JP7526770B2 - Oral anthelmintic composition for pufferfish, oral composition for preventing emaciation disease for pufferfish, and myxosporean anthelmintic method and method for preventing emaciation disease in pufferfish using the same - Google Patents

Description

The present invention relates to an oral anthelmintic composition for pufferfish, an oral composition for preventing emaciation disease for pufferfish, and an improved method for anthelminticating myxosporean parasites in pufferfish and a method for preventing emaciation disease in pufferfish using the same.

Myxosporea are microscopic parasites that belong to the class Myxosporea in the phylum Cnidaria and have a complex life cycle that alternates between two hosts, aquatic invertebrates and vertebrates. Many species are known to have serious industrial impacts on fish, particularly farmed fish, and specific examples include the bivalve genera Ceratomyxa (earthworms), Chloromyxum (single-striped beetles), Enteromyxum (striped beetles), Henneguya (rotary fans), Hoferellus (striped beetles), Myxidium (weave beetles), Myxobolus (striped beetles), Sphaerospora (striped beetles), Thelohanellus (striped beetles), and the multivalve genus Kudoa.

In Japan, one well-known infectious disease in farmed fish caused by myxosporean parasites is emaciation disease (myxosporean emaciation disease), which has been identified in farmed tiger pufferfish in the Kyushu region since around the 1990s (see Non-Patent Document 1). Affected fish become so emaciated that their skulls protrude and their eyes become sunken, and eventually die. The causative agent, myxosporean parasites the intestines, causing pathological changes characterized by proliferation and exfoliation of intestinal epithelial tissue. This is thought to result in impaired nutrient absorption and osmotic pressure regulation, leading to emaciation.

The pathogens of emaciation disease in tiger pufferfish were found in the intestinal epithelium of diseased fish, and a new species of myxosporean, Leptotheca fugu, and an unidentified species, Myxidium sp., were found. However, based on the results of subsequent genetic analysis of the 18S ribosomal RNA gene, the former was reclassified as Sphaerospora, and the latter was identified as Enteromyxum leei. Enteromyxum leei has also been found in various farmed fish and aquarium fish, such as gilthead seabream in Cyprus and turbot in Korea, and infection has been reported in over 50 species of marine fish. As mentioned above, it is believed that the life cycle involves alternate hosts, but because trophozoites before sporulation are transmitted directly from fish to fish, the disease can spread rapidly within farms, easily causing damage to spread.

Currently, there is no established treatment or control method for emaciation disease in tiger pufferfish and other fish belonging to the pufferfish family, and the only effective way to prevent the spread of infection is to conduct PCR or other tests when introducing seedlings and intermediate fish and to avoid introducing infected fish into the breeding environment.

Regarding the use of drugs to eradicate myxosporean parasites, the use of a combination of sodium salinomycin and amprolium (70 mg and 100 mg per kg of fish body weight, respectively) as an anthelmintic for Enteromyxum leei in European sea bream has been reported (see Non-Patent Document 2). According to this report, when diseased fish were reared in a hygienic environment (21°C) and the above-mentioned doses were administered, normal cysts disappeared in about six weeks.

It has also been reported that treatment of several fish species kept in aquariums in the United States with a combination of salinomycin sodium and amprolium (70 mg/kg of fish body weight and 100 mg/kg of fish body weight, respectively) by oral administration reduced mortality and improved clinical symptoms (see Non-Patent Document 3).

Tetsuya Yanagida, "Myxosporean emaciation disease," Fish Pathology, Vol. 52, No. 2, 2017, pp. 63-67 E. Golomazou et al. The Israeli Journal of Aquaculture - Bamidgeh, 58(3), 2006, 157-169. URI: http://hdl.handle.net/10524/19172 Michael W Hyatt et al. Diseases of Aquatic Organanisms, 2018 Dec 11; 132(1): 37-48. doi: 10.3354/dao03303.

In fish that have developed emaciation disease due to infestation with myxosporean parasites, the efficiency of nutrient absorption is reduced due to the detachment of intestinal epithelial tissue, and even if deworming after the onset is successful, the growth of the fish is subsequently impaired, resulting in problems of reduced yield and reduced commercial value in the case of farmed fish. However, there is currently no established method for preventing infestation with myxosporean parasites that cause emaciation disease. Furthermore, there is currently no established method for either deworming the parasites that cause emaciation disease in fish belonging to the Tetraodontiidae family, including tiger pufferfish, or for preventing infestation with the parasites that cause emaciation disease in fish belonging to the Tetraodontiidae family. The combination of salinomycin sodium and amprodium described in Non-Patent Documents 2 and 3 has not been confirmed to be suitable for fish belonging to the Tetraodontiidae family, and the dosage per unit fish weight (70 mg and 100 mg per kg of fish weight, respectively) is high, so if it is mixed with feed and administered in an open water system such as an aquaculture tank, it may cause a decrease in feeding rate and a corresponding decrease in administration efficiency.

The present invention has been made in consideration of such circumstances, and has as its object to provide an oral anthelmintic composition for pufferfish, an oral composition for preventing emaciation disease for pufferfish, and a method for anthelminticing myxosporean parasites in pufferfish and a method for preventing emaciation disease in pufferfish using these.

In accordance with the above-mentioned objective, the first aspect of the present invention solves the above-mentioned problems by providing an oral anthelmintic composition for pufferfish that contains only salinomycin, a medicamentously acceptable salt thereof, or a mixture thereof as an active ingredient and is used to eliminate one or both of Enteromyxum leei and Sphaerospora fugu that are parasitic in fish belonging to the Tetraodontiformes and Tetraodontidae families.

The oral anthelmintic composition for pufferfish according to the first aspect of the present invention is preferably intended for oral administration to the fish belonging to the Tetraodontiformes and Tetraodontidae family so that the daily dose of the active ingredient is 0.5 to 10 mg per kg of fish body weight.

The oral anthelmintic composition for pufferfish according to the first aspect of the present invention may be one for orally administering to fish belonging to the order Tetraodontiformes and family Tetraodontidae such that the single dose of the active ingredient is 1 to 10 mg per kg of fish body weight.

The oral anthelmintic composition for pufferfish according to the first aspect of the present invention is preferably intended for oral administration to said fish belonging to the order Tetraodontiformes and family Tetraodontidae at administration intervals of 12 hours or more and 72 days or less.

The oral anthelmintic composition for pufferfish according to the first aspect of the present invention is preferably intended for oral administration to said fish belonging to the order Tetraodontiformes and family Tetraodontidae not more than once per day, and not less than four and not more than seven times per week.

The second aspect of the present invention solves the above problems by providing an oral composition for preventing emaciation disease in pufferfish, which contains only salinomycin, a medicamentously acceptable salt thereof, or a mixture thereof as an active ingredient, and which prevents parasitism of one or both of Enteromyxum leei and Sphaerospora fugu in fish belonging to the Tetraodontiformes and Tetraodontidae families.

The oral composition for preventing emaciation disease in pufferfish according to the second aspect of the present invention is preferably intended for oral administration to the fish belonging to the order Tetraodontiformes and family Tetraodontiidae so that the daily dose of the active ingredient is 0.5 to 5 mg per kg of fish body weight.

The oral composition for preventing emaciation disease in pufferfish according to the second aspect of the present invention may be one for orally administering to fish belonging to the order Tetraodontiformes and family Tetraodontiidae such that the single dose of the active ingredient is 1 to 5 mg per kg of fish body weight.

The oral composition for preventing emaciation disease in pufferfish according to the second aspect of the present invention is preferably intended for oral administration to the fish belonging to the order Tetraodontiformes and family Tetraodontiidae at administration intervals of 12 hours or more and 72 days or less.

The oral composition for preventing emaciation disease for Tetraodontiformes fish according to the second aspect of the present invention is preferably intended for oral administration to said fish belonging to the Tetraodontiformes and Tetraodontidae family not more than once per day and not less than four and not more than seven times per week.

A third aspect of the present invention solves the above-mentioned problems by providing a method for exterminating one or both of Enteromyxum leei and Sphaerospora fugu parasitizing fish belonging to the order Tetraodontiformes and family Tetraodontidae, which comprises a step of orally administering to said fish belonging to the order Tetraodontiformes and family Tetraodontidae an oral composition containing salinomycin or a medicamentously acceptable salt thereof alone as an active ingredient such that the daily dosage of the active ingredient is 0.5 to 10 mg per kg of fish body weight .

In the method for anthelmintic fish of the pufferfish family according to the third aspect of the present invention, the amount of the active ingredient administered per time is preferably 1 to 10 mg per kg of fish body weight.

In the method for anthelmintic myxosporean parasites for pufferfish according to the third aspect of the present invention, the oral composition is preferably administered at intervals of 12 hours or more and 72 days or less.

In the myxosporean anthelmintic method for pufferfish according to the third aspect of the present invention, it is preferred that the number of administrations per day does not exceed one, and the number of administrations per week is between four and seven.

The fourth aspect of the present invention solves the above problems by providing a method for preventing emaciation disease in fish belonging to the Tetraodontiformes/Tetraodontidae family by preventing parasitism of one or both of Enteromyxum leei and Sphaerospora fugu in the body of fish belonging to the Tetraodontiformes/Tetraodontidae family, which comprises orally administering to said fish belonging to the Tetraodontiformes/Tetraodontidae family an oral composition containing salinomycin or a medicamentously acceptable salt thereof alone as an active ingredient such that the daily dose of the active ingredient is 0.5 to 5 mg per kg of fish body weight.

In the method for preventing emaciation disease in pufferfish according to the fourth aspect of the present invention, the amount of the active ingredient administered per dose is preferably 1 to 5 mg per kg of fish body weight.

In the method for preventing emaciation disease in pufferfish according to the fourth aspect of the present invention, the administration interval of the oral composition is preferably 12 hours or more and 72 days or less.

In the method for preventing emaciation disease in pufferfish according to the fourth aspect of the present invention, it is preferable that the number of administrations per day does not exceed one, and that the number of administrations per week is between four and seven.

According to the invention, there is provided an oral anthelmintic composition for pufferfish that enables the anthelmintic treatment and prevention of parasitism by Enteromyxum leei and Sphaerospora fugu in fish belonging to the Tetraodontidae family, an oral composition for preventing emaciation in pufferfish that enables the anthelmintic treatment and prevention of parasitism by the causative pathogen, and a method for anthelmintic treatment of myxosporean parasites in pufferfish and a method for preventing emaciation in pufferfish using these compositions.

<Anthelmintic oral composition for pufferfish and anthelmintic method using same>
One embodiment of the present invention relates to an oral anthelmintic composition for puffer fishes (hereinafter, sometimes abbreviated as "anthelmintic oral composition") for eliminating one or both of Enteromyxum leei and Sphaerospora fugu that are parasitic in the body of fishes belonging to the Tetraodontiformes and Tetraodontidae family, and another embodiment related to the embodiment relates to a method for eliminating (deworming) one or both of Enteromyxum leei and Sphaerospora fugu that are parasitic in the body of fishes belonging to the Tetraodontiformes and Tetraodontidae family (hereinafter, sometimes abbreviated as "anthelmintic method"). Since the active ingredient, dosage and administration interval in the oral anthelmintic composition and the anthelmintic method are common to both, hereinafter, the oral anthelmintic composition and the anthelmintic method will be described together without any particular distinction.

The anthelmintic oral composition is an oral composition that contains only salinomycin, a medicamentously acceptable salt thereof, or a mixture thereof as an active ingredient, and is used to eliminate one or both of Enteromyxum leei and Sphaerospora fugu that are parasitic in the body of fish belonging to the Tetraodontiformes and Tetraodontidae families. Note that "oral composition" refers to a composition for oral administration, and "containing only salinomycin, a medicamentously acceptable salt thereof, or a mixture thereof as an active ingredient" means that it contains only salinomycin, a medicamentously acceptable salt thereof, or a mixture thereof as an active ingredient for eliminating one or both of Enteromyxum leei and Sphaerospora fugu that are parasitic in the body of fish belonging to the Tetraodontiformes and Tetraodontidae families, and does not exclude the use in combination or simultaneous administration with a pharmaceutical composition having other efficacy or with other active ingredients.

Salinomycin is known as an ionophore therapeutic agent having antibacterial and coccidiostatic properties, and has the IUPAC name (2R)-2-[(5S,6R)-6-[(1S,2S,3S,5R)-5-[(2S,5R,7S,9S,10S,12R,15R)-2-[(2R,5R,6S)-5-ethyl-5-hydroxy-6-methyl-2-tetrahydropyranyl]-15-hydroxy-2,10,12-trimethyl-1,6,8-trioxadispiro[ ^{4.1.57.35 ]} pentadec-13-en-9-yl]-2-hydroxy-1,3-dimethyl-4-oxoheptyl]-5-methyl-2-tetrahydropyranyl]butanoic acid and CAS number 53003-10-4.

Salinomycin has a carboxyl group, and all or part of the carboxyl group may form a medicamentously acceptable salt. The counter ion (cation) that forms a medicamentously acceptable salt with the carboxyl group of salinomycin may be any ion as long as it does not have harmful effects such as toxicity on at least the administered amount of fish belonging to the Tetraodontidae family and the Tetraodon genus, does not exhibit properties unsuitable for medicinal use such as water insolubility, and has the desired pharmacological action. Specific examples include alkali metal ions such as sodium ions and potassium ions, alkaline earth metal salts such as magnesium salts and calcium salts, and ammonium salts.

As mentioned above, regarding the use of drugs to eradicate myxosporean parasites, the use of a combination of salinomycin sodium and amprolium (70 mg and 100 mg per kg of fish body weight, respectively) as an anthelmintic for the myxosporean Enteromyxum leei in European gilthead seabream and several fish species kept in aquariums has been reported, but there have been no reported cases of salinomycin being administered alone in small amounts, nor has it been administered to fish belonging to the Tetraodontiformes/Tetraodontiidae family.

The fish to which the anthelmintic oral composition is administered are any fish belonging to the family Tetraodontiformes (hereinafter sometimes abbreviated as "Tetraodontidae fish"). Preferably, the fish belonging to the family Tetraodontiformes (Tetraodontiformes) to which the anthelmintic oral composition is administered are farmed fish that develop emaciation disease due to infection with Enteromyxum leei or Sphaerospora fugu. Specific examples include fish belonging to the Lagocephalus genus (such as the white mackerel puffer, black mackerel puffer, and Japanese puffer), fish belonging to the Takifugu genus (such as the tiger puffer, crow puffer, red-eyed puffer, Sansai puffer, Kusafugu, Messing puffer, red-eyed puffer, common puffer, spotted puffer, Japanese puffer, and spotted puffer), and fish belonging to the Spheoeroides genus (such as the Japanese puffer).

The myxosporean parasites targeted for eradication by the oral anthelmintic composition are Enteromyxum leei and Sphaerospora fugu, which are causative pathogens of emaciation disease in pufferfish.

The anthelmintic oral composition is produced by mixing the above-mentioned active ingredient (salinomycin, a medicamentously acceptable salt thereof, or a mixture thereof) with any carrier used for oral administration. The active ingredient may be mixed with the carrier as a solid, or in the form of a solution such as an aqueous solution of a predetermined concentration. Any carrier may be used as the carrier as long as it is orally ingestible by pufferfish and does not have any harmful properties such as toxicity, but the most preferred carrier is fish feed. There are no particular restrictions on the form of the feed as long as it is one that is normally used in the culture of pufferfish. Specific examples include compound feeds in which fish meal or a portion of the fish meal is replaced with a vegetable protein-containing material such as dehulled soybean meal, corn gluten meal, rapeseed oil cake, cottonseed meal, sunflower meal, etc. as a protein source, and other nutritional sources such as potato starch, feed oil, inorganic compounds, vitamin mixtures, pregelatinized potato starch (for example, about 2 to 4% by weight), dextrin, etc. are mixed. There are no particular limitations on the form of the feed, so long as it is one that can be used in the aquaculture of pufferfish. For example, pellets, crumbles, and other forms that are easy for fish belonging to the pufferfish family to ingest are preferably used.

The daily dose of the above-mentioned active ingredient contained in the anthelmintic oral composition is 0.5 to 10 mg, preferably 1 to 10 mg, per kg of fish body weight. If the daily dose of the active ingredient is less than 0.5 mg per kg of fish body weight, a sufficient anthelmintic effect cannot be achieved, and if the daily dose of the active ingredient is more than 10 mg per kg of fish body weight, there is a risk of a decrease in the feeding rate. When using fish feed as a carrier for the anthelmintic oral composition, for example, the amount of feed consumed per day by one pufferfish fish (hereinafter referred to as "intake per fish per day") is calculated from the daily feed consumption, or an estimate of the intake per fish per day is obtained based on the average body weight of farmed pufferfish fish, and the above-mentioned dose of the active ingredient is added to the feed intake per fish per day. The average weight of pufferfish may be calculated by averaging the measured weights of all or part of the farmed pufferfish, or it may be estimated based on the number of days farmed or the age of the fish.

The administration interval of the anthelmintic oral composition is 12 hours or more and 72 days or less. If the administration interval is less than 12 hours, the anthelmintic effect saturates and the cost-effectiveness decreases, and if the administration interval is more than 72 days, sufficient anthelmintic effect cannot be obtained. When using feed as a carrier for the anthelmintic oral composition, it is preferable to match the administration interval with the feeding interval within the above-mentioned range. Specifically, the anthelmintic oral composition is orally administered to pufferfish fishes not more than once per day and not less than 4 times and not more than 7 times per week. As a specific example, the feed (anthelmintic oral composition) to which the above-mentioned active ingredient has been added is orally administered 4 to 7 times a week (5 times a week, for example, Monday to Friday excluding holidays) at a fixed feeding time once a day.

<Oral composition for preventing emaciation disease in pufferfish and method for preventing emaciation disease using the same>
Another embodiment of the present invention relates to an emaciation disease prevention agent composition for puffer fish (hereinafter, sometimes abbreviated as "emaciation disease prevention agent oral composition") that contains only salinomycin, a medicamentously acceptable salt thereof, or a mixture thereof as an active ingredient and is used to prevent the parasitism of one or both of Enteromyxum leei and Sphaerospora fugu in the body of fish belonging to the order Tetraodontiformes and the family Tetraodontiidae. Another embodiment related to the above embodiment relates to a method for preventing the parasitism of one or both of Enteromyxum leei and Sphaerospora fugu in the body of fish belonging to the order Tetraodontiformes and the family Tetraodontiidae (hereinafter, sometimes abbreviated as "emaciation disease prevention method"). Since the active ingredient, dosage, and administration interval in the emaciation disease prevention agent oral composition and the emaciation disease prevention method are common to both, hereinafter, the emaciation disease prevention agent oral composition and the emaciation disease prevention method will be described together without any particular distinction.

The active ingredient of the oral composition for preventing emaciation disease, the fish species to which it is administered, the myxosporean parasite to be prevented from infection, and the form of the oral composition are the same as those of the oral composition for preventing emaciation disease, and therefore detailed explanations are omitted. In addition, the dosage and administration interval of the oral composition for preventing emaciation disease are the same as those of the oral composition for preventing emaciation disease, except that the upper limit of the daily dosage of the active ingredient is 5 mg per kg of fish body weight, and therefore detailed explanations are omitted.

Example 1: Anthelmintic test using sodium salinomycin One-year-old tiger pufferfish that had developed emaciation disease were divided into two groups (administration group and control group) of about 5,000 fish each. The control group was fed a feed that did not contain sodium salinomycin, and the administration group was fed a feed (anthelmintic oral composition) containing sodium salinomycin (a mixed powder of rice bran oil cake, calcium carbonate, and liquid paraffin. The content of sodium salinomycin: 10% by weight) at a rate of 3 to 5 mg/BW (3 to 5 mg per kg of fish body weight) per weight equivalent to the daily food intake (administration by mouth) 5 times/week (Monday to Friday, once a day at a fixed time). Three and 12 weeks after the start of the test, 10 fish each were sampled from the administration group and the control group, and the average fish weight of each group and the average parasitism score (see Table 1 below) determined by visual inspection of the collected intestinal fluid under a microscope were determined, and the results of both groups were compared. The results are shown in Table 2 below. In Table 2, "*" indicates p<0.01, "**" indicates p<0.001, and "***" indicates p<0.0001.

The above results show that three weeks after the start of the study, the parasitism score in the treatment group was significantly improved compared to the control group. Even 12 weeks after the start of the study, the significant improvement in parasitism score in the treatment group was maintained, and the average fish weight in the treatment group was also significantly increased compared to the control group. These results confirm that administration of a low dose (3-5 mg/BW per day) of salinomycin sodium alone reduced parasitism score in the treatment group after three weeks due to the anthelmintic effect of myxosporean parasites, which are the causative agent of emaciation disease, and improved the condition of the intestinal mucosa, thereby improving nutritional status, resulting in a significant increase in fish weight compared to the control group.

Example 2: Test for preventing emaciation disease with salinomycin sodium Healthy tiger pufferfish of the year were divided into two groups (treatment group and control group) of about 5,000 fish each. The control group was fed a feed that did not contain salinomycin sodium, and the treatment group was fed a feed (emaceration disease preventive agent oral composition) containing salinomycin sodium (a mixed powder of rice bran oil cake, calcium carbonate, and liquid paraffin. The content of salinomycin sodium: 10% by weight) at a rate of 3 mg/BW (3-5 mg per kg of fish body weight) per weight equivalent to the daily food intake (oral administration) 5 times/week (Monday to Friday, once a day at a fixed time). One month, two months, three months, four months, five months, and six months after the start of the test, 10 fish each were sampled from the treatment group and the control group, and the average fish body weight of the treatment group and the average parasitism score (see Table 1 above) determined by visual inspection under a microscope of the collected intestinal fluid were determined. The results are shown in Table 3 below.

The above results confirmed that administration of a low dose of salinomycin sodium (3 mg/BW per day) maintained fish weight gain and low infestation scores (0-0.2) for six months, comparable to those of healthy tiger pufferfish that had not developed emaciation disease. The average infestation score in the control group was 2.8 six months after the start of the study. These results confirmed that the incidence of emaciation disease (increase in infestation score) was significantly suppressed in the treatment group compared to the control group.

Claims (14)

An oral anthelmintic composition for pufferfish, comprising as an active ingredient only salinomycin, a medicamentously acceptable salt thereof, or a mixture thereof, and being orally administered to fish belonging to the Tetraodontiformes, Tetraodontidae family in order to eradicate one or both of Enteromyxum leei and Sphaerospora fugu that are parasitic within the bodies of said fish. 2. The oral anthelmintic composition for pufferfish according to claim 1, wherein the daily dose of the active ingredient is 0.5 to 10 mg per kg of fish body weight. 3. The oral anthelmintic composition for pufferfish according to claim 2 , characterized in that the administration interval is from 12 hours to 72 days. 4. The oral anthelmintic composition for pufferfish according to claim 3 , characterized in that the number of times per day is not more than once and the number of times per week is between 4 and 7. An oral composition for preventing emaciation disease in pufferfish, comprising only salinomycin, a medicamentously acceptable salt thereof, or a mixture thereof as an active ingredient, and being orally administered to fish belonging to the Tetraodontiformes, Tetraodontiidae family to prevent infestation of one or both of Enteromyxum leei and Sphaerospora fugu in the bodies of said fish. 6. The oral composition for preventing emaciation disease in pufferfish , characterized in that the daily dose of the active ingredient is 0.5 to 5 mg per kg of fish body weight. 7. The oral composition for preventing emaciation disease in pufferfish according to claim 6 , characterized in that the administration interval is from 12 hours to 72 days. 8. An oral composition for preventing emaciation disease in pufferfish according to claim 7 , characterized in that the number of times administered per day is not more than once and the number of times administered per week is between 4 and 7. A method for eliminating one or both of Enteromyxum leei and Sphaerospora fugu that are parasitic in fish belonging to the Tetraodontiformes, Tetraodontiidae family, comprising:
A method for exterminating myxosporean parasites in Tetraodontiformes, comprising the step of orally administering to said fish belonging to the Tetraodontiformes/Tetraodontiidae family an oral composition containing salinomycin or a medicamentously acceptable salt thereof alone as an active ingredient such that the daily dosage of said active ingredient is 0.5 to 10 mg per kg of fish body weight. 10. The method for exterminating myxosporean parasites in pufferfish according to claim 9 , characterized in that the administration interval of the oral composition is from 12 hours to 72 days. 11. The method for anthelmintic myxosporean parasites for pufferfish according to claim 10 , characterized in that the number of administrations per day does not exceed one, and the number of administrations per week is between four and seven. A method for preventing parasitism of one or both of Enteromyxum leei and Sphaerospora fugu in fish belonging to the Tetraodontiformes, Tetraodontiidae family, comprising:
A method for preventing emaciation disease in pectinidae fish, comprising a step of orally administering to said fish belonging to the Tetraodontiformes/Tetraodontiidae family an oral composition containing salinomycin or a medicamentously acceptable salt thereof alone as an active ingredient such that the daily dosage of said active ingredient is 0.5 to 5 mg per kg of fish body weight. 13. The method for preventing emaciation disease in pufferfish according to claim 12 , characterized in that the administration interval of the oral composition is from 12 hours to 72 days. 14. A method for preventing emaciation disease in pufferfish as described in claim 13 , characterized in that the number of administrations per day does not exceed one, and the number of administrations per week is between four and seven.