JPH07303432A - Fish culture method - Google Patents

Abstract

PURPOSE:To carry out fish culture by controlling the food consumption of culture fish by controlling the carbon dioxide gas concentration in the culture water, keep high water-quality, improve the insufficient feed intake of the fish and stably produce cultured fish. CONSTITUTION:The food consumption of culture fish is controlled by controlling the carbon dioxide gas concentration in the culture water to perform the culture of fish such as eel. The control of carbon dioxide gas is performed by increasing the carbon dioxide gas concentration with sodium bicarbonate, etc., or by controlling hydrogen ion concentration. Preferably, the carbon dioxide gas concentration and the hydrogen ion concentration in the culture water are used as indices for the control and maintenance of the feeding behavior of the fish and the activity of the coexisting organism in the culture water.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides fish culture with good water quality by adjusting and maintaining the carbon dioxide concentration and hydrogen ion concentration in the fish culture water, which enables continuous feeding. Regarding the method.

[0002]

2. Description of the Related Art Conventionally, as means for improving water quality of fish farming, those harmful to fish such as ammonia, nitrite, amine,
Sulfides are treated by physicochemical adsorption and substitution reactions using activated carbon and materials with high ion exchange capacity (such as zeolite and ion exchange resins), and treatment of nitrifying bacteria, sulfur bacteria, photosynthetic microorganisms, etc. There is provided a technique for converting into harmless one by chemical oxidation.

[0003]

[Problems to be Solved by the Invention] However, it is sometimes plagued by extreme water quality change (water change) due to poor feeding of unknown cause, which is considered to be other than diseases and parasites, and large breeding of plankton such as rotifer and water-bloom. At present, it is not always possible to create good water quality (water production) for fish farming. Especially in aquaculture farms that are closed water areas, when faced with such problems during initial water production and during times of severe climate change, people often eat poorly or raise their noses. According to tradition, formalin, potassium permanganate, fertilizer, pesticides, etc.
The current situation is that there is no suitable and effective solution, and it has not yet been fully elucidated academically at the field level.

An object of the present invention is to provide a fish-cultivating method, that is, a stable method for producing fish by pursuing the above-mentioned causal relationship of poor feeding in fish-culturing and finding a solution to the problem.

[0005]

Means for Solving the Problems As described above, the present inventor has conducted diligent research on the causal relationship between poor feeding in fish farming and the difference in the overall aquatic environment and structure of the quality of feeding. It was found that the carbon dioxide concentration greatly acts as an important factor for improving the food intake in fish farming, and the inventors invented a fish farming method for controlling the food intake of this fish farm by the carbon dioxide gas concentration in the fish farm water.

Since the carbon dioxide concentration in fish culture water is related to the pH in fish culture water, the concentration of dissolved carbon dioxide gas and p
It has been found that by maintaining H within a certain range, it is possible to provide good quality of water to fish farms and feed them continuously, and completed the present invention.

Regarding carbon dioxide, generally, in greenhouse cultivation of agricultural products, the concentration of carbon dioxide in the air is increased to enhance the photosynthetic activity of plants, or the concentration of carbon dioxide in water is increased to increase the concentration of carbon dioxide in water for appreciation and chlorella spirulina. Although it is known that the photosynthetic activity of photosynthetic microorganisms is increased to improve productivity and quality, and that the enzyme activity of photosynthetic bacteria (Rhodopseudomonas sp.) Is increased, carbonic acid is added to fish. No technology was known to be effectively used for the production of Furthermore, the water quality standards for water production of fish farms are generally pH, dissolved oxygen, ammonia, nitrous acid, nitric acid, etc., but there is no standard for carbonic acid substances, but rather a large amount of carbonic acid for fish and animals. Gas is harmful because it interferes with the respiratory system. For example, in eels, 20
It is said that harmful levels are reached at mg / liter or higher, and it has been conventionally treated as unilaterally harmful.

[0008] However, when the fish culture water which was fed well for a long period of time was examined, the carbon dioxide concentration (carbonate concentration) and pH in the fish culture water were within a certain range, and structurally, in house culture, It has a sealed structure that allows carbon dioxide to accumulate in the air at a high concentration, and has an aerobic structure with water permeability that allows organic substances such as residues and feces to be efficiently decomposed into carbon dioxide. Many ponds keep the illuminance low to reduce the carbon dioxide assimilation activity. Furthermore, the pH of the raw water used in a fish pond with good feeding tends to be low and the concentration of dissolved carbon dioxide tends to be high. On the other hand, when the concentration of dissolved carbon dioxide is low, the freezing density is increased to increase the concentration of dissolved carbon dioxide. When it was raised, water was formed more quickly, and it tended to be eaten better. Also, in eels, the higher the freeing density, the better the water production and the higher the dissolved carbon dioxide concentration.

On the other hand, when investigating poorly fed fish-cultured water, one or both of the dissolved carbon dioxide concentration and the pH are outside a certain range, and most of them have a dissolved carbon dioxide concentration below that. It was the opposite of. However, due to aerobic decomposable carbon dioxide of organic matter, or carbonic acid, or carbon dioxide and acid / alkali by the aforementioned structural carbonic acid increasing method,
By changing and maintaining the dissolved carbon dioxide concentration and pH level that are good for feeding, the feeding condition will be extremely good, and regardless of whether the water is closed or open, it is easy to “make water” without relying on the professional intuition of the site. We found that we could do this and completed this method of fish raising.

The present invention is a fish-cultivating method characterized in that the amount of fish-eating consumed is controlled by the concentration of carbon dioxide in the fish-culturing water.
In addition, it is a fish-cultivating method of increasing the carbon dioxide concentration in the fish-culture water in order to increase the amount of fish-eating.

Various carbon dioxide gas sources can be used to increase the carbon dioxide concentration in the fish culture water, but it is important to control and maintain the carbon dioxide gas source depending on the hydrogen ion concentration in the fish culture water.

When the carbon dioxide concentration in fish culture water is controlled and maintained by the carbonic acid substance, the carbon dioxide gas source is not limited to a special one. Carbon dioxide, such as sodium bicarbonate, sodium carbonate, potassium bicarbonate, calcium bicarbonate, ammonium bicarbonate, which is generated by lowering the pH of the carbonate solution, or a gas or liquid containing high-concentration carbon dioxide and carbon dioxide. You may use itself. Further, carbon dioxide gas generated by chemical oxidation (combustion) of an organic substance may be used, as long as it is not harmful to fish farming, and may be at a level not harmful. “Organic matter” here means
Organic compounds in a broad sense, including not only special ones but also foods and feeds, wastes thereof, manure, plants and residues thereof, and simple substances of various organic substances such as alcohol, formalin, organic acids and hydrocarbons. Refers to.

The "pH lowering" source (acidic substance) referred to herein is not limited to a special one such as hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, phosphoric acid compound, various organic acids, carbonic acid, etc. Refers to "acid".

The term "carbonic acid substance" as used herein means carbon dioxide gas (CO
₂ ), carbonic acid (H ₂ CO ₃ ), bicarbonate ion (HC
O ₃ ⁻ ) and a carbonate ion (CO ₃ ²⁻ ) are collectively referred to. The reason for increasing the dissolved carbon dioxide concentration by sodium bicarbonate and the behavior of various carbonates depending on pH will be described below.

An aqueous solution of sodium bicarbonate NaHCO ₃ is hydrolyzed as shown below to show weak alkalinity, and has a pH of 8.4 at 0.1 mol / liter. Sodium bicarbonate is

[Chemical 1] And dissociate bicarbonate ions (HCO ₃
^- ) Is further ionized, and a small amount of H ⁺ and carbonate ion (CO
₃ ^2- ) but mostly reacts with water,

[Chemical 2] Since it produces OH ⁻ , it exhibits weak alkalinity. Therefore, there is almost no dissolved carbon dioxide gas on the alkaline side. Carbonate is carbon dioxide (CO ₂ ), carbonic acid (H ₂ C
O _3), bicarbonate ions (HCO ₃ ^-), carbonate ions (C
O ₃ ^2- ) exists in 4 states, but the ratio is pH
When the relationship between the four parties changes, the pH changes, and when the pH changes, the relationship between the four parties also changes. The relationship between the existence ratio and pH in the case of pure water at 25 ° C. will be described below.

CO ₂ dissolved in water has a pH value of 7 or less.
A reaction of hydrating to H ₂ CO ₃ and a reaction of producing HCO ₃ ⁻ (bicarbonate ion) are considered.

[0017]

[Chemical 3]

[Chemical 4]

Further, when the pH is 7 or more, a reaction with OH ⁻ begins to occur, and the ratio becomes larger as it becomes more alkaline.

[0019]

[Chemical 5]

[0020] H ₂ CO ₃ dissociates HCO ₃ ^-, CO ₃
^2- to form.

[0021]

[Chemical 6]

[Chemical 7]

The parallel of (a) is inclined to the left, and the dissociation constant K _H is H ₂ CO concentration of 1

## EQU1 ## K _H = [H ₂ CO ₃ ] / [CO ₂ ] [H ₂ O] = 2.58 × 10 ^-3 (f), and the carbon dioxide gas dissolved in water when the pH is low is Mostly C
O ₂ remains as it is, and H ₂ CO ₃ is 0.4% or less of CO ₂ .

Next, the dissociation constant K _A of (b) in which H ₂ CO ₃ dissociates is

[Number 2] ^{_{K A = [H +] [}} HCO 3 -] / [H 2 CO 3] = 2.5 × 10 -4 ...... given as (g), but the concentration of H ₂ CO ₃ is The first apparent dissociation constant K _a1 is used because it is actually low.

[0024]

Equation 3] ^{_{K a1 = [H +] [}} HCO 3 -] / [CO 2 + H
₂ CO ₃ ] = 4.3 × 10 ⁻⁷

K _A is a value obtained from K _a1 and K _H , and K _a1 also includes K _A.

The second dissociation constant K _a2 of (e) in which HCO ₃ ⁻ is further dissociated is

Equation 4] ^{_{K a2 = [H +] [}} CO 3 2-] / [HCO 3 -]
= 5.6 × 10 ⁻¹¹ (above, all values for pure water at 25 ° C.).

From the above, pK _a1 = 6.35 and K _a2 = 1
It becomes 0.32, and due to the change in pH, CO ₂ + H ₂ O →
The proportions of H ₂ CO ₃ , HCO ₃ ⁻ , and CO ₃ ²⁻ can be determined by using the Henderson Hasselbach number.

[0028]

Equation 5] _{pH = pK a1 + log {[} HCO 3 -] / [CO 2
+ H ₂ CO ₃ ]}

## EQU6 ## pH = pK _a2 + log {[CO ₃ ^2- ] / [H ₂ CO ₃ ]}

The calculation result is shown in FIG.
Below H5, most of it is in the form of CO ₂ , and around pH 8 is mostly in the form of HCO ₃ ⁻ , and CO ₃ ²⁻ is present at around pH 5 only at around 5%.

For the above reasons, it is possible to increase the dissolved carbon dioxide gas by lowering the pH to the acidic side, and by controlling the ratio of the carbonic acid substance and the acid, the optimum pH and dissolved carbon dioxide gas for various fish farms can be obtained. Concentration can be controlled simultaneously. In short, both the carbon dioxide concentration and the hydrogen ion concentration in the fish culture water can be adjusted and maintained to increase the food intake.

When the carbon dioxide concentration is controlled by the carbon dioxide itself, there are dissolution methods such as aeration of the carbon dioxide and increasing the carbon dioxide concentration in the fish farm. When carbon dioxide is dissolved in water,

[Chemical 8] As the carbon dioxide concentration rises, p
Since H is lowered, pH and dissolved carbon dioxide concentration can be controlled at the same time by adding an alkali or injecting water as needed. In the case of organic substances, if the organic substances are positively added to the fish culture water and the microorganisms respire or ferment the dissolved carbon dioxide concentration will rise, but the amount of organic substances, the amount of acid or alkali added, and the amount of water injection can be adjusted. Thus, the pH and the dissolved carbon dioxide gas concentration can be controlled at the same time. Once controlled, the water has a considerable buffering capacity, which reduces fluctuations in water quality. These controls require the measurement of pH and carbonates, but p
The H can be measured with an indicator or a pH electrode, and the carbonate substance can be measured by using a carbonate substance measuring electrode, the JIS (K0101) method, or a titration method.

The carbon dioxide concentration is not limited to the above-mentioned pH adjustment, addition of carbonic acid substances, etc., but the closed inside of the aquaculture house is controlled, the illuminance is adjusted, and the photosynthetic activity of photosynthetic organisms is controlled by physiologically active substances. It can also be controlled by.

The appropriate values of the carbon dioxide concentration and the hydrogen ion concentration in the fish culture water naturally vary depending on the type of the target fish, the growth process of the juvenile to the adult fish, and the condition setting of the aquatic environment such as closing or opening, and are uniform. Although it is not possible to determine the preferred range of each concentration, generally speaking, for dissolved fish such as loach, eel, and adult fish, which have a relatively low water level, the dissolved carbon dioxide concentration level is set to a high level. According to it, it is preferable to adjust the pH to about 5 to 7 to lower it to the acidic side, but for fish that live in clear stream waters such as sweetfish, Iwana, when compared to fish such as loach, eel and adult fish, it is dissolved It is not preferable to set the carbon dioxide concentration level too high.

On the other hand, from the viewpoint of the total aquatic environment of fish-cultured water, an increase in food intake according to the present invention leads to an increase in the amount of excreted ammonia, which may lead to ammonia poisoning and nitrite poisoning. It is recognized that increasing the concentration of carbon dioxide in the fish culture water promotes the nitrification activity of microorganisms such as nitrifying bacteria and denitrifying bacteria in the fish culture water, leading to the promotion of the nitrification rate of ammonia → nitrite → nitric acid. Therefore, by controlling the carbon dioxide concentration and hydrogen ion concentration in the fish culture water as indexes, the feeding behavior of the fish culture and the activity of the coexisting organisms in the fish culture water can be regulated and maintained.

[0035]

The present invention is based on the finding that the concentration of carbon dioxide in fish culture water largely acts as an important factor for improving the intake of fish in fish culture, and a fish culture method for adjusting the intake of fish culture with the concentration of carbon dioxide in fish culture water is provided. As the concentration of carbon dioxide gas in the fish culture water increases, poor feeding of fish can be improved, and the amount of fish consumed can be increased. In addition, by adjusting the carbon dioxide concentration and hydrogen ion concentration in the fish culture water, it leads to the stabilization of water quality and the stabilization of feeding, and it is also possible to control and maintain the feeding behavior of fish and the activity of coexisting organisms in the fish culture. it can.

[0036]

【Example】

(Example 1) A pond in a closed water area with an area of about 330 m ² , a water depth of about 1 m, and a total water volume of about 300 t was prepared in an eel culture house, and about 170 g / animal of 5 t eel was placed in the pond and cultured at 28 ° C. To prevent fluctuations in water quality due to photosynthetic microorganisms and a decrease in dissolved carbon dioxide concentration, the light-shielding rate was increased and the illuminance was set to 1 during the day.
It was less than 000 lux. In order to increase the dissolved carbon dioxide concentration, the carbon dioxide concentration in the air inside the eel house was set at 8000.
Carbon dioxide concentration in fish culture water is always 70-90 ppm
It was measured by a titration method so as to be mg / liter and adjusted by water injection. The pH was measured with an indicator and kept at 6.0-6.5 at all times. When it was lower than this, alkali (CaO) was added, and when it was higher, acid (calcium dihydrogen phosphate) was added to adjust the pH. It was The feed is a normal feed containing 75% fish meal and 23% starch as main components (the same applies in the following examples).

As a result, the amount of food intake (feeding amount) was 1% of the amount of eel input, which is said to be good for the farmer.
0 kg / day was maintained.

(Example 2) Similarly, in an eel feeding house, a pond in a closed water area with an area of about 330 m ² , a water depth of about 1 m, and a total water volume of about 300 t was prepared, and about 170 g / animal of 5 t was put in the pond. It was cultivated at a water temperature of 27 ° C. Use a filter tank to aerobically decompose sludge without replacing water to reduce the dissolved carbon dioxide concentration to 7
When keeping 0 mg / liter and pH around 6.4, the feeding condition became stable, and the feeding amount (feeding amount) was 1% of the eel input which is said to be good for the farmer. The average was about 50 kg / day.

(Example 3) 100 g of loach was bred in a water tank with a filtration tank containing 6.6 liters of water, and 1 g of a mixture of sodium bicarbonate and calcium dihydrogen phosphate was added thereto to adjust the pH to about 6. 8, dissolved carbon dioxide concentration of 70-90m
At g / l, loach became very well fed and the best water preparation for loach was easily completed.

Table 1 shows the relationship between changes in water quality and food intake.
It can be seen from Table 1 that before and after the addition of the mixture of sodium bicarbonate and calcium dihydrogen phosphate, the amount of food intake increased as the dissolved carbon dioxide concentration increased.

[0041]

[Table 1]

(Embodiment 4) An area of about 33 in an eel house.
A pond with a closed water area of 0 m ² , a depth of about 90 cm, and a total water amount of about 300 t was prepared, and about 170 g / animal of 5 t was placed in the pond and cultured at 27 ° C. The feeding amount was about 40 kg / day on average, but when the pH increased to around 7.0 due to changes in climate and the dissolved carbon dioxide concentration fell to 40 mg / liter or less, eating became poor. Therefore, 20 kg of a mixture of sodium bicarbonate and calcium dihydrogen phosphate was added, the pH was lowered to around 6.8, and the dissolved carbon dioxide concentration was 60%.
When the concentration was increased to mg / liter, the fed state recovered.

(Example 5) In a water tank with a filtration tank containing 34.5 liters of water, 345 g (average body weight 1.2 g) of loach was added to an eel feeding compound sample of 2.0% / body weight / day, and the average feeding amount was 20%. The animals were raised at a water temperature of 27.0 ° C. After acclimation for 4 days, pH 6.8 ± 0.2 and dissolved carbon dioxide concentration were adjusted to 30 by adding a mixture of sodium bicarbonate and calcium hydrogen diphosphate.
After increasing to mg / liter, changes in food intake and water quality, and behavior of loach were observed. No water exchange was performed during the test period.

Table 2 shows the results. E in Table 2
C is electric conductivity (μs), and DO is dissolved oxygen (ppm).

From Table 2, the nitrification activity increased from the second day,
It was found that increasing the concentration of carbon dioxide in fish culture water not only improves feeding conditions but also promotes the activity of nitrifying bacteria in fish culture water, leading to the promotion of nitrification rates such as ammonia → nitrite → nitric acid.

[0046]

[Table 2]

(Example 6) An area of about 50 in an eel house.
A pond (test zone) with a closed water area of 0 m ² , a water depth of about 70 cm, and a total water volume of about 350 t was prepared, and about 170 g / mouse of eel 5 t was placed in the pond and cultured at an average water temperature of 27 ° C. A mixture of sodium bicarbonate and calcium dihydrogen phosphate was added to the pond of this test area on the first day (1st day) of the start of eel cultivation.

FIG. 1 shows the intake of fish, the concentration of dissolved carbon dioxide (mg / liter), the concentration of ammonia nitrogen (mg / liter), and the concentration of nitrite nitrogen (m) in the pond of the test section.
g / liter), nitrate nitrogen concentration (mg / liter),
It is a graph which shows each day change of hydrogen ion concentration pH.

For comparison, a blank control pond to which a mixture of sodium bicarbonate and calcium dihydrogen phosphate was not added was prepared, and the change with time was similarly observed. The result is shown in FIG.

From FIG. 1 and FIG. 2, it is recognized that the dissolved carbon dioxide concentration and pH and the food intake (feeding amount) show a generally good correlation in both the test group and the control group, It was confirmed that the food intake (feeding amount) was increased by adjusting the dissolved carbon dioxide concentration.

Particularly, in the pond of the test section of the present invention to which a mixture of sodium bicarbonate and calcium dihydrogen phosphate was added,
Dissolved carbon dioxide concentration is 22 mg / liter, pH is 6.5
From around the time, the amount of food intake (feeding amount) was significantly increased compared to the control group, and the eating condition was improved.

In the test area, the dissolved carbon dioxide concentration began to decrease around the 16th day from the start of eel feeding, and the food consumption (feeding amount) drastically decreased on the 22nd day from the start of eel feeding. . Therefore, when a mixture of sodium bicarbonate and calcium dihydrogen phosphate was added again in order to increase the amount of food intake, the amount of food intake (feeding amount) increased as the concentration of dissolved carbon dioxide increased, and the farmer is doing well. The average amount of eel, which is said to be 1%, was about 50 kg / day. On the other hand, in the control area, food consumption (feeding amount)
Was about 35 kg / day on average.

Incidentally, the food intake (feeding amount) in the control area
The addition of a mixture of sodium bicarbonate and calcium dihydrogen phosphate on day 25 to confirm the recovery of
As shown in FIG. 2, recovery of food intake (feeding amount) was observed.

The present invention is not limited to the above embodiment.

[0055]

INDUSTRIAL APPLICABILITY As described above, according to the present invention, based on the finding that the carbon dioxide concentration in fish culture water greatly acts as an important factor for improving the food intake in fish culture, the food intake of fish culture is adjusted by the carbon dioxide concentration in the fish culture water. Since the fish culture method is used, poor feeding of the fish can be ameliorated by adjusting the carbon dioxide concentration in the fish culture water, and the consumption of the fish can be increased.

Further, by controlling the carbon dioxide concentration and hydrogen ion concentration in the fish culture water, it leads to stabilization of water quality and stabilization of feeding, and regulates and maintains the feeding behavior of fish culture and the activity of coexisting organisms in the fish culture water. It is also a very useful technology for the fisheries industry including ornamental fish.

[Brief description of drawings]

FIG. 1 is a graph showing daily changes in food intake (feeding amount) and water quality in a test plot according to an example of the present invention.

FIG. 2 Food consumption (feeding amount) in a control section according to a comparative example
3 is a graph showing changes in water quality over time.

FIG. 3 is a diagram showing the relationship between the ratio of carbon dioxide in water and pH.

Claims (6)

[Claims] 1. A method for raising fish, comprising controlling the amount of fish fed by the concentration of carbon dioxide in the fish culture water. 2. The fish-cultivating method according to claim 1, wherein the carbon dioxide concentration in the fish-cultivating water is increased. 3. The fish-cultivating method according to claim 1, wherein the carbon dioxide concentration in the fish-cultivating water is adjusted and maintained by the hydrogen ion concentration. 4. The fish-cultivating method according to claim 1, 2 or 3, wherein the carbon dioxide concentration in the fish-cultivating water is controlled and maintained by a carbonic acid substance. 5. The fish-cultivating method according to claim 1, 2, 3 or 4, wherein both the carbon dioxide concentration and the hydrogen ion concentration in the fish-cultivating water are adjusted. 6. A fish-culturing method characterized by controlling and maintaining the feeding behavior of fish and the activity of coexisting organisms in fish-water by controlling the concentration of carbon dioxide and hydrogen ion in the fish-culture water as indicators.