Aquaculture method

Abstract

This aquaculture method includes: a salt-feeding step for imparting sodium-chloride-containing salt feed to cultured fish; a feeding stopping step for stopping feeding to cultured fish to which the salt feed is imparted in the salt-feeding step for at least 6 hours and less than 48 hours; and a killing step for killing cultured fish for which feeding is stopped in the feeding stopping step.

Description

Cultivation method

[0001] The present invention relates to a farming method for obtaining farmed fish with enhanced flavor.

[0002] In recent years, various methods for improving the flavor of farmed fish by improving the umami of fish meat have been studied. It is known that the umami, sweetness, bitterness, etc. of fish meat are influenced by the amino acid components in the fish meat. For example, a method for improving the umami of fish meat is known in which fish are fed a fish feed containing one or both of D-alanine and DL-alanine, with the aim of improving the umami of the edible parts of the fish (see, for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2005-218339

[0004] However, since feeding amino acids to farmed fish does not necessarily mean that they are efficiently absorbed into the muscles, simply feeding farmed fish feed containing amino acids to enhance flavor requires a certain period of time to sufficiently improve the amino acid content of the fish meat. Furthermore, during this period, it is necessary to continue feeding the fish special feed containing amino acids different from regular feed, which is cost-inefficient. Furthermore, long-term flavor enhancement varies greatly between individual fish depending on the size of the fish in the fish tank, making it difficult to determine the timing of shipment.

[0005] In order to solve the above-mentioned problems, the present invention aims to provide an aquaculture method that can easily improve the flavor of fish meat in a short period of time.

[0006] The present inventors conducted extensive research to solve the above-mentioned problems, and as a result, they discovered that the above-mentioned problems can be solved by feeding farmed fish a specific diet and killing them after a predetermined period of time, focusing on the fact that fish can accumulate amino acids in their muscles by utilizing the mechanism of osmoregulation, and thus completed the present invention.

[0007] <1> A farming method comprising: a salting step of feeding farmed fish with a salt bait containing sodium chloride; a feed stopping step of suspending feeding of the farmed fish fed in the salting step for at least 6 hours but less than 48 hours; and a slaughtering step of slaughtering the farmed fish whose feeding has been stopped in the feed stopping step. <2> The farming method according to <1>, wherein the feed stopping step suspends feeding of the farmed fish for at least 6 hours but less than 30 hours. <3> The farming method according to <1> or <2>, wherein the sodium chloride content of the salt bait is 20 mass% or less of the total amount of the bait. <4> The farming method according to any of <1> to <3>, wherein the salt bait contains rock salt. <5> The farming method according to any of <1> to <4>, wherein the farmed fish are at least one species selected from red sea bream, yellowtail, tuna, striped jack, rainbow trout, and tiger pufferfish.

[0008] According to the present invention, it is possible to provide a farming method that can easily improve the flavor of fish meat in a short period of time.

[0009] 1 is a graph showing the results of improving the flavor of an example.

[0010] <<Cultivation Method>> The aquaculture method of this embodiment includes a salting step in which cultured fish are fed a salted feed containing sodium chloride; a feed stopping step in which feeding of the cultured fish fed in the salting step is stopped for at least 6 hours but less than 48 hours; and a slaughtering step in which the cultured fish whose feeding has been stopped in the feed stopping step is slaughtered. This aquaculture method of this embodiment can increase the amount of free amino acids in the cells of the cultured fish (hereinafter sometimes referred to as "intracellular amino acid content"), thereby enhancing the overall flavor of the edible portion (so-called "seasoning"). Therefore, cultured fish obtained by this aquaculture method have a deliciousness not found in fish (farmed fish or wild fish) that are not cultured by this embodiment. Seasoning is achieved primarily by artificially increasing the amount of amino acids in the muscle and is different from aging (which primarily increases inosinic acid by aging fish meat). Therefore, further aging after seasoning is expected to further enhance the synergistic effects of aging in the cultured fish after seasoning.

[0011] There is no particular reason why the aquaculture method of this embodiment can improve the flavor of farmed fish, but one possible reason is that feeding salty food increases the blood osmotic pressure of the farmed fish, which in turn increases the amount of amino acids present in the cells of the farmed fish, and furthermore, the farmed fish can be shipped with their intracellular amino acid levels at their peak.

[0012] Furthermore, according to the aquaculture method of this embodiment, the flavor of the cultured fish is enhanced using salt feed, allowing for a simple and low-cost method of enhancing the flavor of the cultured fish. For example, the aquaculture method of this embodiment allows the use of existing offshore fish pens as they are, eliminating the need to transfer the fish to a separate tank with an increased salt concentration in the water to enhance flavor. This eliminates the need for, for example, the labor and expense of constructing a new tank or the labor and expense of moving the cultured fish between the pen and the tank. Furthermore, it prevents stress and damage to the cultured fish that would otherwise be caused by moving them between the pen and the tank. Furthermore, the aquaculture method of this embodiment can increase the amount of amino acids present in the cells of the cultured fish in a short period of time, making it advantageous in terms of time and cost compared to methods that directly feed the fish continuously with feed containing amino acids, etc.

[0013] In this specification, "farmed fish" refers to fish that are raised in a fish preserve or the like before shipping, regardless of the length of time, and are the subject of the farming method of this embodiment, i.e., fish that are fed salted food in a salting step, and includes wild seedlings and artificially hatched farmed fish. Furthermore, even wild fish caught at sea (including "livestock farming") are included in the concept of "farmed fish" in this embodiment, as long as they are fed salted food in the salting step of this embodiment.

[0014] Each step of the aquaculture method of this embodiment will be described below.

[0015] <Salted Feeding Step> The salted feeding step is a step of feeding farmed fish with salted feed containing sodium chloride. According to the farming method of this embodiment, by feeding farmed fish with salted feed, the amount of amino acids present in the cells of the farmed fish can be increased easily and in a short period of time, and the edible parts can be improved in flavor. Here, "edible parts" refers to parts that are normally eaten by humans, but is not particularly limited thereto, and mainly includes muscle tissue and internal organs other than bones.

[0016] The amount of sodium chloride in the salt feed can be changed as appropriate taking into consideration the type and size of the farmed fish, and can be set, for example, so that the salt concentration in the blood of the farmed fish is, for example, 0.95 to 1.20%. Specifically, the amount of sodium chloride in the salt feed is not particularly limited, but from the viewpoint of the feeding ability of the farmed fish (hereinafter sometimes referred to as "feeding ability"), it is preferably 20% by mass or less of the total amount of the feed, and from the viewpoint of the balance between the increase in intracellular amino acid content and the feeding ability of the farmed fish, it is preferably 2 to 15% by mass, and more preferably 3 to 10% by mass.

[0017] The form of sodium chloride in the salt bait is not particularly limited, but for example, rock salt is preferred from the viewpoint of improving the feedability of farmed fish by making it difficult for the sodium chloride to dissolve instantly when it comes into contact with water, and granular rock salt is even more preferred from the viewpoint of reducing exposure of the sodium chloride from the surface of the salt bait and improving the feedability of farmed fish, with approximately 2 to 8 grains of rock salt per 1 g being even more preferred.

[0018] In addition to sodium chloride, potassium chloride can be used in the salt bait, which can improve the amount of sodium chloride absorbed by the farmed fish. The amount of potassium chloride in the salt bait can be appropriately changed taking into account the type and size of the farmed fish, but from the perspective of the absorption mechanism of inorganic salts in the intestine, it is preferably 0.2 to 2.0 mass %, more preferably 0.5 to 1.0 mass %, of the total amount of the entire feed.

[0019] From the viewpoint of feeding ability of the farmed fish, the salted bait preferably contains water. The water content in the salted bait can be appropriately changed taking into consideration the type and size of the farmed fish, etc., but is preferably 5 to 20% by mass, more preferably 8 to 12% by mass, of the total amount of the bait.

[0020] As other components in the salted bait, for example, components contained in general fish bait depending on the type of farmed fish can be appropriately used, such as fish meal, etc. For example, when the salted bait contains fish meal, the content of fish meal in the salted bait is preferably 0 to 60% by mass, more preferably 0 to 40% by mass, of the total amount of the entire bait, from the viewpoint of suppressing the odor of the farmed fish after feeding is stopped.

[0021] The shape, size, and mass of each salt bait are not particularly limited, and can be appropriately changed to a spherical, cylindrical, rectangular, or other shape, taking into account the type and size of the farmed fish, etc. The mass of each salt bait is preferably 0.1 to 3.0 g, more preferably 0.2 to 2.6 g, from the viewpoint of feeding ability of the farmed fish.

[0022] The amount of feed per farmed fish in the salt feeding step is not particularly limited and can be changed as appropriate taking into consideration the type and size of the farmed fish, etc. However, from the viewpoint of the feeding ability of the farmed fish, it is preferable that the salt content in the feed be 10 to 50 g, and more preferably 20 to 30 g, based on the body weight (1 kg) of the farmed fish.

[0023] <Feeding Cessation Step> The feeding cessation step is a step in which feeding of cultured fish fed salty feed in the salty feed step is stopped for 6 hours or more but less than 48 hours. Hereinafter, the period during which feeding is stopped may be referred to as the "feeding cessation period." The amount of intracellular amino acids increases with the increase in blood pressure osmotic pressure caused by feeding salty feed, reaches a peak value after a predetermined period, and then gradually decreases over time. In the aquaculture method of this embodiment, the feeding cessation period is less than 6 hours or 48 hours, so the effect of increasing intracellular amino acids obtained by feeding salty feed can be fully exerted, and the cultured fish can be shipped with intracellular amino acid amounts near their peak.

[0024] The feeding stop period in the feeding stop step is preferably 6 hours or more and 30 hours or less, more preferably 6 hours or more and 24 hours or less, from the viewpoint of further fully exerting the flavor-improving effect.

[0025] <Slaughtering process> The slaughtering process is a process of slaughtering the farmed fish whose feeding has been stopped in the feed stopping process. In the farming method of this embodiment, by slaughtering the farmed fish promptly after a specific feed stopping period has elapsed, the farmed fish can be shipped with the amount of amino acids in the muscle cells in the edible part at its peak. In the slaughtering process, it is preferable to slaughter the farmed fish promptly after the feed stopping period has elapsed without feeding them again.

[0026] (Amino Acids) When cultured fish are fed salty food as described above, the total intracellular amino acids increase over time. Examples of amino acids that increase in the cells of cultured fish (e.g., red sea bream) include aspartic acid, glutamic acid, etc., which are related to umami components; serine, glycine, threonine, proline, glutamine, asparagine, etc., which are related to sweet components; and histidine, arginine, tyrosine, etc., which are related to bitter components.

[0027] There are no particular limitations on the means for killing farmed fish, and any known method can be used depending on the type of farmed fish. Examples of such methods include ice killing, live killing, nerve killing, etc. After killing, farmed fish can be subjected to treatments such as bleeding, if necessary.

[0028] <Other Steps> The aquaculture method of this embodiment is not particularly limited, but a normal aquaculture method is carried out depending on the type of farmed fish, etc., and a salt feeding step is carried out before the feeding stopping step before shipping. Note that the aquaculture method of this embodiment may also include a step of stopping normal feeding before the salt feeding step in order to improve feeding preference for the salt feed.

[0029] In one example of the above-mentioned typical aquaculture method, farmed fish are transferred to dedicated cages or tanks and managed under breeding management conditions, adjusting the feeding, water temperature, fish density, etc. For example, the number of times and amount of feeding per day to farmed fish before the salting step in this embodiment is not particularly limited and can be set appropriately depending on the type of farmed fish, etc., but it is preferable to feed the farmed fish by scattering the food inside the cage at least once a day. The feed may be live fish feed or compound feed such as pellets, or feed prepared by crushing live feed and mixing it with compound feed for moist pellets. The ingredients of the compound feed are not particularly limited, but typically include animal feed, grains, vegetable oil cakes, oils and fats, various vitamins, minerals, etc.

[0030] In one example of the aquaculture method of this embodiment, the water temperature in the fish pens or tanks is not particularly limited and can be set appropriately depending on the type of farmed fish, etc. In the case of a tank, the water temperature can be adjusted by using a heater or the like, but in the case of a fish pen installed on the sea for, for example, red sea bream or yellowtail, the farmed fish can be managed under desired temperature conditions by appropriately selecting the installation location and region of the pen.

[0031] As an example of the aquaculture method of this embodiment, the rearing density of the farmed fish in the fish cages or tanks is not particularly limited and can be set appropriately depending on the type of farmed fish, etc. However, for example, in consideration of the work efficiency in the salt feeding process, the relationship between the weight of the farmed fish and the capacity of the fish cages, etc., is set to 1 to 6 kg / m. ３ is preferred, and 2 to 5 kg / m ３ The size of the fish preserve or tank is not particularly limited as long as it allows the farmed fish to swim without contacting each other, but for example, it can be about 5 to 10 m long x 5 to 10 m wide and 5 to 10 m deep.

[0032] As an example of the aquaculture method of this embodiment, the period of aquaculture up to the salt feeding step is not particularly limited, and can be determined appropriately depending on the aquaculture fish.

[0033] <Cultivated fish> The type of farmed fish that can be cultured using the farming method of this embodiment is not particularly limited, and may be any of saltwater fish, freshwater fish, and amphidromous fish. Examples of farmed fish that can be cultured using the farming method of this embodiment include fish belonging to the Sparidae family of the order Perciformes (e.g., red sea bream, yellow sea bream, black porgy, etc.), fish belonging to the Carangidae family of the order Perciformes (e.g., yellowtail, striped jack, horse mackerel, etc.), fish belonging to the Carangidae genus of the order Perciformes (e.g., yellowtail, amberjack, yellowtail, etc.), fish belonging to the Scombridae family of the order Perciformes (e.g., bluefin tuna, yellowfin tuna, bigeye tuna, etc.), fish belonging to the Salmonidae family of the order Salmoniformes (e.g., rainbow trout, etc.), and fish belonging to the Tetraodontiformes family of the genus Pufferfish (e.g., tiger pufferfish, etc.). Preferred examples of the target of the farming method of this embodiment include at least one species selected from red sea bream, yellowtail, tuna, striped jack, rainbow trout, and tiger pufferfish.

[0034] Although one aspect of this embodiment has been described above, the present invention is not limited to the above description.

[0035] The present invention will be specifically described below using examples, but the present invention is not limited to the following examples.

[0036] Example 1 [Seasoning test] 5,000 red sea bream (approximately 1,000 g per fish) were released into a fish pen measuring 10 m x 10 m x 10 m in length, width, and depth, and fed once a day for 730 days. The fish were then stopped feeding for two days without feeding. After the feeding was stopped, the fish were fed a salt pellet bait (0.2 g per pellet) with the following composition at a feeding rate of 15 g per fish (salt feeding step). After feeding with the salt pellet, the fish were not fed any other bait for one day (24 hours) (feeding stopping step). After one day had passed, the red sea bream were captured and killed (killing step).

[0037] (Composition of salt bait) Sodium chloride 5% by mass (5.7% by mass when the amount of sodium chloride in the EP sample below is taken into account) Potassium chloride 1% by mass Moisture 11% by mass Remaining amount of commercially available EP sample (Product name: Himezakura, manufactured by Higashimaru Co., Ltd.; ingredients (crude protein 46.0% or more (main ingredient: fish meal), crude fat 10.0% or more (main ingredient) shrimp meal, crude fiber 2.5% or less (main ingredient: krill meal), crude ash 15.0% or less, calcium 2.0% or more, phosphorus 1.0% or more, animal-derived ingredients 60%)

[0038] The amount of free amino acids (intracellular amino acids) (mg / 100g) in 100g of fish meat was measured for two red sea bream (approximately 1000g / fish) before being fed a salted bait (before the salting step) and two red sea bream that had undergone the aquaculture method of this embodiment (salting step, feeding stop step, and killing step) by simultaneous analysis using a high-performance liquid chromatograph triple quadrupole mass spectrometer (product name: High-Performance Liquid Chromatograph Mass Spectrometer LCMS-8060, manufactured by Shimadzu Corporation). The average value of the free amino acid concentration in the fish meat of the red sea bream killed before being fed a salted bait is designated "control" in the figure, and the average value of the free amino acid concentration in the fish meat of the red sea bream that had undergone the aquaculture method of this embodiment is designated "5% salted bait." The results are shown in Figures 1 and 2.

[0039] As shown in Figures 1 and 2, it was confirmed that the red sea bream cultivated by the method of this embodiment had a significantly increased total amino acid concentration, including umami components (aspartic acid, glutamic acid), sweet components (serine, glycine, threonine, proline, glutamine, asparagine), and bitter components (histidine, arginine, tyrosine), compared to the control.

[0040] Example 2: Salt Concentration of Salted Bait [Seasoning Test] Twenty test fish (red sea bream) weighing an average of 800 g were housed in a 5-ton oval test tank (longer diameter 320 cm, shorter diameter 100 cm, depth 115 cm) and fed with a regular feed (Himezakura EP Feed, manufactured by Higashimaru Co., Ltd.) once a day until satiation. After feeding, the fish were fasted for two days. Then, the fish were fed the following salted feed in a satiation amount (satiation feeding). Satiation feeding was defined as when it was confirmed that no feed was expelled from the fish 5 to 15 minutes after feeding, and the fish had ingested a satiation amount of the salted feed. The amount of salted feed consumed was generally approximately 0.8 to 1% of body weight. After feeding with the salted feed, the fish were not fed any other feed for one day. After one day had passed, the red sea bream were captured and killed by live killing.

[0041] (Fish feed (salt bait) composition) Sodium chloride crystals 0-20% by mass (see Table 1 below for salt concentration) Potassium chloride 1% by mass Moisture 11% by mass Remaining amount of commercially available EP sample (product name: Himezakura, manufactured by Higashimaru Co., Ltd.; ingredients (crude protein 46.0% or more (main ingredient: fish meal), crude fat 10.0% or more (main ingredient) shrimp meal, crude fiber 2.5% or less (main ingredient: krill meal), crude ash 15.0% or less, calcium 2.0% or more, phosphorus 1.0% or more, animal-derived ingredients 60%)

[0042] [Evaluation of palatability] The salty baits shown in Table 1 below were given to the fish, and the amount of salty bait remaining in the tank was counted after 15 minutes. The fish were then comprehensively evaluated according to the following criteria to see if they showed interest in the bait and bit into it, and if they regurgitated it after biting.

[0043] (Criteria) A: Less than 3 grains of salted food remained in the tank. B: 3 or more grains but less than 10 grains of salted food remained in the tank. C: 10 or more grains but less than 15 grains of salted food remained in the tank. D: 15 or more grains of salted food remained in the tank.

[0044] [Measurement of free amino acid content in fish meat] Fish meat was fed different fish feeds (salt feeds) with salinity concentrations ranging from 0 to 20% by mass. Five red sea bream in each test group were simultaneously analyzed for free amino acid (intracellular amino acid) content (mg / 100g) in 100g of fish meat using a high-performance liquid chromatograph triple quadrupole mass spectrometer (product name: High-Performance Liquid Chromatograph Mass Spectrometer LCMS-8060, manufactured by Shimadzu Corporation). The average total amino acid concentration, including umami components (aspartic acid, glutamic acid), sweet components (serine, glycine, threonine, proline, glutamine, asparagine), and bitter components (histidine, arginine, tyrosine), was calculated for each example and comparative example, and the degree of increase compared to before feeding the salt feed was evaluated according to the following criteria: (Criterion) A: The average total amino acid concentration increased by 1.3-fold or more compared to the control (criteria). B: The average total amino acid concentration increased by 1.2 to less than 1.3 times compared to the control (standard). C: The average total amino acid concentration increased by less than 1.2 times compared to the control (standard).

[0045]

[0046] As shown in Table 1, the red sea bream fed the salted feed of the Example had an increased total amino acid content compared to the control (standard), indicating an improved flavor. Furthermore, as shown in Table 1, the red sea bream fed the fish feed of the Example, a feed with a salt concentration of 2.5 to 10% by mass, had a high feed intake and a high preference for the salted feed. Furthermore, because red sea bream are sensitive to the salty taste of salted feed with a salt concentration of 15% or more, feed intake was relatively low and the phenomenon of spitting out the feed was also observed. Furthermore, the total amino acid concentration in the fish meat of red sea bream fed a salted feed with a salt concentration of 2.5 to 10% by mass increased significantly. Meanwhile, it was confirmed that the amount of free amino acids in the fish meat of fish fed a salted feed with a salt concentration of 15% or more was lower than that of red sea bream fed a salted feed with a salt concentration of 2.5 to 10% by mass.

[0047] Example 3: Feeding Stopping Period After Feeding Salt Food [Taste Enhancement Test] Twenty-five test fish (red sea bream) weighing an average of 800 g were housed in a 5-ton oval test tank (longer diameter 320 cm, shorter diameter 100 cm, depth 115 cm) and fed with a regular feed (Himezakura EP Feed, manufactured by Higashimaru Co., Ltd.) once a day until satiation. After feeding, the fish were fasted for two days. Then, a satiating amount of salt food with a 10% salt concentration was fed (satiating feeding). Satiating feeding was defined as the fish having ingested a satiating amount of salt food when it was confirmed that no food had been expelled from the fish 5 to 15 minutes after feeding. The amount of salt food consumed was generally approximately 0.8 to 1% of body weight. Five red sea bream were caught and killed 6, 24, 30, and 48 hours after feeding the salted feed. Five fish were killed and their flesh was collected and frozen at -20°C. The frozen red sea bream flesh was subjected to measurement of the free amino acid content, and the time at which the free amino acid content of the flesh increased was comprehensively evaluated using the method described below. Furthermore, because the lipids and fish meal contained in the feed give the fish meat an unpleasant odor, the stomach and intestines were visually inspected for residues of the feed when the flesh was collected using the method described below.

[0048] (Composition of fish feed of this embodiment) Sodium chloride crystals 10% by mass Potassium chloride 1% by mass Water 11% by mass Remaining amount of commercially available EP sample (product name: Himezakura, manufactured by Higashimaru Co., Ltd.; ingredients (crude protein 46.0% or more (main ingredient: fish meal), crude fat 10.0% or more (main ingredient) shrimp meal, crude fiber 2.5% or less (main ingredient: krill meal), crude ash 15.0% or less, calcium 2.0% or more, phosphorus 1.0% or more, animal-derived ingredients 60%)

[0049] (Measurement of free amino acid content in fish meat) The amount of free amino acids (intracellular amino acids) (mg / 100g) in 100g of fish meat was measured for five red sea bream before (0 hour) feeding the fish feed (salt feed) of this embodiment and after (6, 24, 30, and 48 hours) feeding the salt feed. The amount of free amino acids (intracellular amino acids) in 100g of fish meat (mg / 100g) was measured by simultaneous analysis using a high-performance liquid chromatograph triple quadrupole mass spectrometer (product name: High-Performance Liquid Chromatograph Mass Spectrometer LCMS-8060, manufactured by Shimadzu Corporation). The average total amino acid concentration, including umami components (aspartic acid, glutamic acid), sweet components (serine, glycine, threonine, proline, glutamine, asparagine), and bitter components (histidine, arginine, tyrosine) for each example and comparative example, was calculated, and the degree of increase compared to before feeding the salt feed was evaluated according to the following criteria. (Criteria) A: The average total amino acid concentration increased by 1.3 times or more compared to before feeding the salt feed. B: The average total amino acid concentration increased by 1.2 to less than 1.3 times compared to before feeding the salty diet. C: The average total amino acid concentration increased by less than 1.2 times compared to before feeding the salty diet.

[0050] (Feed residues in the stomach and intestines of red sea bream) When collecting red sea bream meat, the abdomen was opened and the feed residues in the stomach and intestines were visually checked and evaluated according to the following criteria. (Criteria) A: No feed residues were found in the stomach and intestines. B: A small amount of feed residues was found in the stomach and intestines.

[0051]

[0052] The results in Table 2 show that the feeding stop period in the feeding stop step is preferably 6 to 30 hours, more preferably 6 to 24 hours, from the viewpoint of fully exerting the flavor-improving effect. Furthermore, when the flavor-improving effect and the influence of remaining food are taken into consideration, it is found that a period of 12 to 30 hours is particularly preferable.

[0053] The disclosure of Japanese Patent Application No. 2023-219710, filed on December 26, 2023, is incorporated herein by reference in its entirety. In addition, all documents, patent applications, and technical standards mentioned in the specification are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard was specifically and individually indicated to be incorporated by reference.

Claims

1. A culturing method comprising: a salt bait step of feeding cultured fish with a salt bait containing sodium chloride; a feeding stop step of stopping feeding the cultured fish fed with the salt bait in the salt bait step for 6 hours or more and less than 48 hours; and a squeezing step of squeezing the cultured fish whose feeding has been stopped in the feeding stop step.

2. The culturing method according to claim 1, wherein the feeding stop step stops feeding the cultured fish for 6 hours or more and 30 hours or less.

3. The culturing method according to claim 1, wherein the content of sodium chloride in the salt bait is 20% by mass or less based on the total amount of the whole bait.

4. The culturing method according to claim 1, wherein the salt bait contains rock salt.

5. The culturing method according to claim 1, wherein the cultured fish is at least one selected from red sea bream, yellowtail, tuna, striped jack, rainbow trout, and tiger puffer.

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