JPH07213234A - Preventive for parasitosis of cultured fishes or prevention thereof - Google Patents

Abstract

PURPOSE:To obtain the subject preventive containing an organoselenium compound-containing cell body as the active component and capable of being orally administrated without increasing, e.g. stress applied to cultured fishes. CONSTITUTION:This preventive for parasitosis of cultured fishes contains an orgnaoselenium compound-containing cell body (edible yeast, bacterium, fungus, unicellular green alga, etc.) as the active component. This preventive is administrated preferably in a stage from a fry to a young fish of the cultured fish and is useful for prevention of ectoparsitosis and improvement of growth rate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a preventive agent or preventive method for cultivated fish ectoparasites, which comprises an organized selenium-containing bacterium as an active ingredient.

[0002]

2. Description of the Related Art Damage caused by ectoparasites in farmed fish is particularly problematic mainly in seawater farmed fish.
It occurs in yellowtail, Thailand, flounder, puffer fish and amberjack, amberjack, etc., whose aquaculture amount has increased in recent years, and the damage to yellowtail and amberjack is particularly large. The main external ectoparasites are skin parasites, which are commonly called "Damushi", for example, Benedenia seriolae (Benedee).
nia seriolae), Benedenia hoshinai, Benedenia epinephere
heli), Neobenidenia SP (Neoben)
edenia sp. ), And a fish gill parasite known as Eramushi, Heteraxine heterocerca (He)
teraxine heterocerca), Zeuxapta japoni
ca) and Vivagina ta
i) are mentioned.

Mortality due to the infestation of ectoparasites is not so large, but when a large amount of parasites are parasitized, anorexia, growth inhibition, damage to the body surface and the like due to stress and the like are seriously impaired, and the bacterial value is impaired. It is considered to be a temporary factor in the epidemic of, and is a major problem. 1
The damage caused by external parasites that disappeared with the advent of TBTO (tributyltin oxide) organic tin-based fishing net antifouling agents from 967 to 1968 was discontinued from around 1986 when the use of organic tin compound-based fishing net antifouling agents was stopped. Immediately, the damage started to occur again. The control measures for these ectoparasitic diseases are basically to destroy the adult adults and the next-generation eggs (culture, 1991-).
5, P-66, Midori Shobo), as a means of adult control, freshwater bath, medicinal bath, and concentrated saltwater bath are reported (fish infectious diseases, published on May 10, 1984, P-468 to 469). , 47
2, Shuzo Egusa, Koseisha Koseikaku), but since the seawater in the small split cage is constantly exchanged with the surrounding seawater, it is necessary to take a huge amount of fish and store it in still water. In addition to giving a lot of stress to farmed fish, there are many problems in terms of extermination effect against ectoparasites and safety.

In addition, although oral administration agents such as biothionol type and organic phosphorus agents have been developed, there is a problem in terms of side effects on cultured fish and none have been put into practical use.

Further, as measures against ectoparasite diseases of seawater-cultured fish, fresh water baths and concentrated salt water baths have been used for a long time.
Although various drugs have been tried to be used in the medicinal bath method,
There are many problems in terms of anthelmintic effect or safety in fish and the environment. For example, there is a method using alkaline peroxide, but it is limited due to its strong influence on fish.

Recently, a drug application method using a hydrogen peroxide agent has been developed for ectoparasitic diseases of seawater-cultured fish (JP-A-1-31).
7346). This drug can be used by diluting it with seawater, and has the convenience that it is not necessary to transport fresh water to near the cage. However, hydrogen peroxide bath (medicine bath for 3 minutes) must be performed in a special tank as well as the fresh water bath that has been generally performed, which reduces stress on fish, adverse effects of chemicals on body surface, Has shown little reduction in labor for aquaculture operators.

The laying of these ectoparasites tends to be entangled in the cage nets and the like by the egg thread, and the degree thereof increases as the number of organisms attached to the net increases, resulting in the inflow of hatching larvae into the small splits. , Increase parasitics. Since the use of organotin compound-based anti-fouling agents for fishing nets was stopped, new materials such as organic nitrogen-sulfur and copper were developed, but they were not found to be effective against parasite eggs. However, for the purpose of removing adhering organisms from the net cage, there is no countermeasure other than frequent replacement of the cage net even after spending a great deal of labor of the aquaculture operator, and it causes a lot of artificial stress to the fish. Become.

[0008]

[Problems to be Solved by the Invention] At present, a freshwater bath, which has been known for a long time, is used as a control measure for seawater-cultured fish parasites. As a method therefor, a large amount of freshwater is prepared for ships and offshore facilities. Then, the cultured fish is taken out from the cage and immersed in the fresh water for 3 to 6 minutes to inactivate the parasites by the osmotic pressure of the fresh water, causing the parasites to fall off or die from the fish body.

[0009] However, when a large amount of fresh water is treated, it takes more labor than necessary, and in order to handle the cultured fish with a net or the like and to expose the cultured fish to physiologically abnormal conditions of fresh water, the cultured fish must be treated. On the other hand, it has the drawback of artificially applying a great deal of stress. Moreover, not only parasites that parasitize fish bodies, but also measures against parasite eggs are important,
As a countermeasure against this egg, it is necessary to change the net every certain period,
It requires a great deal of effort for the aquaculture operator and also puts great stress on the aquaculture fish. Diseases caused by ectoparasites are not a serious problem if the number of parasites is small, but they become a problem when the number of parasites is large and damage to the body surface becomes conspicuous. Also, the resistance to parasites increases during the adult season, and the cultured fish themselves remove the parasites that adhere to the body, so this is not a serious problem, but the resistance to parasites is weak and the adherent parasites are removed. This is a particular problem during the fry and juvenile seasons when it is not possible.

On the other hand, the zinc-coated wire net cage has a good net shape and good water permeability, and since the surface of the iron wire in the wire net is smooth, the number of eggs attached is extremely small and it is remarkable for the control of ectoparasites. It is effective. However, the service life is shorter than that of synthetic fiber nets, and during the juvenile and juvenile stages when the fish size is particularly small, which is a problem, it is necessary to have a wire net cage that matches the fish size, but the tide flow will deteriorate. The problem is that the service life will be even shorter and the price will be much higher than that of synthetic fiber nets. In addition, in order to control bacterial diseases that develop during the juvenile and juvenile stages, wire mesh cages are often used from the latter half of the juvenile season from the viewpoint of managing cultured fish. The effect of was drastically reduced.

Therefore, as a measure against the ectoparasitic disease of the above-mentioned cultured fish, stress exerted on the cultured fish is reduced as much as possible, labor of the aquaculture operators is reduced, and effective preventive effect is obtained by oral administration. There has been a demand for the development of preventive agents or preventive methods having

[0012]

[Means for Solving the Problems] The physiological role of selenium on cultured fish has not been studied at all, and there is almost no report on its necessity. In addition to the minerals in the feed, the cultured fish absorb inorganic salts dissolved in environmental water directly into the body through the gills, skin and intestinal tract. In fact, 0.2 ppb as selenium in the form of selenite ion in clean seawater.
The content of selenium in the muscles of 52 species of fish, which are contained in a small amount and have grown in a clean environment, has an average of less than 1 ppm in terms of wet weight (Fisheries Science Series (47) “Metabolism of Fish”, 118 to 119, Published October 15, 1983,
There is a Seiseisha Koseikaku). However, there is known a feed for aquaculture of minerals, which is obtained by adding 0.1 to 1 ppm of inorganic selenium to a feed for aquaculture (Japanese Patent Laid-Open No. 61-146155).
As described in the examples described later), inorganic selenium did not have any preventive effect on ectoparasite disease of cultured fish.

Under these circumstances, the present inventors have conducted diligent research aiming at the development of a preventive agent or a preventive method effective for the prevention of cultivated fish ectoparasite diseases, and as a result, the inventors have found that it contains organic selenium. The present invention was confirmed by confirming the novel fact that prevention of cultivated fish ectoparasiticosis is possible even by oral administration by feeding the cultured cells to those cultured fish, particularly preferably from the juvenile stage to the juvenile stage. It came to completion.

That is, the present invention provides a preventive agent for cultivated fish ectoparasites, which comprises an organized selenium-containing bacterium as an active ingredient, or an administered selenium-containing bacterium is administered to a cultured fish. It is a preventive method against insect disease. First, examples of the organic selenium in the present invention include organic selenium such as selenomethionine and selenocysteine. The organic selenium-containing bacterium in the present invention may be any organic selenium-containing bacterium containing these organic selenium in the form of a high molecular weight polypeptide or protein.

As the organic selenium-containing cells, various known organic selenium-containing cells can be used. For example, a method for producing a microorganism containing a large amount of organic selenium by culturing microorganisms such as mold, yeast, bacteria, actinomycetes in a culture solution containing a selenium compound such as selenium dioxide (JP-A-53-53).
No. 148587), a selenium-containing selenium protein polysaccharide SE having a molecular weight of 10,000 or more from selenium-containing Saccharomyces yeast cells obtained by culturing in a medium containing a selenium compound.
A production method for obtaining PS (Japanese Patent Application Laid-Open No. 57-174098) and the like are exemplified, but yeast, bacteria, fungi, single-cell green algae and the like are preferably used to obtain bacterial cells at a biological cell concentration of biological space or more. To obtain a microbial cell in which a high molecular weight organized selenium bound to a polypeptide or protein is accumulated by dispersing it in a medium containing inorganic selenium such as selenium dioxide or selenious acid (Japanese Patent Laid-Open No. 4-42 408
The bacterial cells obtained according to Japanese Patent Laid-Open No. 88) are inexpensive and preferred.

[0016] As these organized selenium-containing cells,
Examples include edible yeasts, bacteria, molds or unicellular green algae, or disrupted cells thereof. Suitably edible yeasts such as Saccharomyces
Yers), Torula supor
a) genus, Torulopsis genus, Mycotorula genus, Candida genus, Hansenula (Hansenul)
a) Yeast belonging to the genus, particularly preferably bacterial cells belonging to the genus Saccharomyces, and generally, as a selenium content per 1 g of dried bacterial cells, for example, 100 to 8000 ppm, preferably 500 to 5000 ppm, preferably 1000 to 3
Bacteria of 000 ppm may be used.

In the production of the preventive agent for cultivated fish ectoparasites of the present invention, the organized selenium-containing bacterium may be used as it is or as a non-toxic carrier for cultured fish, or an appropriate stabilizer may be added to prepare a compounding agent for fish. The shape may be adjusted to an appropriate state such as powder, dry pellets or moist pellets. When administering the preventive agent for cultivated fish ectoparasites of the present invention, it may be administered alone to the fish, but it may be fed as a mixture with a fish feed containing a non-toxic simple substance for cultured fish. It is simple and preferable. The non-toxic carrier for cultured fish, for example, calcium carbonate, calcium phosphate, calcium sulfate, wheat flour, starch, dextrin, feed yeast and feed raw material grains,
It may be used by diluting it by mixing it with algae or lees, or by adding it to a premix of vitamins, minerals or the like, or a fish feed containing these premixes. In the case of raw bait, additives such as sodium alginate and guar gum may be used at the same time. Usually, cultured fish targeted by the present invention by being added to raw feed or mixed feed,
For example, a method of feeding to seawater-cultured fish such as yellowtail, amberjack, flatfish, Thailand, flounder, and puffer fish is preferable.

In the preventive agent for cultivated fish ectoparasite disease thus adjusted, the dose of selenium derived from the organized selenium-containing microbial cells varies depending on the type and size of the fish.
Usually 0.001 mg / kg of fish body weight per day
50 mg, preferably 0.01 mg to 10 mg is exemplified. The calculation of the dose of selenium per fish weight is a conversion of the amount directly ingested by the cultured fish in the cage,
Further, for example, when the preventive agent is mixed with a fish feed, the concentration of selenium derived from the organic selenium-containing bacterium added is about 0.05 to 50 ppm, preferably 0.1 to 10 ppm. It is preferable.

Regarding the timing of administration of the preventive agent for cultivated fish ectoparasites of the present invention, for the purpose of prevention, the above-mentioned Benedenia seriolae is used.
e), Benedenia h.
oshinai), Benedenia Epineferi (Ben
edenia epinepheli, Neobenedenia sp., Heteraxine heteroselka (Heteraxine h)
Eterocerca), Zeuxapta japonica, Vivagina
Administration is started before ectoparasite flukes such as Thailand (Bivagina tai) are infested, and the first half of the aquaculture where the damage is most severe, that is, large fish such as yellowtail, amberjack and flatfish, are collected after hatching in natural waters. From the juvenile stage to the juvenile period (about 600 g to 800 g of juvenile fish weight) as aquacultured fish obtained by
It is preferable to administer a single dose, and similarly, for small- to medium-sized fish such as puffer fish and tie, it may be administered once to three times a day from the juvenile stage to the juvenile stage.

Further, once cultured cultivated fish having ectoparasites are treated to remove the ectoparasites by a means such as a fresh water bath, the organoselenium-containing bacterium of the present invention is described above. When used in the same manner as described above, a preventive effect against cultured fish ectoparasite disease can be effectively expressed.

[0021]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto.

[0022]

[Reference Example 1] Preparation of organized selenium-containing bacterium (Saccharomyces cerevisiae) YPG medium adjusted to pH 5 (glucose 0.5%, potassium phosphate 0.5%, magnesium sulfate 0.2%) 1
Dispense 00 ml into a 500 ml Erlenmeyer flask and remove 121
After sterilization at 15 ° C for 15 minutes, Saccharomyces cerevisiae FTY-3 (manufactured by Asahi Kasei Kogyo Co., Ltd., trade name; 45FC
(1 yeast) was inoculated with 1 platinum loop and shake-cultured at 30 ° C. for 24 hours to give an inoculum.

Molasses medium (10% molasses (containing 4% as sucrose), 0.5% urea), 75%, which was sterilized by heating at 120 ° C. for 30 minutes using four 30 L jar fermenters Phosphoric acid 0.1%, zinc sulfate 0.0
003%) 20 L, 500 ml of the above inoculum culture solution
(100 ml x 5) is planted in each jar fermenter, 32 ° C, aeration rate 30 L / min, stirring speed 300
Incubated at rpm for 16 hours.

Then, the cells were collected by using a continuous centrifuge, about 20 L of water was added to suspend the cells, and the cells were washed by centrifugation. After repeating this operation three times, the bacterial cell concentration was adjusted to 2.5 × 10 ⁹ cells / ml so that the bacterial cell concentration was higher than the biological space, and 0.03 M phosphoric acid containing 0.5% glucose was added. Suspend in 5 L of buffer solution (pH 5),
0.4 g of selenious acid (48 ppm as the selenium concentration) was added, and the reaction was carried out at an air flow rate of 10 L / min, a stirring speed of 200 rpm, and a shaking (reaction) temperature of 30 ° C. After 18 hours, the cells were collected by centrifugation and further washed with 20 L of water three times to obtain 3.5 kg of wet cells. Then, add 7 L of water and stir,
After the dispersion, the mixture was heated at 90 ° C. for 15 minutes and was then spray-dried to obtain 1.1 Kg of dry powder (water content 4.
1%, intracellular selenium concentration in selenium 1910
ppm).

For the measurement of selenium, dried bacterial cells were oxidatively decomposed with nitric acid and perchloric acid, and this decomposed liquid was measured by a fluorometric method using 2,3-diaminonaphthalene.

[0026]

[Reference Example 2] Organized selenium in cells containing organic selenium 5 g of the cells obtained in Reference Example 1 were suspended in 50 ml of water,
After adjusting the pH to 7 with 1N caustic soda, the cells were crushed with a Positron crusher and further heated at 95 ° C for 10 minutes,
Centrifuge at 10,000 rpm for 15 minutes, 38 ml of supernatant
Was obtained (selenium concentration 174 ppm). 10 ml of the supernatant was freeze-dried and then dissolved in 2 ml of water, and 1 ml of the solution was used to separate a 100 ml column of Sephadex G50 (2 x 3
2 cm) and the distribution of the organic selenium and the protein were examined, and FIG. 1 (in the figure, the solid line is the value of the protein content in each elution fraction measured by absorbance at 280 nm, and the broken line is the selenium content in each elution fraction). The content means the value measured in the same manner as in Reference Example 1).
It was shown to. As a result, 85% or more of selenium was present in the high molecular weight fraction showing protein.

[0027]

Reference Example 3 Preparation of Organized Selenium-Containing Bacteria (Bacillus subtilis) Meat Extract 1.0% by Weight, Peptone 1.0% by Weight, NaC
1 L of each medium was prepared by adding 5 ppm of selenium dioxide to the medium containing 0.5% by weight. Bacillus subtilis IFO3, which had been transferred to a 2 L capacity mini jar fermenter and pre-cultured after sterilization
10 ml of 007 was inoculated into a mini jar fermenter and shake-cultured for 30 hours. After completion of the culture, the bacterial cells were collected from the culture solution by centrifugation and washed twice with about 1 L of water. Furthermore, in order to completely remove contaminants attached to the cells, the cells were washed 4 times with about 2 L of water.

[0028]

Example 1 Effect of feeding selenium-containing substance to amberjack 200 amberjack with a body weight of about 50 g were set as one group, and three groups were prepared in total. Organized selenium prepared in accordance with Reference Example 1 using Saccharomyces cerevisiae containing selenium (selenium concentration; 1910 ppm / dried cells) (feed 1 ward), selenium dioxide of Reference Example 3 and Bacillus subtilis IFO3007 Selenium-containing Bacillus subtilis (selenium concentration; 2100 ppm / dried cells) (feed group 2) and sodium selenite (control group) as inorganic selenium as selenium concentration 0.3 ppm (fish weight 1
A selenium dose of 0.1 mg per Kg) was added to and mixed with the raw sardine diet for adjustment.

First, a fresh water bath is applied to the test fish in advance, and Neobenede SP is used.
nia sp. ) And Zeuxapta japonica (Z
After confirming that there is no infestation of euxapta japonica), each of the adjusted feeds is
I paid for 0 days. The control group was fed with a feed as a non-administered group of selenium-containing cells (non-administered group). At the end of the salary, 20 test fish were randomly picked from each test plot, and the average weight and growth rate of the test fish in each test plot were calculated.

Further, Neobenedenia parasitized per test fish
sp. ) And Zeuxapta japonica (Zeuxa)
The average number of parasites of Pta japonica) was measured and Table 1
It was shown to. The selenium concentration in the live sardine feed used was 0.48 ppm, and the same selenium was used below.

[0031]

[Table 1]

As shown in Table 1 above, Neobenedenia sp.
sp. ) And Zeuxapta Japonica (Zeux)
The average number of parasitics of Apta japonica) is 126
There are 21 animals, whereas 16 animals in the Saccharomyces cerevisiae feeding area containing organic selenium in the 1st feed group.
Bacillus containing organic selenium from the 2nd feed
In the subtilis feeding area, there were 21 and 8 animals, and the number of ectoparasite parasites was extremely reduced by the administration of organic selenium, and the preventive effect of the ectoparasite disease was recognized, and it was effective as an ectoparasite preventive agent. Was shown.

Further, the growth rate of the test fish was good by the administration of organized selenium. On the other hand, in the control group of the inorganic selenium (sodium selenite) feed group, Neobenedenia sp. And Zeuxapta japonica (Zeuxapta japonica) were used.
The average number of parasites of P. nica was 135 and 20, and no ectoparasite parasitic prevention was observed, and the growth rate was also reduced. Although sardine contained 0.48 ppm of selenium in the raw sardine, no ectoparasite-preventing effect was observed. From the above, it was judged that only organic selenium-containing cells were effective. It was

[0034]

[Example 2] A dose of organizing selenium-containing Saccharomyces cerevisiae for amberjack 200 amberjack with a body weight of about 50 g was prepared as one group, and 4 groups were prepared in total. Reference example 1
Organized selenium-containing Saccharomyces cerevisiae (selenium concentration; 1910 ppm / dry microbial cell) was added to and mixed with sardine live feed so that the selenium concentration was 0.1 ppm, 1.0 ppm, and 10 ppm.

A fresh water bath is performed on the test fish in advance,
Neobenedenia
sp. ) And Zeuxapta Japonica (Zeux)
After confirming that there is no infestation of Apta japonica), each adjusted feed was fed for 30 days in a small split cage. The sardine live feed containing no organized selenium-containing cells was used as a control with a selenium addition concentration of 0 ppm. At the end of salary, 20 test fish randomly from each test area
The tail was picked up, and the average weight and growth rate of the test fish in each test section were obtained.

Further, Neobenedenia parasitized per test fish
sp. ) And Zeuxapta japonica (Zeuxa)
The average number of parasites of Pta japonica) was measured and Table 2
It was shown to.

[0037]

[Table 2]

As shown in Table 2 above, compared to the control group, Neobenedenia s was fed by feeding Saccharomyces cerevisiae containing organic selenium (hereinafter referred to as organic selenium containing yeast).
p. ) And Zeuxapta japonica (Zeuxap)
A decrease in the number of parasites of ta japonica) was observed.
Moreover, the growth rate of the test fish was also good by the administration of the cells containing the organized selenium. Based on this, the concentration of selenium derived from cells containing organized selenium in the fish feed is 0.05 ppm.
As described above, preferably 0.1 ppm or more is contained, and it is possible to contain up to the maximum amount that does not cause toxicity, and in view of economic effect, preferably 50 ppm or less,
It is particularly preferably 10 ppm or less.

[0039]

Example 3 Organized Selenium-Containing Yeast Feeding Test for Hamachi in the Field-1 Total of 5,000 hamachi with a body weight of about 50 g as one group 2
I prepared a ward. The organized selenium-containing yeast of Reference Example 1 (selenium concentration; 1910 ppm / dried cells) was added to and mixed with a raw sardine diet so that the selenium concentration was 0.3 ppm. A fresh water bath was performed on the test fish in advance, and the Benedenia.seroio was used.
lae) and Heteraxine heteroselka (Hete)
racine. After confirming that there was no infestation of (heterocerca), each adjusted feed was fed for about 2 months in a small split cage.

The control group was fed with a feed containing no organized yeast containing organic selenium. Fifty test fish were randomly picked from each test plot every month after the start of feeding, and the average weight and growth rate of the test fish in each test plot were determined. Furthermore, Benedenia seriolae (Bene) parasitizing one fish under test
denia. seriolae) and heteraxine
Heteroselka (Heteraxine.heteroc)
The average number of parasitics of erca) was measured and shown in Table 3.

[0041]

[Table 3]

As shown in Table 3 above, Benedenia seriola in the control area was used.
e) and Heteraxine heterocerca (Hetera)
xine. Heterocerca) The average number of parasites was 68, 11 and 154 on the 30th and 60th days, respectively.
The number of animals is 24, whereas the number of organs containing selenium-containing yeast is 14, 30 on the 30th day and 32 on the 60th day.
The number of mice was 9, and it was suggested that the prevention of ectoparasite parasitism by feeding yeast containing organic selenium against yellowtail. No abnormalities were found in the test fish during the test period.

[0043]

Example 4 Organized Selenium-Containing Yeast Feeding Test for Hamachi in the Field-2 Two cages were prepared in which 10,000 juvenile yellowtail fish with an average body weight of about 50 g were released. Under the same test conditions as in Example 3, the organized selenium-containing yeast feeding test was carried out. Two
During the test period of one month, it was determined that ectoparasites were infected by visual observation during an appropriate period. If the average number of parasites was 50 or more, a fresh water bath or hydrogen peroxide bath was performed , The average number of parasites is less than 50, this 2
The number of times a fresh water bath or a hydrogen peroxide bath was carried out to maintain the average number of parasites of 50 or less per month was investigated and shown in Table 4.

[0044]

[Table 4]

As shown in Table 4 above, in the control group, in order to maintain the average number of ectoparasites to be 50 or less, three fresh water baths and two hydrogen peroxide baths were required. In the case of feeding yeast containing organic selenium, the frequency of fresh water bath and hydrogen peroxide bath was remarkably reduced, suggesting the effect of preventing parasitism of ectoparasites, and the labor of aquaculture operators was reduced.

[0046]

Example 5 Organized Selenium-Containing Yeast Feeding Test for Amberjack in the Field-1 Two aquariums were prepared in which 5,000 juvenile amberjack larvae with an average body weight of about 60 g were released. Organized selenium-containing yeast of Reference Example 1 (selenium concentration; 1910 ppm /
Dried sardines) live sardine [Vitamin premix at a ratio of 2% (Mitaka Pharmaceutical Co., Ltd., trade name; Hamachi hit.
M) was mixed and fed so as to have a selenium concentration of 1.0 ppm. The control group was also fed under the same conditions without adding the organic selenium-containing yeast.

During the feeding period of about 2 months, a total of 51 feedings were performed, and 50 fish were randomly picked from each ward every month, and Neobenedenia sp. And parasites per fish tested were parasitized. Zeuxapta japo
The average number of parasites in Nica) was investigated and is shown in Table 5.

[0048]

[Table 5]

As shown in Table 5 above, Neobenedenia sp.
p. ) And Zeuxapta japonica (Zeuxap)
ta japonica) has an average parasitic number of 3
On day 0, there are 93, 18 and on day 60, there are 225 and 34, whereas in the organic selenium-containing yeast feeding area,
After 30 days, the number was 20, 6 and at 60 days, the number was 33 and 13 and the effect of ectoparasites on the amberjack by feeding the yeast containing organic selenium was suggested.

Further, the body color of the test fish in the yeast-containing area containing organized selenium is green brown, which is the same as the natural amberjack body color,
It had a clear yellow belt on the body side. During the test period,
No abnormalities were found in the test fish after the end of the period.

[0051]

[Example 6] Organized selenium-containing yeast feeding test for amberjack in the field-2 Two cages were prepared in which 10,000 amberjack juveniles with an average weight of about 80 g were released. Organized selenium-containing yeast (selenium concentration; 1910 ppm / dried cells) was added to the test plot in a raw sardine diet [vitamin premix at a ratio of 2% (vitamin premix (Mitaka Pharmaceutical Co., Ltd., trade name;
Hamachi hit / M) was mixed to give a selenium concentration of 0.3 ppm. The control group was also fed under the same conditions without adding the organic selenium-containing yeast.

A total of 62 feedings were carried out for a feeding period of about 2.5 months. During the test period, it was judged that ectoparasites were infected by visual observation during an appropriate period, and when the average number of parasites was 50 or more, a fresh water bath or hydrogen peroxide bath was performed to determine the average parasites. The number of freshwater baths or hydrogen peroxide baths to maintain the average number of infestations of 50 or less in the last two months was investigated by setting the number to 50 or less and Table 6
It was shown to.

[0053]

[Table 6]

As shown in Table 6 above, the number of times the fresh water bath and the hydrogen peroxide bath were carried out was remarkably reduced by feeding the organizing selenium-containing yeast, suggesting the effect of preventing ectoparasite parasitism.
In addition, as in Example 5, the body color of the test fish in the organic selenium-containing yeast feeding section was the same as the natural amberjack body color.
During the test period, no abnormalities were found in the test fish after the end of the period.

[0055]

INDUSTRIAL APPLICABILITY By the preventive agent for cultivated fish ectoparasites of the present invention or a method for preventing the same, it is possible to prevent ectoparasitic diseases, particularly, to prevent the infection of the cultivated fish. The rate can be improved.

[Brief description of drawings]

FIG. 1 is a distribution diagram of the organized selenium in the protein fraction in the organized selenium-containing cells obtained in Reference Example 1.

Claims (17)

[Claims] 1. A preventive agent for cultivated fish ectoparasites, comprising an organized selenium-containing bacterium as an active ingredient. 2. The preventive agent for cultivated fish ectoparasitic diseases according to claim 1, wherein the organized selenium-containing bacterium is an edible yeast, bacterium, mold or unicellular green alga. 3. The edible yeast is Saccharomyces (S
genus accharomyces, Torulaspora (Tor)
ulasupora, Torulopsis (Torulo)
psis genus, Mycotorula
A yeast belonging to the genus, the genus Candida, and the genus Hansenula.
The aquatic fish ectoparasite disease preventive agent described. 4. The preventive agent for cultivated ectoparasite diseases according to claim 1, wherein the cultivated fish is seawater cultivated fish. 5. The preventive agent for cultivated fish ectoparasite according to claim 4, wherein the seawater-cultured fish is yellowtail, amberjack, flatfish, thailand, flounder, puffer fish or its juvenile to juvenile stage. 6. The parasite is Benedenia seriolae (B
enedenia seriolae, Benedenia hoshinai, Benedenia epinepheri
nepheli), Neo-Benidenia SP (Neo)
bendenia sp. ), Heteraxine heterocerc
a), Zeuxapta (Zeuxapta)
japonica and Vivagina Thai (Bivag)
ina tai) 1 or 2 selected from the group consisting of
2. The preventive agent for cultivated fish ectoparasite diseases according to claim 1, which comprises more than one species. 7. The preventive agent for cultivated fish ectoparasitic diseases according to claim 1, wherein the preventive agent contains organized selenium-containing cells and a non-toxic carrier for cultured fish. 8. A non-toxic carrier for cultured fish is calcium carbonate, calcium phosphate, calcium sulfate, wheat flour, starch, dextrin, feed yeast, feed raw grains,
The preventive agent for cultivated fish ectoparasites according to claim 7, which is one or more selected from the group consisting of algae and lees. 9. The preventive agent for cultivated fish ectoparasite disease according to claim 1, wherein the preventive agent is a preventive agent for infection of parasites. 10. A method for preventing ectoparasite diseases in cultured fish, which comprises administering organized selenium-containing cells to the cultured fish. 11. The method for preventing ectoparasite diseases of cultured fish according to claim 10, wherein the organized selenium-containing bacterium is an edible yeast, bacterium, mold or unicellular green alga. 12. The edible yeast is Torulaspora (T), which belongs to the genus Saccharomyces.
genus orulaspora, Torrupsis (Toru)
genus Lopsis, Mycotorula
The method for preventing ectoparasite diseases of cultured fish according to claim 11, which is a yeast belonging to the genus a), the genus Candida, and the genus Hansenula. 13. The method for preventing ectoparasite disease of cultured fish according to claim 10, wherein the cultured fish is seawater cultured fish. 14. The method for preventing ectoparasite disease of cultured fish according to claim 13, wherein the seawater-cultured fish is a yellowtail, amberjack, amberjack, thailand, flounder, puffer fish or its juvenile to juvenile stages. 15. The parasite is Benedenia seriolae or Benedenia hoshina.
i), Benedenia
epinepheli), Neobenedenia sp., Heteraxine heterocella
cerca), Zeuxapta japonica (Zeuxa)
pta japonica) and Vivagina Thai (B
The method for preventing cultivated fish ectoparasite diseases according to claim 10, which is one kind or two or more kinds selected from the group consisting of ivagina tai). 16. The method for preventing cultured ectoparasite diseases according to claim 10, wherein the administration method is an oral administration method. 17. The method for preventing ectoparasite disease of cultured fish according to claim 10, wherein the preventive method is a method for preventing parasitic infection.