Feed for juvenile fish

Abstract

To provide juvenile fish which is easily stored.SOLUTION: Feed for juvenile fish 1 includes a carrier 2 with a dormant ciliate carried thereon. According to such a configuration, since the dormant ciliate has environmental stress resistance, the feed for juvenile fish 1 can be stored in an environment having great change in temperature and in a dry state and does not require special management. This eases storage of the feed for juvenile fish 1.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to feed for juvenile fish. [Background technology]

[0002] Live bait containing microorganisms such as paramecium is sold as feed for young fish (e.g., Non-Patent Document 1). Because such live bait is in an active state, there is a risk that it may be completely wiped out depending on the storage environment. Therefore, there is a problem that it is difficult for beginners in raising young fish to handle live bait. [Prior art documents] [Patent documents]

[0003] [Non-Patent Document 1] Product name: "Paramecium Mix", manufactured by Charm Co., Ltd., searched on October 24, 2023, Internet<URL:https: / / www.shopping-charm.jp / product / 2c2c2c2c-2c2c-2c2c-2c2c-343430363430> Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present disclosure is to provide feed for juvenile fish that is easy to store. [Means for solving the problem]

[0005] The feed for juvenile fish includes a carrier on which dormant ciliate protozoa are supported.

[0006] According to this configuration, since the dormant ciliate has resistance to environmental stress, the fry feed can be stored in an environment with large temperature changes or in a dry state without requiring special management, which makes it easy to store the fry feed. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a perspective view showing feed for juvenile fish according to this embodiment. [Diagram 2] FIG. 2 shows the survival rate of the larvae two weeks after hatching. [Diagram 3] FIG. 3 shows the growth rate of the needles one month after hatching. [Figure 4] FIG. 4 shows the number of microorganisms contained in 10 μL of water three days after the larval fish feed was submerged in the aquarium. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] <Feed for young fish> Hereinafter, the fry feed 1 will be described with reference to Fig. 1. Fig. 1 is a perspective view showing the fry feed 1 according to this embodiment. A part of a container 3, which will be described later, is omitted in Fig. 1. As shown in Fig. 1, the fry feed 1 is used by being put into a breeding container for fry. Examples of fry include extremely small fry that have difficulty eating brine shrimp or daphnia, such as killifish that are about two weeks old after hatching and betta fish that are about one week old after hatching.

[0009] The fry feed 1 includes a support 2 carrying dormant ciliate protozoa. With this configuration, the fry feed 1 can be stored in an environment with large temperature changes or in a dry state, and no special care is required for the fry feed 1. This makes it easy to store the fry feed 1. In addition, since no special care is required, the transportation costs of the fry feed 1 can be reduced. Furthermore, since the fry feed 1 is live bait, the water in the rearing container will not be polluted even if too much of the fry feed 1 is given to the fry. The support 2 may carry microorganisms other than ciliate protozoa.

[0010] The ciliate is preferably a soil ciliate that lives in soil. In an aqueous environment suitable for proliferation, the soil ciliate becomes a proliferative cell that swims using cilia. In an environment unsuitable for survival, such as the disappearance of puddles, the soil ciliate becomes a dormant cell (dormant cyst) that is resistant (environmental stress resistance) to drying, ultraviolet light, freezing, high temperature, acid, etc. The dormant ciliate refers to a ciliate that has become a dormant cell.

[0011] Examples of ciliate protozoa include those belonging to the order Colpoda and Nathura, etc. Specific examples include those belonging to the genera Colpoda, Apocolvoda, Breslaua, Hausmanniiella, Mycterocerix, Marina, Bardelliella, Glandoria, Nasula, Fulgasonia, and Paranasula.

[0012] The support 2 is preferably a porous body. This allows the support 2 to support the ciliate and purify the water in the breeding container. In this embodiment, the support 2 is formed in a spherical shape, but is not limited to this.

[0013] The support 2 is preferably cellulose particles (porous cellulose particles). With this configuration, the number of ciliate protozoa supported can be increased compared to when the ciliate protozoa are supported on pumice or wool mat. Furthermore, the cellulose particles of the support 2 assist the proliferation of bacteria that serve as food for the ciliate protozoa, and the ciliate protozoa can be effectively increased. Note that the support 2 is not limited to the above, and may be, for example, pumice, wool mat, ceramic, activated carbon, or the like.

[0014] The outer diameter (size) of the support 2 is preferably 1 mm or more. This ensures water permeability of the container 3 described below and prevents the support 2 (feed for fry 1) from falling out of the container 3. The outer diameter (size) of the support 2 is preferably 5 mm or less. This makes it possible to prevent gaps from being generated within the container 3 and ensures the number of supports 2 that can be contained in the container 3 (the number of ciliates that can be supported).

[0015] The fry fish feed 1 (support 2) is preferably contained in a water-permeable container 3. This configuration can prevent the fry fish feed 1 from scattering in the breeding container. This makes it easy to collect and replace the fry fish feed 1. The size of the water-passing holes in the container 3 is 100 μm or more. This allows the activated ciliates to pass through the water-passing holes and exit the container 3.

[0016] The container 3 is preferably formed in a mesh (net) shape. This allows the activated ciliate to spread quickly throughout the rearing water. In this embodiment, the fry feed 1 is enclosed in the container 3, but is not limited to this. For example, the container 3 may be configured such that the fry feed 1 contained therein can be taken out.

[0017] The container 3 is preferably made of a material that does not affect the water quality in the breeding container, such as polyester, nylon, or polyethylene.

[0018] The container 3 can accommodate, for example, 10 mL to 30 mL of the fry feed 1 (support 2). In this embodiment, the container 3 can accommodate 20 mL of the fry feed 1 (support 2), but is not limited to this.

[0019] <Manufacturing method for feed for young fish> An example of a method for producing feed for juvenile fish will be described. Note that the present invention is not limited to the following production method, and juvenile fish feed produced by methods and conditions other than those described below is also included in the present invention.

[0020] (Culture process) First, the dormant ciliates attached to the rice stalks are placed in a culture solution, and the ciliates that resume activity within the solution are cultured. Specifically, 80 L of water, which serves as the culture solution, is placed in a 100 L first tank (bucket), and dried rice stalks placed in a net are placed into the culture solution, and the ciliates are cultured for 24 hours with the rice stalks submerged.

[0021] Then, 12 hours after the start of the culture, calcium chloride (50 mg / L) is added to the culture solution to increase the calcium ion concentration in the culture solution and put active ciliates into a dormant state. When ciliates (e.g., Colpoda) receive environmental changes (increases in calcium ion concentration and cell density in the environment due to increases in water temperature and evaporation of water) as a desiccation prediction signal, they quickly go into a dormant state to protect themselves from desiccation. In this embodiment, the culture process was carried out at a room temperature of 23°C and with the culture solution constantly aerated.

[0022] (filtration process) Next, the culture solution in the first tank is filtered through a 100 μm mesh, and the filtered culture solution is transferred to the second tank. By filtering the culture solution, organisms that prey on the ciliate can be eliminated.

[0023] (Supporting process) Next, the dormant ciliate is supported on a support. Specifically, 50 L of cellulose particles (Viscopal (registered trademark)) as a support was added to 80 L of the culture solution filtered in the filtration process, and left for 24 hours. In this embodiment, the culture process was performed at room temperature of 23°C, with the culture solution constantly aerated. By supporting the dormant ciliate on a support, it is possible to suppress the variation in the number of ciliate supported on each support. This is because the ciliate is dormant and does not move on its own.

[0024] (drying process) Next, the support is pulled out from the second tank and dried for one week. In the drying process, the support 2 is dried indoors (at room temperature of 23° C. in this embodiment). This allows the feed for juvenile fish according to this embodiment to be produced.

[0025] (Containment process) In this embodiment, the produced feed for juvenile fish is stored in a storage body. In the storage step, 20 mL of feed for juvenile fish is stored in the storage body. EXAMPLES

[0026] In order to specifically show the effects of the feed for juvenile fish, examples and comparative examples of the feed for juvenile fish will be described with reference to Figs. 2 to 4.

[0027] <Example> As an example, feed for juvenile fish was produced using the above-mentioned production method.

[0028] <Needlework Training Test 1> Two breeding containers containing 10 L of water (dechlorinated tap water) were prepared, and 55 medaka fry (fry) were hatched in each breeding container. One was fed only artificial feed (Medaka Genki Powder Food made by GEX), while the other was fed the artificial feed and fry feed (20 mL), and the fry in each breeding container were raised for two weeks after hatching.

[0029] Figure 2 shows the survival rate of the larvae two weeks after hatching. As shown in Figure 2, the survival rate of the larvae fed only artificial feed was 5.5%, while the survival rate of the larvae fed artificial feed and larval feed was 36.4%.

[0030] <Needlework Training Test 2> Six breeding containers containing 700 mL of water (dechlorinated tap water) were prepared, and five medaka fry (fry) were hatched in each breeding container. The fry in three breeding containers were fed only artificial food (Medaka Genki Powder Food manufactured by GEX), while the fry in the other three were fed the artificial food and fry food (20 mL). The fry in each breeding container were raised for one month after hatching.

[0031] Figure 3 shows the growth rate of the larvae one month after hatching. As shown in Figure 3, the growth rate of the larvae fed only artificial feed was about 40.9%, while the growth rate of the larvae fed artificial feed and fry feed was 51.3%. From the larvae rearing tests 1 and 2, it was confirmed that the fry feed is suitable for rearing fry.

[0032] <Comparative Example 1> As Comparative Example 1, a wool mat was used as the carrier, and feed for juvenile fish was produced by the above-mentioned production method.

[0033] <Comparative Example 2> As Comparative Example 2, pumice was used as the carrier and feed for juvenile fish was produced by the above-mentioned production method.

[0034] <Support test> Three tanks containing 500 mL of water (dechlorinated tap water) were prepared. Then, 20 mL of the fry feed according to the Example, Comparative Example 1, and Comparative Example 2 was placed in different containers, and each fry feed was submerged in a different tank and left for three days.

[0035] After three days, three 10μL drops of water from each tank were placed on a slide and observed under an optical microscope (magnification: 40x or 100x). The number of microorganisms, including ciliates, in each drop (10μL) was then counted.

[0036] Fig. 4 is a diagram showing the number of microorganisms contained in 10 μL of water three days after the fry feed was submerged in an aquarium. In Fig. 4, the number of microorganisms is shown as the average value for each drop. As shown in Fig. 4, the number of microorganisms contained in 10 μL of water was 2.5 in Comparative Example 1, approximately 8.2 in Comparative Example 2, and 11.5 in the Example. This confirmed that cellulose particles are suitable as a support for supporting microorganisms (ciliates).

[0037] <How to use feed for young fish> When the fry feed is poured into the rearing container, the ciliates become active and multiply after about two days. Therefore, it is possible to culture the ciliates in the rearing container, and there is no need to prepare a separate culture container. By pouring the fry feed into the rearing container shortly before the fry hatch (two days to one week before), the fry can be fed the ciliates immediately after hatching. In the case of a rearing container with a capacity of 10 L or less, it is preferable to pour in 20 mL of fry feed. The recommended replacement interval for fry feed is, for example, two months.

[0038] [1] As described above, the feed for juvenile fish 1 according to this embodiment includes the support 2 on which dormant ciliate protozoa are supported.

[0039] According to this configuration, since the dormant ciliate has resistance to environmental stress, the fry feed 1 can be stored in an environment with large temperature changes or in a dry state, and no special management is required. This makes it easy to store the fry feed.

[0040] [2] In the feed for fry 1 according to the above item [1], the support 2 is preferably a cellulose particle.

[0041] With this configuration, the number of ciliate protozoa can be increased compared to when the ciliate protozoa are supported on pumice or wool mat. Also, the cellulose particles of the support 2 support the proliferation of bacteria that serve as food for the ciliate protozoa, and the ciliate protozoa can be effectively increased.

[0042] [3] The fry feed 1 according to the above-mentioned [1] or [2] is preferably contained in a container having water permeability.

[0043] This configuration can prevent the fry feed 1 from scattering in the rearing container, which makes it easy to collect and replace the fry feed 1. In addition, by making the container 3 into a mesh shape, the activated ciliates can be quickly distributed throughout the rearing water.

[0044] The fry feed 1 of the present disclosure is not limited to the above-mentioned embodiment, and is not limited to the above-mentioned action and effect. The fry feed 1 of the present disclosure can be improved or modified in various ways without departing from the gist of the present disclosure. In addition, the configurations employed in the above-mentioned embodiment can be combined in any desired manner. [Explanation of symbols]

[0045] 1. Feed for young fish 2...Support body 3. Containment Unit

Claims

1. A feed for fry comprising a carrier carrying dormant ciliate protozoa.

2. The feed for juvenile fish according to claim 1 , wherein the support is a cellulose particle.

3. The feed for fry according to claim 1 or 2, which is contained in a container having water permeability.

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