TW202226957A - Feed composition for zooplankton, method for producing zooplankton, zooplankton, method for producing aquatic organism, and additive for water for raising aquatic organism - Google Patents

Abstract

The present invention provides: a zooplankton feed composition that contains algae belonging to the class Cyanidiophyceae; a zooplankton production method comprising feeding zooplankton with the zooplankton feed composition; a method that is for producing an aquatic organism and that comprises feeding the aquatic organism with zooplankton produced by the zooplankton production method; zooplankton grown by being fed with the zooplankton feed composition; and an additive that is for water for raising an aquatic organism and that comprises algae belonging to the class Cyanidiophyceae.

Description

Feed composition for zooplankton, production method of zooplankton, production method of zooplankton, aquatic organisms, and additives for aquatic organisms breeding water

The present invention relates to a feed composition for zooplankton, a method for producing zooplankton, a method for producing zooplankton and aquatic organisms, and an additive for aquatic organism breeding water. This application claims priority based on Japanese Patent Application No. 2020-169275 for which it applied in Japan on October 6, 2020, and the content is incorporated herein by reference.

In aquaculture, zooplankton such as rotifers and daphnia are used as early feed for fish and shellfish (live feed for larvae and juveniles just hatched from eggs). Freshwater chlorella is generally used as a feed for zooplankton (Patent Document 1). Freshwater Chlorella commercially available as zooplankton feed is a concentrated solution of living Chlorella.

Chlorella concentrate needs to be refrigerated at 4°C to prevent the reproduction and spoilage of microorganisms. The storage time is as short as 1 month from the date of manufacture. Therefore, it is difficult to use in developing countries where refrigeration equipment is not perfect, and long-distance transportation such as overseas transportation is also difficult. In addition, the cost of refrigerated storage is relatively high. In addition, commercially available freshwater Chlorella generally contains about 10 ⁸ cfu/mL of bacteria, so the larvae and juveniles with immature immune mechanisms are at high risk of developing infectious diseases. Furthermore, since freshwater chlorella is a freshwater alga, it cannot survive in seawater. Therefore, in the case of use in a marine fish farm, there is a problem that the remains of freshwater chlorella are corrupted and the water quality is deteriorated. [Prior Art Literature] [Patent Literature]

[Patent Document 1] International Publication No. 2010/089864

[The problem to be solved by the invention]

As described above, freshwater chlorella, which is commonly used as a feed for zooplankton, has problems such as storage stability. Therefore, in the field of aquaculture, there is a need for a zooplankton feed that can be stored at room temperature, has few miscellaneous bacteria, and can survive in both freshwater and seawater.

Therefore, an object of the present invention is to provide a zooplankton feed composition which has few miscellaneous bacteria, is excellent in storage stability, and can be used in both fresh water and sea water, a zooplankton production method using the above zooplankton feed composition, and The produced zooplankton, the production method of aquatic organisms using the above-mentioned zooplankton, and the water additive for aquatic organism breeding. [Technical means to solve the problem]

The present invention includes the following aspects. [1] A feed composition for zooplankton, which comprises Cyanidiophyceae algae. [2] The zooplankton feed composition according to [1], wherein the hot spring red algae is an alga belonging to the genus Galdieria. [3] A method for producing zooplankton, comprising: feeding the zooplankton with the zooplankton feed composition described in [1] or [2]. [4] A zooplankton that is proliferated by feeding the zooplankton feed composition described in [1] or [2]. [5] A production method for aquatic organisms, comprising: feeding aquatic organisms with zooplankton produced by the zooplankton production method described in [3]. [6] A water additive for aquaculture of aquatic organisms, which comprises hot spring red algae. [7] The additive for aquatic culture water according to [6], wherein the above-mentioned hot spring red algae is a unicellular red algae. [Effect of invention]

According to the present invention, there are provided a zooplankton feed composition with few miscellaneous bacteria and excellent storage stability, which can be used in both fresh water and seawater, a zooplankton production method using the above-mentioned zooplankton feed composition, and the produced zooplankton feed composition. Zooplankton, production method of aquatic organisms using the above-mentioned zooplankton, and additives for aquatic organisms.

<Feed composition for zooplankton> The first aspect of the present invention is a feed composition for zooplankton, which contains hot spring red algae.

(Hot Spring Red Algae) As unicellular primitive red algae, the hot spring red algae are the algae that preferentially proliferate in sulfuric acid hot springs. It is known that there are primitive red algae (Cyanidioschyzon), high temperature red algae (Cyanidium), and unicellular red algae in the class of hot spring red algae. Cyanidioschyzon merolae is mentioned as an alga of the genus Rhododendron, but it is not limited to this. Examples of the unicellular red algae include G.sulphuraria, G.partita, G.daedala, and G.maxima, but are not limited thereto. As the algae of the genus Rhodophyta, for example, C. caldarium, C. sp. Monte Rotaro and the like may be mentioned, but not limited thereto. As an algal strain of the class of hot spring red algae, other than the above, for example, those described in FIG. 10 of International Publication No. 2019/107385 can be mentioned.

The hot spring red algae can be cultivated in the pH value of about 1 to 4 with relatively high acidity. Therefore, it is possible to suppress the growth of miscellaneous bacteria such as general bacteria that inhabit the neutral vicinity by culturing under a culture condition with a high acidity of pH 1 to 4 (preferably pH 2 to 3). In addition, since the hot spring red algae can be cultivated at a high temperature of about 40 to 50 °C, it can be stably stored in a wide temperature range of 0 to 40 °C. In addition, since heterotrophic culture is possible, it can be stably stored in the dark. In addition, hot spring red algae can survive in both freshwater and seawater. Therefore, it can be used in both freshwater fish and marine fish farms, and the dead and corrupt algae will not deteriorate the water quality. Furthermore, as shown in the examples to be described later, hot spring red algae can proliferate zooplankton in the same way as freshwater Chlorella vulgaris. In addition, among the hot spring red algae, especially the unicellular red algae, they are resistant to desiccation, so they can also be stored in a dry state. Due to the above-mentioned characteristics, hot spring red algae are suitable for use as zooplankton feed with high storage stability.

The hot spring red algae algae used in the feed composition of this aspect may be any one of the algae of the genus Primal Rhododendron, the algae of the genus Rhododendron unicellular, and the algae of the genus Rhodophyta. Among them, from the viewpoints of high storage stability and excellent zooplankton growth rate, unicellular red algae algae are preferred, and G. sulphuraria is more preferred.

The hot spring red algae algae used in the feed composition of this aspect can be prepared by culturing using a known medium as a medium for unicellular algae. The medium for unicellular algae is not particularly limited, and examples thereof include inorganic salt medium containing nitrogen source, phosphorus source, trace elements (zinc, boron, cobalt, copper, manganese, molybdenum, iron, etc.). For example, as a nitrogen source, an ammonium salt, a nitrate, a nitrite, etc. are mentioned; As a phosphorus source, a phosphate etc. are mentioned. Examples of such a medium include Gross medium, 2×Allen medium (Allen MB. Arch. Microbiol. 1959 32: 270-277.), M-Allen medium (Minoda A et al. Plant Cell Physiol. 2004 45 : 667-71.), MA2 medium (Ohnuma M et al. Plant Cell Physiol. 2008 Jan; 49 (1): 117-20.), and modified M-Allen medium, etc., but not limited thereto.

Red algae in hot springs can be independently vegetatively cultured under light irradiation or heterotrophically cultured in the dark. In the case of heterotrophic culture, a carbon source (glucose, etc.) can also be added to the inorganic salt medium as described above.

The medium for culturing hot spring red algae may be a liquid medium or a solid medium, but a liquid medium is preferable from the viewpoint of being able to cultivate in large quantities.

The culturing conditions are not particularly limited, and those generally used as culturing conditions for hot spring red algae can be used. The culture conditions include, for example, pH 1 to 8, temperature of 10 to 50°C, and CO ₂ concentration of 0.3 to 3%. Regarding light conditions, in the case of performing heterotrophic culture, the culture can be performed in a dark place. In the case of independent nutrient culture, for example, 5 to 2000 μmol/m ² s can be mentioned.

In order to be able to inhibit the propagation of miscellaneous bacteria, the culturing conditions are preferably carried out in an acidic condition with a pH value of about 1 to 4, more preferably a pH value of 1 to 3, and still more preferably a pH value of 2 to 3. As the culture conditions for good proliferation of red algae in hot springs, for example, pH value of 2 to 3, temperature of 30 to 40°C, and CO ₂ concentration of 0.3 to 3% can be mentioned.

The hot spring red algae contained in the feed composition of this aspect may be living cells or dead cells. The living cells of red algae in hot springs can be in the form of a concentrated solution suspended in a culture medium, etc., or in the form of a cell pellet obtained by centrifuging or filtering the culture medium, or in the form of a cell pellet obtained after removing water. The obtained dried body.

Dead cells of the hot spring red algae may be cell ruptured, and may also be, for example, dry powder. The dry powder of hot spring red algae can be obtained, for example, by collecting cells from the culture solution of hot spring red algae by centrifugation, filtration, etc., and drying by natural drying, freeze drying, or warm drying, etc. . In addition, after drying, the algal body may be physically broken to obtain a finer powder. From the viewpoint of making the reproduction rate of zooplankton good, the hot spring red algae are preferably living cells. By feeding in the form of live feed, the hot spring red algae can be proliferated in the culture water of zooplankton, and supplied as the feed of zooplankton.

(Other ingredients) The feed composition of this aspect may contain other ingredients in addition to hot spring red algae. Other components are not particularly limited, and known ones can be used as components of the feed composition. Examples of other components include medium components of hot spring red algae, nutrient-enhancing components for enhancing the nutritional value of zooplankton and aquatic organisms, dry powder of other fine algae such as chlorella, and the like. Examples of nutritional enhancement components include amino acids, vitamins, minerals, fatty acids (eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and docosapentaenoic acid), for example. alkenoic acid (DPA), etc.), etc.

The feed composition of this aspect can be used for feeding zooplankton to breed zooplankton. The so-called "plankton" is a general term for the tiny organisms that float and live in the water. The so-called "zooplankton" is a general term for plankton that does not perform photosynthesis but feeds on organic matter such as phytoplankton to obtain nutrients. The feeding objects of the feed composition of this aspect are zooplankton, especially those used as feed for fish and shellfish in the production of seedlings or breeding, etc. are preferred. Examples of such zooplankton include rotifers, brine shrimp, copepods, and water fleas. Rotifers belong to the phylum of rotifers, such as Brachionus plicatilis and B.rotundiformis. Brine shrimps belong to the phylum Crustacea of Arthropoda, such as Artemia salina. Copepods and Daphnia belong to the phylum Arthropoda. The feed composition of this aspect is especially suitable for rotifers.

(Preservation method) Since the feed composition of this form uses hot spring red algae, it does not need to be refrigerated even in the state of live bait. When the feed composition of this aspect contains live cells of the hot spring red algae, it is preferable to store it in the form of a concentrated solution in which the live cells of the hot spring red algae are suspended in the medium. In this case, the pH of the feed composition is preferably pH 1-4, more preferably pH 2-3. By setting it as the said pH value range, the growth of various bacteria can be suppressed, and storage stability can be improved.

The storage temperature of the feed composition of this aspect can be set to, for example, 0 to 40°C, 10 to 40°C, 20 to 40°C, or 25 to 40°C. By setting the pH of the feed composition to pH 1 to 4 (preferably pH 2 to 3), good quality can be maintained even without refrigeration (4°C).

Preservation can be carried out in a bright place or in a dark place.

<Method for producing zooplankton> The second aspect of the present invention is a method for producing zooplankton, comprising feeding the zooplankton with the zooplankton feed composition of the first aspect (hereinafter, also referred to as "feed composition"). thing").

The zooplankton produced by the production method of this aspect is preferably used as a feed for fish and shellfish in the production of seedlings or cultivation, etc., and the same zooplankton as exemplified in the above-mentioned <Feed composition for zooplankton> can be exemplified .

The zooplankton can be cultured by a known method depending on the species. As the culture water, seawater, artificial seawater, or fresh water can be used according to the species of zooplankton. Fill a culture tank of appropriate capacity with culture water, inoculate zooplankton and start culture. The inoculation density is not particularly limited, but can be set to, for example, 5 to 50 individuals/mL or the like. The temperature conditions of zooplankton are not particularly limited and can be selected according to the species. As temperature conditions, 10-35 degreeC etc. are mentioned, for example. In addition, aeration may be appropriately performed using a pump or the like during the culture. The culturing conditions of the zooplankton are preferably set to conditions close to the culturing conditions of the aquatic organisms feeding the zooplankton. By making the culture conditions of zooplankton close to those of aquatic organisms, it is possible to suppress the death of zooplankton after feeding, and to suppress the deterioration of the quality of the culture water.

The feeding method of the zooplankton feed composition is not particularly limited. When the pH value of the feed composition is acidic (about pH 1 to 4), the pH value can also be adjusted to be close to the pH value of the culture water of zooplankton before feeding. By making the pH value of the feed composition close to the pH value of the zooplankton culture water, the pH change of the zooplankton culture water due to feeding can be suppressed. The pH value can be adjusted by adding a pH value adjuster, or by removing the medium containing the feed composition by centrifugation or filtration, etc., so that the algae of the hot spring red algae are resuspended in the medium with the required pH value. make adjustments.

The culture of zooplankton can be continuous culture or batch culture. The so-called continuous culture refers to a culture method in which culture water and feed are continuously supplied to the culture tank, and zooplankton are continuously harvested. The so-called batch culture refers to the culture method of discontinuous supply of culture water and feed, feeding and subculture at the appropriate time. In the case of batch culture, the feeding frequency of the feed composition can be set to, for example, about 1 to 3 times a day, and the frequency of subculture can be set to, for example, about once every 2 to 7 days.

The feeding amount of the feed composition is not particularly limited, and can be appropriately adjusted according to the density of zooplankton in the culture water and the amount of feed residues. For example, the feeding amount can be adjusted in such a way that the density of the red algae in the hot springs in the culture water reaches 500,000 to 8,000,000 cells/mL.

In the zooplankton production method of this aspect, the zooplankton feed composition of the first aspect is fed to the zooplankton. Since the hot spring red algae contained in the above feed composition can survive in both seawater and freshwater, even when the culture water of zooplankton is either seawater or freshwater, they can also survive in the culture water. Therefore, it is possible to suppress deterioration of water quality caused by the decay of the remains of the algal body. In addition, in the zooplankton feed composition of the first aspect, the number of bacteria in the composition can be kept low by using hot spring red algae prepared under acidic conditions. Therefore, when the zooplankton is used in the case of larvae and juveniles with immature immune mechanisms, the mixing of bacteria into the culture water of larvae and juveniles can also be suppressed, and the risk of fish diseases can be reduced.

<Zoplankton> The third aspect of the present invention is a zooplankton that has been fed with the zooplankton feed composition of the first aspect and has grown.

The zooplankton of this aspect can be obtained by the above-mentioned production method of the zooplankton of the second aspect. Since the zooplankton in this form proliferate in the culture water with good water quality and the bacteria are less mixed, it is suitable to be used as feed for fish and shellfish in the production of seedlings or aquaculture.

<Method for producing aquatic organisms> The fourth aspect of the present invention is a method for producing aquatic organisms, comprising: feeding the aquatic organisms with the zooplankton produced by the method for producing zooplankton in the second aspect above (hereinafter. Also referred to as "zooplankton").

"Aquatic organisms" refer to organisms that live in or near water (aquatic organisms), and are industrially used organisms. Examples of aquatic organisms include, but are not limited to, fish, crustaceans, and shellfish. Aquatic organisms may be marine organisms or freshwater organisms. The aquatic organism is preferably a fish, more preferably a marine fish.

The feeding of zooplankton is preferably carried out within a certain period of time after the initiation of feeding action after the hatching of aquatic organisms. For example, where the aquatic organisms are fish, the zooplankton may be fed during part or all of the larval stage. For example, where the aquatic organisms are crustaceans, the zooplankton may be fed for part or all of the larval period. The frequency of feeding is not particularly limited, but may be set to about 1 to 5 times a day, for example. The feeding amount is not particularly limited, and can be appropriately adjusted according to the growth and development status of the larvae and juveniles in the breeding water and the amount of zooplankton residues.

The method of culturing aquatic organisms is not particularly limited, and methods commonly used in the production of seedlings or culturing of aquatic organisms can be used. In the case where the aquatic organism is a fish, for example, fertilized eggs are obtained by fertilizing eggs collected from a female fish. Fill a culture tank with appropriate capacity with culture water, so that the above-mentioned fertilized eggs float or sink, and the fertilized eggs hatch. Larvae become able to feed on zooplankton about 1 to 2 days after hatching. At this point, zooplankton can be fed. The aquaculture water for larvae and juveniles may use seawater, artificial seawater, or freshwater according to the species of fish.

After the feeding period of zooplankton is over, the breeding tank and feed can be appropriately changed according to the growth stage of aquatic organisms to continue breeding. The aquatic organisms produced by the production method of this aspect may be juveniles or larvae produced by seedling production, or may be adults obtained by further culturing them.

<Additive for aquaculture water> The fifth aspect of the present invention is an additive for water for aquaculture, which contains hot spring red algae.

Regarding the production of seedlings and the like, aquatic organisms are present in aquaculture water in an excessively dense manner compared to the natural world. Therefore, when the transparency of the culture water is too high, the pressure on aquatic organisms may increase. The additive for aquaculture of aquatic organisms in this aspect can be used to color the aquaculture water to reduce the transparency, so as to ease the pressure on aquatic organisms.

Since the additive for aquatic organism culture water of this aspect contains hot spring red algae, if it is added to the culture water of aquatic organisms, the culture water will appear green and the transparency will be reduced. The amount added to the aquaculture water is not particularly limited, as long as it is added in an amount that will appropriately develop the color of the aquaculture water.

This aspect of the additive for aquaculture water for aquatic organisms is especially suitable for use in aquaculture water for larvae and juveniles. Since the hot spring red algae algae contained in the water additive for aquatic organism culture of this aspect is the feed for the zooplankton fed to the larvae, the zooplankton can be proliferated in the culture water. Thereby, the feeding amount of zooplankton can be reduced.

The hot spring red algae algae contained in the aquatic organism breeding water additive of this aspect may be living cells or dry powder, but preferably living cells. By using living cells, deterioration of water quality caused by spoilage can be suppressed. Moreover, since it can multiply in aquaculture water, it can multiply zooplankton in aquaculture water efficiently. Since the hot spring red algae algae contained in the additive for aquaculture water of this aspect can survive in both seawater and freshwater, even if the aquaculture water for aquatic organisms is either seawater or freshwater, living cells can be used as additive.

In addition, the additive for aquatic life culture water of this aspect has high storage stability by preparing hot spring red algae under acidic conditions, so that refrigeration storage is not required. Furthermore, since the number of bacteria mixed in is also small, it can also be used in the breeding water of larvae and juveniles, and there is no risk of fish disease. Example

Hereinafter, the present invention will be described using examples, but the present invention is not limited to the following examples.

<Example 1: Storage stability test> (Preparation of hot spring red algae) Galdieria sulphuraria CCC ryo127-00 strain (hereinafter also referred to as "Galdieria") was used for the hot spring red algae. In a 500 mL Erlenmeyer flask, add 300 mL of Gross medium (pH 2) supplemented with 1 mass % glucose to carry out heterotrophic culture of Galdieria. When the Galdieria reached the stationary phase, the Gross medium stock solution was added to the culture medium in such a way that the concentration of each component in the culture medium reached 3 times that of the Gross medium, and independent nutrient culture was carried out for 7 days. For both heterotrophic culture and independent nutrient culture, the culture temperature was set at 40 °C and the shaking speed was set at 125 rpm. After 7 days of independent nutrient culture, in order to increase the concentration of algae, the culture medium was centrifuged at 3000 rpm at 25°C for 5 minutes. After centrifugation, the supernatant was discarded, an appropriate amount of Gross medium (pH value 2) was added, and a part thereof was taken to measure the dry weight. Based on the measured dry weight, a concentration of Galdieria was prepared by adding Gross medium (pH 2) in such a way that the dry weight reached 7 g/L. The composition of Gross medium is shown in Table 1. In addition, the compositions of the Fe-EDTA solution and trace elements (Trace Elements) used in the Gross medium are shown in Table 2 and Table 3, respectively.

[Table 1] Gross medium (NH ₄ )2SO ₄ 1.5g MgSO ₄ •7H ₂ O 300 mg KH ₂ PO ₄ 300 mg CaCl ₂ •2H ₂ O 20 mg NaCl 20 mg Fe-EDTA solution 1.5mL trace elements 2.0 mL Adjust to pH _2.0 by adding 2M _H2SO4 H ₂ O 1L

[Table 2] Fe-EDTA solution _FeSO4 690 mg EDTA-2Na 930 mg H ₂ O 100mL

[table 3] trace elements H ₃ BO ₃ 2.86g MnCl ₂ •4H ₂ O 1.82g ZnSO ₄ •7H ₂ O 220 mg (NH ₄ ) ₆ Mo ₇ O ₂₄ 4H ₂ O 30 mg CuSO ₄ •5H ₂ O 80 mg NaVO ₃ •4H ₂ O 40 mg CoCl ₂ •6H ₂ O 40 mg H ₂ O 1 L

(Preparation of control algae) Chlorella vulgaris (hereinafter referred to as "Chlorella") (Chlorella vulgaris for ornamental fish-V12, Chlorella Industry Co., Ltd.) was used as a control algae. Chlorella is an algae traditionally used as feed for rotifers. The chlorella liquid was centrifuged at 2500 rpm for 1 minute at 4°C, and the supernatant was removed. AF6 medium was added, and centrifugation was performed again. This step was repeated three times to wash the chlorella. After that, AF6 medium was added so that the dry weight would be 7 g/L to prepare a chlorella concentrate. The composition of AF6 medium is shown in Table 4. The composition of the P IV metal used in the AF6 medium is shown in Table 5.

[Table 4] AF6 medium NaNO ₃ 14 mg _{NH4NO3 _} 2.2 mg MgSO ₄ •7H ₂ O 3 mg KH ₂ PO ₄ 1 mg K ₂ HPO ₄ 0.5 mg CaCl ₂ •2H ₂ O 1 mg Ferric citrate 0.2 mg citric acid 0.2 mg Biotin 0.2 μg Thiamine HCl 1 μg Vitamin _B6 0.1 μg Vitamin _B12 0.1 μg P IV metal 0.5mL pH adjusted to pH 6.6 H ₂ O 100mL

[table 5] P IV metal Na ₂ EDTA•2H ₂ O 100 mg FeCl ₃ •6H ₂ O 19.6 mg MnCl ₂ •4H ₂ O 3.6 mg ZnSO ₄ •7H ₂ O 2.2 mg CoCl ₂ •6H ₂ O 0.4 mg Na ₂ MoO ₄ •2H ₂ O 0.25 mg H ₂ O 100mL

(Storage stability test) Dispense the Galdieria concentrate and Chlorella concentrate prepared as described above into 50 mL Falcon tubes, each 15 mL, in a culture library at 40°C under two conditions of light and dark. for storage. At the start of storage (day 0) and the second day of storage, the number of cells, dry weight, pH, and number of Vibrio bacteria were measured, and sensory evaluations (appearance, odor) were performed.

Determination of cell number: cells were counted using a hemocytometer. Measurement of dry weight: The concentrated solution was filtered, and the solid content was dried at 105°C for 1 hour, and then the weight was measured. pH value: measured with a pH meter. Number of Vibrio bacteria: The concentrated solution was spread in TCBS Cholera Medium (TCBS Cholera Medium, Thermo Fisher Scientific), and the number of colonies was counted after culturing at 37°C for 27 days. Sensory test (color): Observe the concentrate with the naked eye, and evaluate the color of the concentrate. Sensory test (odor): Open the lid of the 50 mL Falcon tube that dispenses the concentrate, smell the odor of the concentrate, and evaluate the presence or absence of fermentation odor.

The results are shown in Table 6.

[Table 6] Galdieria Chlorella 0 days Day 2 0 days Day 2 Ming place dark place Ming place dark place Number of cells (100 million cells/mL) 4.25 5.05 4.65 5.6 5.55 5.9 Dry weight (g/L) 7 6.1 5.9 7 5.6 5.4 pH 2.16 2.26 2.27 6.15 5.48 5.39 Vibrio count (cfu/mL) <100 <100 <100 <100 2.2×10 ⁶ 5.7×10 ⁵ Sensory test (color) green green green green brown brown Sensory test (odor) none none none none Fermentation smell Fermentation smell

As shown in Table 6, in the case of Galdieria, the number of Vibrio bacteria was maintained at <100 in both bright and dark places. On the other hand, in the case of Chlorella, the number of Vibrio bacteria increased to 10 ⁶ in the bright place, and increased to 10 ⁵ in the dark place. Regarding the color of the concentrate, in the case of Galdieria, it remained green in both light and dark. Also, no fermentation smell was felt. On the other hand, in the case of chlorella, it turned brown in both the light and the dark, and a fermentation smell was felt. These results indicate that Chlorella produces algal decay. Regarding the pH value, in the case of Galdieria, the pH value increased only slightly in both the light and the dark, and basically no change was observed. On the other hand, in the case of Chlorella, a drop in pH was observed both in the light and in the dark. In the case of Chlorella, the pH reduction is believed to be caused by the production of organic acids due to spoilage. In addition, in the case of Galdieria, it was confirmed that general bacteria did not proliferate until the second day.

From the above results, it was confirmed that Galdieria has a small storage stability and is excellent in Chlorella.

<Example 2: Feeding test to zooplankton> (Preparation of hot spring red algae) Galdieria sulphuraria CCC ryo127-00 strain (Galdieria) was used for the hot spring red algae. In a 500 mL Erlenmeyer flask, add 300 mL of Gross medium (pH 2) supplemented with 1 mass % glucose to carry out heterotrophic culture of Galdieria. At the point at which the Galdieria reached stationary phase, the culture broth was centrifuged at 3000 rpm for 5 minutes at 25°C. After centrifugation, the supernatant was discarded, an appropriate amount of Gross medium (pH value 2) was added, and a part thereof was taken to measure the dry weight. Based on the measured dry weight, Gross medium without pH adjustment (pH value 4.6) was added so that the dry weight reached 42 g/L to prepare a Galdieria concentrate.

(Preparation of Control Algae) Chlorella vulgaris (Chlorella vulgaris) (Chlorella vulgaris for ornamental fish-V12, Chlorella Industrial Co., Ltd.) was used as a control algae. The purchased chlorella liquid was directly used as the chlorella concentrate. A part was taken to measure the dry weight, and the measured dry weight was 55 g/L.

(Preparation of zooplankton) Brachionus plicatilis (hereinafter also referred to as "rotifer") was used as the zooplankton. The rotifers were purchased from Ridai Center Co., Ltd. and fed with Chlorella (Chlorella for ornamental fish-V12, Chlorella Industrial Co., Ltd.) for cultivation until use.

(Feeding test) In a 500 mL conical flask, add 500 mL of 70% artificial seawater (RED SEA SALT, 24.5 g/L), and ventilate through a silicon tube. Rotifers were inoculated at a density of 190 individuals/mL and cultured at 27°C. The culture medium was heated in a water bath using a heater to keep the temperature constant. Use Galdieria Concentrate or Chlorella Concentrate 3 times a day. The feeding amount should be adjusted appropriately while observing the residual amount of feed in the culture water. The number of prepared rotifers and the number of egg-carrying individuals were counted 3 times at each breeding time, and the average value was calculated.

The proliferation of rotifers in the feeding test is shown in FIG. 1 . Rotifers fed with Galdieria showed equivalent proliferation as rotifers fed with Chlorella.

Tables 7 and 8 show the daily proliferation rate, egg-carrying individual rate, and daily feeding rate of rotifers in the feeding test. These are calculated according to the following formula. The rotifers are considered to be in good nutritional status if the egg-carrying individual rate is usually more than 20%. Daily proliferation rate (%) = {(the number of rotifers on the day) - (the number of rotifers on the previous day)}/(the number of rotifers on the previous day) × 100 The number of eggs with eggs (%) = (number of rotifers carrying eggs)/(number of rotifers as a whole) × 100 Daily feeding rate (g/1 million individuals) = (feeds fed in 1 day (g))/(rounds Number of insects) × 1 million

[Table 7] Chlorella Culture time (h) Daily proliferation rate (%) Egg carrier rate (%) Daily feeding rate (g/1 million individuals) 0 - 38.6 0.58 twenty four 110.5 34.2 0.55 46 140.8 23.5 0.4 72 50.2 27.4 0.27 92 33.2 17.6 0.20 115 16.8 18.1 -

[Table 8] Galdieria Culture time (h) Daily proliferation rate (%) Egg carrier rate (%) Daily feeding rate (g/1 million individuals) 0 - 44.6 0.59 twenty four 112.5 34.5 0.55 46 117.6 18.1 0.41 72 59.5 25.2 0.28 92 42.6 29.5 0.20 115 29.7 18.2 -

As shown in Tables 7 and 8, the rotifers fed with Galdieria exhibited the same daily proliferation rate and egg-carrying individual rate as those fed with Chlorella. These results indicate that Galdieria is as suitable as Chlorella as a zooplankton feed.

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[Fig. 1] shows the proliferation of Brachionus plicatilis in the feeding test.

Claims (7)

A feed composition for zooplankton, which comprises Cyanidiophyceae algae. The zooplankton feed composition according to claim 1, wherein the hot spring red algae is an alga belonging to the genus Galdieria. A method for producing zooplankton, comprising: feeding the zooplankton with the zooplankton feed composition of claim 1 or 2. A zooplankton that is proliferated by feeding the zooplankton feed composition of claim 1 or 2. A method for producing aquatic organisms, comprising: feeding aquatic organisms with zooplankton produced by the method for producing zooplankton of claim 3. A water additive for aquaculture of aquatic organisms, which comprises hot spring red algae. The water additive for aquatic organisms as claimed in claim 6, wherein the above-mentioned hot spring red algae are unicellular red algae.

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