gelatinous body with a diameter of several millimeters, often moving. Two dark points are clearly visible - the faceted eyes of the crustacean. The disease is often observed in farms that organize amateur fishing and use wild fish (perch, bream, pike, roach, etc.) for stocking. Prevention is the most reliable way to prevent this disease. Effective treatment is possible only with the use of chlorophos, karbofos, organochlorine compounds, which have a negative effect on the reservoir.
Lerneosis is an invasive fish disease caused by parasitic crustaceans of the genus lernaca. It is observed when fish are grown in ponds and aquariums. The causative agent of lerneosis are l. cyprinacea and l. elegans, in herbivorous fish l. ctenopharingodnis, in animal-eaters - l. esocina. Crustaceans settle on the skin, fins, in the nasal fossa, eye hollows, mouth and gill cavities of fish.
With a population of 10-15 ind./p.z. cause anxiety of fish, increased mucilagination of integument, a bluish or gray coating appears on the body of fish. The diagnosis is made after microscopy of scrapings. Treatment is selected taking into account environmental conditions and the condition of the fish. There are several effective drugs, which include malachite green, brilliant green, purple "K", potassium permanganate, sodium chloride, formalin solution, etc.
Trichodinia, apiosis, boneosis, scyphidiosis, trichofriosis
Diseases are caused by parasitic ciliates, which develop on the surface of the body and gills in almost all cultivated fish species. With the number of 1-5 parasites in the field of view of the microscope (10x10), clinical signs of the disease are usually not manifested. With a population of 10-15 ind./p.z. cause anxiety of fish, increased mucilagination of integument, a bluish or gray coating appears on the body of fish. The diagnosis is made after microscopy of scrapings. Treatment is selected taking into account environmental conditions and the condition of the fish. There are several effective drugs, which include malachite green, brilliant green, purple "K", potassium permanganate, sodium chloride, formalin solution, etc.
In industrial aquaculture with the transition to high-intensity forms of fish farming (in cages, pools, etc.), nutritional diseases cause damage. They are divided into 2 groups. The first includes diseases associated with the use of unbalanced feed for fat, protein, carbohydrate, mineral and vitamin composition. The second group combines diseases that occur in fish as a result of consumption of poor-quality feed, seeded with microorganisms (bacteria or fungi), products of their vital activity or containing oxidized fats. Alimentary diseases are found in fish of different species and ages. They reduce the growth rate of fish and can cause their death. Features of their manifestation require not only general, but also special approaches to their prevention.
Ignoring issues related to fish diseases will sooner or later lead fish farming to big problems. In order to avoid them, it is necessary to organize regular ichthyopathological control over all technological operations, and especially for the transport of live fish.
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- I.N. Verbitskaya et al. Main diseases of pond fish. M., Kolos, 1972.- 72 p.
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