JP3967229B2 - Ayu breeding method - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a method of raising sweetfish for the purpose of preventing the occurrence of fish diseases.
[0002]
[Prior art]
Ayu has long been an important target for edible and river fishing, and is cultivated for edible or river discharge almost all over the country.
[0003]
Ayu seedlings used for aquaculture were mainly ayu collected from Lake Biwa and marine ayu collected from the sea until a long time ago. Is increasing year by year. It is well known that these sweetfish have fish diseases that significantly reduce the survival rate in the aquaculture process or fatally reduce the commercial value in the aquaculture process, as in other aquaculture target fish. And Pseudomonas disease are causing major damage nationwide.
[0004]
As countermeasures against fish diseases, (1) avoid contact between susceptible hosts and pathogenic bacteria, (2) maintain an environment in which specific diseases are unlikely to occur, (3) give preventive immunity against specific pathogenic bacteria, (4) ▼ Treatment using an effective drug against the pathogenic bacteria (Muroga Kiyokuni, Shuzo Egusa, “Introduction to Fish Pathology”, Hoshiseisha Koseikaku, p. 47 (1996)), etc. According to the Fisheries Agency's “Use of pharmaceuticals for fisheries” 13th report (1999), oxalonic acid, sulfamonomethoxine or its sodium salt, sulfamonomethoxine and olmethoprim combination, florfenicol , Sulfisosol or its sodium salt is specified. As for preventive immunity, the use of a sweetfish inactivated vaccine for sweetfish has been approved for the prevention of vibrio disease.
[0005]
Drug baths with iodo drugs (made by Meiji Seika Co., Ltd., “Isodin for fisheries” (registered trademark) 10% by mass) for oocyte eggs for the purpose of sterilizing pathogenic bacteria are commonly practiced in moss. Usually, the treatment is carried out at an effective iodine concentration of 25 to 50 ppm for 15 minutes, but the treatment at 100 ppm for 30 minutes has no effect on the hatching rate (Satoshi Yamamoto, “Breeding management to prevent disease ( Freshwater fish), aquaculture ", Green Shobo, Vol. 31, No. 2, pp. 63-66 (1994)).
[0006]
[Problems to be solved by the invention]
For fish diseases, various conventional measures are known. However, it is very difficult to prevent the damage in reality, which greatly reduces the productivity of sweetfish and is a major management pressure factor. It has become. It is an object of the present invention to prevent the occurrence of fish disease by establishing a method for blocking the infection route of fish disease and eliminating pathogenic bacteria from the breeding environment.
[0007]
[Means for Solving the Problems]
In the case of cold water disease, for example, in the case of cold water disease, the present inventors have found that Flavobacterium which is a causative fungus in the ovarian cavity fluid and seminal plasma of parent fish used for egg collection and semen collection in artificial seedling production・ Cyclophyllum exists and is the source of infection, but in the case of sweetfish, the causal germ does not enter the fertilized egg, and the causal germ adheres to the walls and walls of the breeding tank. It has been confirmed that it is a source of infection. In consideration of these results, we have intensively studied fertilized eggs and breeding environment treatment methods aimed at blocking infection routes, and found that these problems can be solved by treating them under certain conditions. The invention has been completed.
[0008]
That is, the present invention relates to a method for cultivating an ayu egg sterilized completely sterilized with an iodine preparation or a larvae hatched from the egg laid in an aquarium completely sterilized with hypochlorite and a breeding environment. It is.
[0009]
Specifically, after spraying a hypochlorite solution having an effective chlorine concentration of 0.005 to 0.015% by mass on the walls and bottom of the washed and dried breeding tank, the breeding tank has an effective chlorine concentration of 0.005. Filled with ~ 0.015 mass% hypochlorite solution and circulated for 1-2 days, then neutralized with thiosulfate and then drained to ensure fish safety Therefore, once the breeding water that does not contain pathogenic bacteria causing fish disease is filled and drained, the breeding water is filled again. In the breeding aquarium, larvae and larvae hatched from eyed eggs immersed in povidone-iodine solution having an effective iodine concentration of 2.5 to 7.5 μg / ml for 20 minutes to 1 hour are housed. It is related with the breeding method of ayu which prevents the outbreak of a fish disease by these.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The eye egg according to the present invention refers to an egg at the time when eyes are recognized from the outside as two small sunspots in the embryo body about 10 days after insemination in artificial insemination of sweetfish. If the immersion treatment in povidone-iodine solution is performed before the eye development time, it will result in a significant decrease in the survival rate. The effective iodine concentration of the povidone-iodine solution can be appropriately selected within the range of 2.5 to 7.5 μg / ml. At a concentration of 2.5 μg / ml or less, a sufficient bactericidal effect cannot be obtained. Conversely, when it is set at a concentration higher than 7.5 μg / ml, there are problems such as a decrease in survival rate.
[0011]
Moreover, it is desirable that the treatment time of the eye egg with povidone-iodine is 20 minutes to 1 hour. If the treatment time is within 20 minutes, a sufficient sterilizing effect cannot be obtained, and if the treatment time is 1 hour or longer, the survival rate is reduced.
[0012]
The breeding tank according to the present invention is a tank used for breeding ordinary sweetfish, and the material thereof is not particularly limited, such as concrete and FRP. Algae and bottom mud are attached to the walls and bottom of the rearing tank once used, so it is necessary to remove them first using a brush or high-pressure washing machine and dry them thoroughly.
[0013]
Next, the concentration of the sodium hypochlorite solution sprayed on the walls and bottom of the breeding tank can be appropriately selected within the range of 0.005 to 0.015% by mass as the effective chlorine concentration. When the concentration is lower than 0.005% by mass, a sufficient bactericidal effect cannot be obtained, and conversely, even if the concentration is higher than 0.015% by mass, the corresponding effect cannot be obtained.
[0014]
The density | concentration of the sodium hypochlorite solution with which the breeding water tank which concerns on this invention is filled can be suitably selected in the range of 0.005-0.015 mass% as an effective chlorine density | concentration. When the concentration is lower than 0.005% by mass, a sufficient bactericidal effect cannot be obtained. Conversely, even when the concentration is higher than 0.015% by mass, an effect commensurate with it cannot be obtained. By circulating the sodium hypochlorite solution for 1 to 2 days in a breeding aquarium equipped with water turbines and other attached facilities, an effective sterilizing effect for all breeding environments can be expected.
[0015]
Thereafter, the sodium hypochlorite solution is neutralized with sodium thiosulfate and drained, and the breeding water is filled after emptying the breeding tank once. That is, in order to prevent an emergency situation due to the remaining sodium hypochlorite, after draining the breeding water again, the egg or larvae are accommodated. The breeding water is not particularly limited, such as normally used ground water or river water, but must be water that does not contain at least pathogenic bacteria that cause Pseudomonas disease, cold water disease, and vibrio disease. If there is a possibility that these pathogens are contained, it is necessary to sterilize water in advance with ultraviolet rays or ozone.
[0016]
Thereafter, breeding can be performed with a normal feed system. For example, it is possible to feed rotifer as an initial feed and shift to artemia or mixed feed according to the growth stage. During the breeding period until the larvae become adults and are shipped, several fish are picked up regularly, and the PCR method (polymerase chain reaction method) is used to quickly diagnose the presence or absence of a fish disease. If an infection occurs, it can be dealt with immediately.
[0017]
【Example】
The following examples further illustrate the present invention.
[0018]
[Example 1]
100 ml of a commercially available povidone-iodine solution was placed in a 200-liter FRP water tank and diluted with 200 l of water to prepare a povidone-iodine solution having an effective iodine concentration of about 5.0 μg / ml. Ayu artificial fertilized eggs were treated by immersing the ovaries on which the egg was attached for 1 hour.
[0019]
[Example 2]
A 10 kl square concrete breeding tank was washed with a deck brush and dried for one week. Next, a sodium hypochlorite solution obtained by diluting 80 ml of a sodium hypochlorite solution having an effective chlorine concentration of 12% by mass with 100 l of water was sprayed on the walls and bottom of the breeding tank and left for 2 days. 8 kl of the breeding water and 6.4 l of the sodium hypochlorite solution were poured into the breeding aquarium, and the water wheel and all other attached equipment were installed, and the breeding water was circulated for two days. After neutralization with sodium thiosulfate, drain and drain the aquarium, and in order to ensure the safety of the fish, in addition, inject at least 8 kl of breeding water that does not contain Pseudomonas disease, cold water disease, or Vibrio disease. Circulating half-day, draining, and again laying ovaries with the treated egg with povidone-iodine solution obtained in Example 1 were housed in a breeding aquarium where 8 kl of the breeding water was poured.
[0020]
After about 6 months, the animals were kept on a normal feed system (rotifer → artemia → mixed feed) and regularly tested for fish disease by PCR (polymerase chain reaction method), but cold water disease, Pseudomonas disease or vibrio The disease did not occur at all, and the breeding result was very good. Therefore, it was confirmed that the sweetfish breeding method of the present invention is effective.
[0021]
【The invention's effect】
By the method of the present invention, it becomes possible to prevent the occurrence of fish diseases that significantly lower the survival rate and reduce the commercial value in the ayu culture process, and contribute to stable seedling production and aquaculture. It has become possible.

Claims (1)

In the method for raising sweetfish, the sodium hypochlorite solution having an effective chlorine concentration of 0.005 to 0.015% by mass is sprayed on the walls and bottom of the dried breeding tank, and then the sodium hypochlorite solution is put in the breeding tank. The water tank and all the other attached equipment are installed, and the sodium hypochlorite solution is circulated for 1 to 2 days to treat the breeding aquarium in which the water wheel and all the other attached equipment are installed, The sodium hypochlorite was neutralized with sodium thiosulfate, then drained, and at least filled with water that did not contain Pseudomonas disease, cold water disease, or Vibrio disease pathogen, drained, and again filled with water that did not contain the pathogen Thereafter, the ayu was treated by immersing it in a povidone-iodine solution diluted to an effective iodine concentration of 2.5 to 7.5 μg / ml for 20 minutes to 1 hour. Ayu method breeding, which comprises rearing houses the larval fish hatched from eyed eggs.