JPH0134581B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to the cultivation of bright-colored fish, and more particularly to a method for cultivating cultured bright-colored fish having the same body color as that of natural bright-colored fish. In recent years, the shortage of fish has been brought into focus due to global population growth, but natural fish have their limits, and one way to solve the fish shortage is to artificially mass-produce useful fish. Fish farming has been put into practical use in some areas. In addition, the cultivation of ornamental fish has already been put into practical use, and the cultivation of fish for the purpose of meat, feed, or ornamental use has already been put into practical use, and examples of saltwater fish include red sea bream, red sea bream, yellow sea bream, and black sea bream. These include the bream family, such as the bream fish, the horse mackerel family, such as the amberjack, the cylindrical family, such as the amberjack, and the carp, and the freshwater fish such as the kingfish and the common carp. However, these artificially cultured fish have drawbacks such as their body color being less vivid than that of natural fish. For example, in the case of red sea bream, compared to wild red sea bream, farmed red sea bream cannot produce a fish with a bright red body color similar to that of wild red sea bream, and only black sea bream-like red sea bream with a black body color can be obtained, making it less marketable. The decline in fish production has become a problem and a major concern for those involved in aquaculture. In addition, various researches have been carried out by various public and private research institutes over the past ten years to prevent the blackening of red sea bream, etc. However, effective aquaculture methods have not been obtained, and some methods are currently being used. Although red pigments have been added to fish feed and black pigments have been restricted, sufficient body color expression and black color prevention effects have not yet been achieved in wild red sea bream. In order to improve this drawback, the present inventors conducted research mainly in relation to light quality conditions, and found that bright colors can be obtained under a light quality atmosphere in which there is substantially no light in the wavelength range of at least 360 nm or less. It has been found, quite unexpectedly, that when fish are farmed, cultured bright-colored fish can be obtained that have the same body color as that of natural bright-colored fish. According to the invention, therefore, at least 360 nm
Provided is a method for cultivating bright-colored fish, which comprises cultivating bright-colored fish in a light quality atmosphere in which light in wavelength ranges of 1 and 2 and below is substantially absent. The brightly colored fish to which the method of the present invention is applied refers to fish with a colored body color, but generally refers to fish with a bright color tone, and the body color of the fish is red, yellow, blue, etc. Fish with bright green hues are particularly susceptible to the effects of the present invention. Particularly preferred are red fish. Preferably applied fish include, for example, the following species belonging to the phylum Vertebrata, the teleost fishes, and the teleost subfamily. 1 Perciformes, suborder Perciformes, Red sea bream, Red sea bream, Yellow sea bream, Yellowfin sea bream, Chichinu, Red sea bream, etc. Grouper family Sakura sea bream, Red sea bream, Red sea bream,
Southern redfish, Shikishimahana seabream, Red scorpion, etc. Suborders of the Oriental fish Family: The family of the Oriental fishes: Amberjack, Yellowtail, Thrushfish, Redfish, etc. Amberfish, Amberfish, etc.
Horse mackerel, Japanese horse mackerel, etc. 2 Carp order Cyprini suborder Cyprinidae ● Carp (Nishiki carp → Kouhaku, Sankei, Taishiyousanke, Shiyouwasanke, Betsukou, etc.) ● Crucian carp (Kingiyo → Ryuukin, Wakin, Oranda shigashira, Hanafusa, etc.) Preferably, the Carp family, Groupers, Cyprinidae, etc.
More preferred are red sea bream, red sea bream, carp, crucian carp, etc., and most preferred are red sea bream, etc. The cultivation of the above-mentioned bright-colored fish by the method of the present invention is carried out at least 360 nm and below, more preferably
The process is carried out in a light atmosphere in which there is substantially no light in the wavelength range of 380 nm or less. In this specification, the term "optical atmosphere in which light in the wavelength range of X nm and below is substantially absent" preferably means a light quality atmosphere in which light in the wavelength range of X nm and below is completely absent. However, it means that there is no problem even if light in this wavelength range is present in a small amount that does not adversely affect the aquaculture of the present invention. Therefore, in aquaculture under sunlight irradiation,
The transmission of light in the wavelength range in sunlight is at least 60
%, preferably 70%, particularly preferably 80%, even more preferably 90%, most preferably 95% to 100%.
On the other hand, when using artificial light, use an optical filter as necessary to reduce the amount of light in the wavelength range.
1000 μw/cm ² or less, preferably 500 μw/cm ² or less,
It is desirable to culture under artificial light irradiation, more preferably from 500 to 100 μw/cm ² , most preferably from 50 to 0 μw/cm ² . In addition, under light quality conditions under sunlight irradiation, light wavelength (horizontal axis X, unit nm) versus light transmittance (vertical axis f
(x), unit %) When a curve is drawn, the light wavelength
is 340nm≦X≦420nm, and the light transmittance f(x) is 2≦
It is particularly preferable that as X increases in the region of f(x)≦100, f(x) also increases. In other words, the light transmittance corresponding to the light wavelength X _o is f(X _o ), the transmittance corresponding to the wavelength range X ₂ is f(X ₂ ), and the transmittance corresponding to the wavelength X ₃ which is longer than the wavelength X ₂ is Transmittance f(X ₃ ), transmittance f(X ₄ ) corresponding to wavelength X ₄ which is longer than wavelength X ₃ ..., 340nm≦
X, _≦ 430nm In _{the region of} f(x)≧Z _, according to X _{2 <} It is particularly preferable that the following relationship exists: f(X _o )...≦100. In addition to the above, when the wavelength at which the light transmittance is 2% is expressed as X _a , the light transmittance at a wavelength 40 nm longer than X _a (X _a +40) (f(X _a +40))
It is particularly desirable that f(X _a +40)≧10, more preferably f(X _a +40)≧20. On the other hand, in order to cultivate brightly colored fish, it is necessary to irradiate a certain amount of light in the visible light range, and generally there is light in the wavelength range of at least 550 nm and above, more preferably at least 450 nm and above. It is desirable to carry out aquaculture in an atmosphere with good light quality, but in some cases it is also possible to carry out aquaculture in an atmosphere with good light quality that blocks 70% or more of the visible light range, or even 90% or more, or even 95% or more of the visible light range. You can also. These vary greatly depending on the type of brightly colored fish to be cultured, water depth, etc., and cannot be generalized, but the appropriate amount and intensity of light in the wavelength range of 550 nm and above can be determined by conducting small-scale experiments. , can be easily determined by a person skilled in the art. Therefore, the cultivation of bright-colored fish according to the present invention does not require any special cultivation conditions other than the restriction of using the above-mentioned specific light quality atmosphere, and is not necessary for the cultivation of bright-colored fish, which has been conventionally carried out for bright-colored fish such as red sea bream. This can be done according to the cultivation method and conditions. As a method of forming the above-mentioned specific light quality atmosphere, for example, at least
Artificial light that does not contain light in the wavelength range of 360 nm and below, more preferably 380 nm and below, and preferably contains light in the wavelength range of 550 nm and above [In this case, the artificial light source itself does not contain light in the wavelength range of 550 nm and above. A method of irradiating an artificial light source (which may emit characteristic light, or by covering an artificial light source with a suitable filter so that the emitted light has the light quality characteristics described above); Under irradiation with light, at least 360 nm and below, as described below,
More preferably, a method of coating with a coating material that substantially blocks the transmission of light in a wavelength range of 380 nm or less, and a combination of both of the above methods can be considered. For example, the case of culturing red sea bream, which is a brightly colored fish, according to the present invention will be described as an example. In general, red sea bream farming uses wild red sea bream caught in nearby waters (also called natural seedlings), depending on the age of the fish (approximately 6 to 9 g/fish of red sea bream that has been hatched for about 5 months). , 1-year-old fish (approximately 40 to 100 g/fish of red sea bream that has passed about 1 year since hatching), 2-year-old fish (approximately 100 red sea bream that has passed about 2 years since hatching)
~250g/fish), 3-year-old fish and 4-year-old fish (3-year-old fish after hatching)
Separate the fish from older red sea bream (approximately 250 g or more) by size, place them in cages of a size appropriate for each fish depending on its age, and cultivate it for 1 or 2 years before shipping it to the market. . As a suitable place for aquaculture, seawater flows at a rate of 5 to 15 cm/sec, always has dissolved oxygen of 5 c.c./sec, has a water temperature of 20 to 28 degrees Celsius, has low salinity, has no inflow of waste water, and is free from red tide. Select a sea area where there is no environmental deterioration such as outbreaks, make a square out of galvanized copper pipes with a diameter of about 5 cm and measuring 4 to 20 m on each side, and place 2 to 2 floats on each side.
Attach four nets, float on the sea, and set a net there at a depth of about 5 to 7 meters. Wild red sea bream are usually caught from August to September every year and are cultured in the above-mentioned culture net. The breeding density of red sea bream varies depending on the size of the red sea bream caught at this time, but generally ``0-year-old fish'' weighing less than 10g are 100 fish/fish.
^m3 , 50-70 fish/1-2 year old fish (150g/tail)
m ³ (7 to 11 Kg/m ³ ) is appropriate. Live bait is used for aquaculture, and mixed feed and fish feed oil are used.The raw bait is mainly fresh or frozen fish such as anchovies, mackerel, horse mackerel, and sand eel, which is then made into minced meat and fed. do. Compound feeds contain nutrients such as protein, fat, carbohydrates, vitamins, and minerals, and are commercially available in various types. Fish oil is mainly used for fish feed oil. The amount of bait to be fed varies greatly depending on the size of the fish, water temperature, etc., but when feeding fish meat to 0-year-old fish (6 to 9 g/fish), generally about 20 kg/1000 fish x 10 days, 1~
Approximately 3500Kg/1000 fish x 30 for 2 year old fish (100g/fish)
It is day. Wild red sea bream has a beautiful bright red body color, but when farmed, the black color becomes noticeable within two weeks of cultivation, and after 40 days it becomes blackish. For this reason, some feeders use feed containing red pigments, especially carotenoids, or feed with krill, red shrimp, northern shrimp, etc. that contain large amounts of carotenoids, but the body color is bright red like that of wild red sea bream. It does not change color but becomes dark brown or reddish brown,
Marketability is low. When the method of the present invention is actually applied to the cultivation of the red sea bream described above, the coating material of the present invention, which will be described later, is applied to a small sea-surface type aquaculture facility installed in a cove or bay where the waves are relatively calm. Expanding and cultivating red sea bream. The material of the present invention may be installed in the sea or on the sea surface, or both may be used in combination, and it is preferable to install the material between the cultured fish and the sun or an artificial light source. A preferred method of carrying out the method of the present invention is to carry out the cultivation of brightly colored fish as described above using a coating material capable of forming said specific light quality atmosphere, i.e. at least 360 nm and below, particularly preferably at least 380 nm. and preferably at least 550 nm and above, more preferably 450 nm
This is done under the covering of a transparent covering material that substantially transmits light in the wavelength range of m and above. Here, "substantially blocking" the transmission of light in the above wavelength range means not only completely blocking the transmission of light in the wavelength range by 100%, but also blocking transmission of light in the wavelength range by up to 40%. This means that 550nm is allowed.
"Substantially transmitting" light in the wavelength range above and beyond means that it completely transmits 100% of the light in the wavelength range, but it also means that the transmission of light in the wavelength range is slightly blocked and the transmission of the light This means that there is no problem even if the ratio decreases to 5%, preferably 10%, and more preferably 70%. In the above coating material, light in the wavelength range from 360 nm to 550 nm may be substantially transmitted or substantially blocked, but generally the average transmittance of light in the wavelength range is 10. It is suitable to keep it within the range of ~95%, preferably 30~90%. According to the present invention, there is provided a coating material for cultivating bright-colored fish having the above-mentioned light transmission characteristics. As the coating material of the present invention, there are no particular restrictions on the material, etc., and any type of coating material can be used as long as it has the above-mentioned light transmission characteristics. Such a covering can usually consist of an inorganic or organic film, plate, or other molded body. For example, inorganic films or plates typically include glass plates mixed with dyes or pigments (e.g. emerald green), glass plates coated with or laminated with synthetic resin films containing ultraviolet absorbers as shown below, etc. As the organic film or plate, a synthetic resin film or plate coated with or containing an ultraviolet absorber is particularly suitable. In addition, as a covering material for floating on the water surface, a synthetic resin impregnated with an ultraviolet absorber as described below is molded into a box-like, hollow-like, or foam-like shape so as to float on the water surface. can also be used. In addition to the thermoplastic resins described below, thermosetting resins such as melamine resins, phenolic resins, epoxy resins, silicone resins, urea resins, alkyd resins, and allyl phthalate resins can also be used as resins that can be used for this molding. be able to. However, in the present invention, a synthetic resin film or plate containing an ultraviolet absorber is particularly suitable as the covering material, and this synthetic resin film or plate will be explained in more detail below. The transparent film or plate that can be used in the present invention can be produced, for example, by blending a suitable ultraviolet absorber with a normal film-forming thermoplastic resin and molding the mixture into a film or plate. Examples of usable film-forming thermoplastic synthetic resins include polyvinyl chloride, polyvinylidene chloride, polyethylene, polypropylene, polystyrene, polyester, polyamide, polycarbonate, polymethyl methacrylate, polyacrylate, polyvinyl acetate, polyvinyl alcohol,
Fluorine-containing resin, cellulose resin, ABS resin, etc.
It also includes copolymers or blends containing these polymers as the main component (preferably 50% by weight or more), particularly polyvinyl chloride, polyethylene, polypropylene,
Polyester, fluorine-containing resin, cellulose resin, and polystyrene are preferred. In addition, an ultraviolet absorber that can be blended into a synthetic resin such as the one described above and has the ability to substantially block the transmission of light with a wavelength of at least 360 nm or less should be compatible with the ultraviolet absorbing ability of the ultraviolet absorber and the synthetic resin used. They can be appropriately selected and used from a wide range of types in consideration of compatibility and the like. Examples of usable ultraviolet absorbers include the following. Hydroquinone series: Hydroquinone, hydroquinone disalicylate Salicylic acid series: Phenyl salicylate, paraoctylphenyl salicylate Benzophenone series: 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-
Octoxybenzophenone, 2-hydroxy-
4-methoxy-2-carboxybenzophenone, 2,4-dihydroxybenzophenone,
2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2-hydroxy-4-benzoyloxybenzophenone, 2,2'-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy -5-Sulfonebenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 2,2'-hydroxy-4,4'-dimethoxy-5-sodium sulfonebenzophenone, 4-dodecyloxy -2-hydroxybenzophenone, 2-hydroxy-5-chlorobenzophenone benzotriazole series: 2-(2'-hydroxy-
5′-methylphenyl)benzotriazole, 2
-(2'-hydroxy-5'-methylphenyl)-5
-butoxycarbonylbenzotriazole, 2
-(2'-hydroxy-5'-methylphenyl)-
5,6-dichlorobenzotriazole, 2-
2'-hydroxy-5'-methylphenyl)-5-
Ethylsulfonebenzotriazole, 2-
(2'-hydroxy-5'-tert-butylphenyl)
-5-chlorobenzotriazole, 2-(2'-
Hydroxy-5'-tert-butylphenyl)benzotriazole, 2-(2'-hydroxy-5'-
aminophenyl)benzotriazole, 2-
(2′-hydroxy-3′,5′-dimethylphenyl)
Benzotriazole, 2-(2'-hydroxy-
3′,5′-dimethylphenyl)-5-methoxybenzotriazole, 2-(2′-methyl-4′-hydroxyphenyl)benzotriazole, 2-
(2'-stearyloxy-3',5'-dimethylphenyl)-5-methylbenzotriazole, 2-
(2′-hydroxy-5′-ethoxycarbonylphenyl)benzotriazole ethyl ester,
2-(2'-hydroxy-3'-methyl-5'-tert-
butylphenyl)benzotriazole, 2-
(2'-hydroxy-3',5'-di-tert-butylphenyl)-5-chloro-benzotriazole,
2-(2'-hydroxy-5'-methoxyphenyl)
Benzotriazole, 2-(2'-hydroxy-
5'-Phenylphenyl)-5-chlorobenzotriazole, 2-(2'-Hydroxy-5'-cyclohexylphenyl)benzotriazole, 2
-(2'-hydroxy-4',5'-dimethylphenyl)-5-butoxycarbonyl-benzotriazole, 2-(2'-hydroxy-3',5'-dichlorophenyl)benzotriazole, 2-(2' −
Hydroxy-4',5'dichloro)benzotriazole, 2-(2'-hydroxy-3',5'-dimethylphenyl)-5-ethylsulfonebenzotriazole, 2-(2'-hydroxy-5'-phenylphenyl) ) benzotriazole, 2-(2'-hydroxy-4'-octoxyphenyl)benzotriazole, 2-(2'-hydroxy-5'-methoxyphenyl)-5-methylbenzotriazole, 2-(2'-hydroxy-5'-methylphenyl)-5-ethoxycarbonylbenzotriazole,2-(2'-acetoxy-5'-methylphenyl)benzotriazole,2-(2'-hydroxy-3',5'-ditashary) butyl phenyl)
-5-chlorobenzotriazole, 2-(2'-
Hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2
-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)5,6-dichlorobenzotriazole, 2-(2'-hydroxy-3',5'-di-
tert-butylphenyl)-4,5-dichlorobenzotriazole. Among these ultraviolet absorbers, benzophenone-based and benzotriazole-based ones are preferred; among the benzophenone-based ones, 2,3'-dihydroxy-4,4'-dimethoxybenzophenone,
2,2'-dihydroxy-4-methoxybenzophenone and 2,2',4,4'-tetrahydroxybenzophenone; in benzotriazole series, 2-
(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-5'-methylphenyl)-5,6-dichlorobenzotriazole, 2-(2'-hydroxy-5'-tert- butylphenyl) benzotriazole, 2-(2'-hydroxy-3'-methyl-5'-tert-butylphenyl)
Benzotriazole, 2-(2'-hydroxy-3',
5'-di-tert-butylphenyl)-5-chloro-benzotriazole and 2-(2'-hydroxy-
5'-Phenylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3',5'-dita-
Shaybutylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-5'-octoxyphenyl)benzotriazole, 2-(2'-hydroxy-3'-tert-butyl-5'- methylphenyl)-5-chlorobenzotriazole, 2-(2'-
Hydroxy-3'-tert-butyl-5'-methylphenyl)-5,6-dichlorobenzotriazole and the like are effective. Particularly suitable UV absorbers have the formula

[Formula] or In the formula, R ₁ and R ₂ are the same or different and each represents a lower alkyl group or an aryl group (especially a phenyl group), and in particular R ₁ is preferably a branched lower alkyl group or a phenyl group having C ₅ or less. is a benzotriazole derivative represented by R ₃ represents a C ₆ or higher alkyl group, especially a C ₈ to _{C 10} alkyl group, and X is a hydrogen atom or a halogen atom, especially a chlorine atom. The amount of the ultraviolet absorber as described above can be varied widely depending on the type of ultraviolet absorber, the type of synthetic resin used, the thickness of the film or plate, etc. In order to substantially block the transmission of ultraviolet rays of 380 nm and below, particularly preferably 380 nm and below, the following formula 15≦AB≦600 should be established between the amount of the ultraviolet absorber and the thickness of the resulting film or plate. Preferably, 20≦AB≦400, where A represents the blending amount (PHR) of the ultraviolet absorber, and B is the thickness (μ) of the film or plate.
It has been found that it is particularly preferable that the relationship expressed by is satisfied. Here PHR means synthetic resin
Means parts by weight per 100 parts by weight. In addition, the amount (A) of the UV absorber varies depending on the type of synthetic resin and UV absorber, but in general
0.001~5PHR, especially for film 0.1~5.00HR
A range of is suitable. In addition to the ultraviolet absorber, the synthetic resin used in the present invention may contain other usual resin additives, if necessary.
For example, small amounts of plasticizers, lubricants, antioxidants, light stabilizers, antistatic agents, moisturizers, heat stabilizers, dyes, pigments, algae, shellfish, and other dust adhesion prevention agents may be included. . In addition, the synthetic resin film or plate used in the present invention, or the above-mentioned molded product, can be produced by various methods known per se, such as a calendar method,
Melt extrusion method such as inflation method, press method,
It can be manufactured using a solution casting method, an injection molding method, or the like. Further, in order to prevent deterioration of the physical properties of the film, it may be coated with another resin or laminated with another film. The film or plate thus formed is
The thickness can be varied over a wide range depending on the intended use, but generally a range of 15 to 5,000 microns, particularly 20 to 3,000 microns, is suitable for the purpose of the present invention. The film or plate can also be used by laminating it on other synthetic resin film sheets, glass, etc. for the purpose of reinforcement, etc., if necessary. Furthermore, the synthetic resin film or plate formed as described above, particularly the film, may be reinforced with reinforcing fibers such as glass fibers, wire mesh, or reticular fiber structures. In addition, in order to prevent the transparency of the coating material of the present invention from decreasing due to adhesion of shellfish, algae, and other dust, surface treatment with an agent that prevents the adhesion of shellfish and algae, or It may also be laminated or coated with other synthetic resins containing drugs. When forming the specific light quality atmosphere using the coating material according to the present invention, it is not necessary to completely seal the entire culture system for brightly colored fish from ultraviolet rays in the specific wavelength range. Generally, the coating may be applied to at least the algae of bright-colored fish so as to substantially prevent irradiation of light in the wavelength range that may be present in irradiation light (for example, direct sunlight). The method of coating with the coating material of the present invention may be applied to areas where brightly colored fish are cultivated (pools, ponds, lakes, coves, bays, etc.)
A method of assembling a frame on the water surface and spreading the coating material of the present invention on the frame; a method of spreading it in contact with the water surface (as if floating); a method of installing a support in the water and spreading it; or a combination of these. Different methods are adopted depending on the culture environment, growth stage, etc. For reference, FIG. 2 shows a typical example of a raw material coated with the coating material of the present invention. According to the present invention described above, the body color of cultured bright-colored fish is almost the same as natural bright-colored fish, and the body color retention of bright-colored fish after landing is also improved, as is clear from the examples described later. It has the advantage that there is no major difference in body color from natural bright-colored fish, and its appearance is exactly the same as natural bright-colored fish. Next, the present invention will be explained with reference to Examples. Example A (Preparation of coating materials of the present invention and comparative examples) (1) 100 parts by weight of polyvinyl chloride, 45 parts by weight of dioctyl phthalate (plasticizer), 1.0 parts by weight of dibutyltin maleate (thermal stabilizer), stearic acid ( lubricant) 0.1 part by weight, and 2-(2'-hydroxy-3',
1.5 parts by weight of 5'-dithyabutylphenyl)-5-chlorobenzotriazole was mixed, and the mixture was melt-extruded at 200°C using an extruder to obtain a 0.05 mm transparent film.
A 0.5 cm square mesh made of polyester fibers was bonded between the two films to obtain a mesh film. From now on, this film will be used as coating material No.F.
-1 and was used as a coating material in Examples described later, and its light transmission curve is shown in FIG. (2) In (1) above, 2- which is an ultraviolet absorber
A reticulated film was obtained in the same manner as in (1) above, except that the amount of (2'-hydroxy-5'-methylphenyl)-benzotriazole was changed to 1.4 parts by weight. The light transmission curve is shown in Figure 1. (3) In the above (1), except that the film thickness was changed to a 0.1 mm film, a film was obtained in the same manner as in (1) above, and it was bonded between two 3 mm glass plates to make a composite glass plate. Obtained. This was hereinafter referred to as coating material No. G-1, and its light transmission curve is shown in FIG. (4) 100 parts by weight of methyl methacrylate, 2-
(2'-Hydroxy-3',5'-dithyabutylphenyl)-5-chlorobenzotriazole
0.055 parts by weight was melt-extruded using an extruder to obtain a 3.0 mm transparent plate. This is hereinafter referred to as coating material No. F-3, and its light transmission curve is shown in FIG. (5) 100 parts by weight of polyvinyl chloride, 42 parts by weight of dioctyl phthalate (plasticizer), 4 parts by weight of tricresyl phosphate (plasticizer), 2 parts by weight of epoxidized soybean oil (plasticizer), barium stearate ( heat stabilizer) 0.3 parts by weight, zinc stearate (heat stabilizer) 0.4 parts by weight, titanium oxide 2 parts by weight,
1.5 parts by weight of 2-(2'-hydroxy-3',5'-dithyabutylphenyl)-5-chlorobenzotriazole (ultraviolet absorber), Kayalon Polyester Blue BL-SF (blue pigment, Japanese 0.13 parts by weight (manufactured by Yakuhin Co., Ltd.) was mixed and extruded using an extruder at 200°C to extrude it into a 0.1 m/
A transparent film of m was obtained. This film was hereinafter referred to as coating material No. F-4, and its light transmission curve is shown in FIG. (6) In (1) above, a reticulated film was obtained in the same manner as in (1) above except that the ultraviolet absorber was not added. The curve is shown in FIG. Examples 1 to 5 and Comparative Examples 1 to 3 Films of 0.1 m/m were obtained in the same manner as in (5) above, except that the ultraviolet absorber was not added. This film was hereinafter referred to as coating material No. F-6, and its light transmission curve is shown in FIG. Between July 20th and September 5th, 1,000 red sea bream (natural seedlings) with an average fish weight of 6.6 g/tail size at the start of aquaculture were harvested from seawater off the coast of Fukuoka Prefecture due to a slight flow of seawater off the coast of Fukuoka Prefecture. The fish cage shown in Figure 2 A (vertical x horizontal x depth, approximately 2 m x 2m x 2.5m) and cultured. Eight fish cages were prepared, and the coating material prepared in Example A was applied to the galvanized steel pipe frame above the sea surface of each fish cage, and red sea bream were cultured according to Table 2. The results of culturing are also listed in Table-2. Table 2 shows that by applying the method of the present invention, the body color of farmed red sea bream was significantly improved, the bright red color of wild red sea bream was obtained, and the body color retention after landing was also improved. There was no major difference between the red sea bream and the red sea bream, and in terms of appearance, it became indistinguishable from the wild red sea bream. Furthermore, the material of the present invention tended to suppress the mortality rate of wild red sea bream seedlings and slightly promote the growth of red sea bream. In addition, the word "meai" in Section 16 above refers to the mesh size, which is a term used to describe the size of the mesh. According to the meaning, for example, the 16th section is 20.2mm,
18 stitches corresponds to 17.8mm stitches. In addition, the fish meat that was fed was small anchovies,
The animals were fed with fresh or frozen mackerel and mackerel, which was made into minced meat.

[Table] The body color (at the time of landing) and the retention of body color 10 hours after landing were determined according to Table 3 below.

【table】

[Table] Examples 6-7, Comparative Examples 4-5 The results of culturing 1-year-old and 2-year-old wild red sea bream as seeds are shown in Tables 4 and 5. The feed used here was the same fish meat as in Example-1.

【table】

[Table] Examples 8 to 9, Comparative Examples 6 to 7 Methyl methacrylate water tank (length x width x height, 30 cm x 30 cm
Each aquarium was completely covered with the coating material shown in Table 4, and 3 fish of approximately 5 cm in size were stocked in each tank, and air was constantly pumped in at 500 ml/min. Each aquarium was heated to approximately 4,000 lux from September 1st to September 30th using a Toshiba sunlight lamp (manufactured by Toshiba Electric Materials Co., Ltd.) and a Black fluorescent lamp (FL20S-BLB, manufactured by Tokyo Shibaura Electric Co., Ltd.).
Ryukin was cultivated under irradiation of 6000 lux and its body color was tested. The water temperature in each tank was kept at 20-25°C.

[Table] Table 6 shows that in Comparative Examples 6 and 7, the degree of red color of the lily pads became slightly lighter compared to before the start of aquaculture, whereas in Examples 8 and 9, the degree of red color did not change from before the start of aquaculture. The material of the present invention retains its deep red color, indicating that it is highly effective in maintaining the body color of the lily. Comparative Example 8 Red sea bream was cultured in the same manner as in Example 5 except that No. F-6 was used as the coating material. The culture results are listed in Table-2. Compared to Example 5, the body color of the red sea bream was noticeably worse.

[Brief explanation of drawings]

FIG. 1 is a light transmittance curve according to wavelength of coating materials No. F-1 to F-5 and No. G-1 used in Examples 1 to 9 and Comparative Examples 1 to 7. FIG. 2 shows a typical fish cage covered with the coating material of the present invention, where a is the coating material of the present invention, b is a steel pipe, c is a tread, d is the sea surface,
e is the cage net and f is the anchor. FIG. 3 is a light transmittance curve for each wavelength of coating material No. F-6 used in Comparative Example 8.

Claims (1)

[Scope of Claims] 1. A method for cultivating bright-colored fish, which comprises cultivating bright-colored fish in a light atmosphere in which at least 40% of light in the wavelength range of 360 nm or less does not exist. 2. The method according to claim 1, characterized in that the brightly colored fish are cultured in a light quality atmosphere in which at least 40% of the light in the wavelength range of 380 nm and below does not exist. 3. The method according to any one of claims 1 to 2, wherein the brightly colored fish is a brightly colored fish having a reddish body color. 4. The method according to claim 3, wherein the brightly colored fish having a red body color is red sea bream.