Specified Skills
Educational Textbook for the Fishing Industry Skills Proficiency Test (Aquaculture)(Feed-Supplied Aquaculture)

Japan Fisheries Association(First Edition: February 2020)

Table of Contents

1. Sea Aquaculture for Fish in Japan···································································· 1
2. Natural and Artificial Seeds ············································································ 2
3. Feed ············································································································· 5
4. Breeding Environments ·················································································· 6
5. Yellowtail Aquaculture ··················································································· 7(1) Yellowtail and Greater Amberjack Spawning Seasons and Locations ················ 8(2) Yellowtail and Greater Amberjack Names ····················································· 9(3) Securing Aquaculture Seeds ········································································ 9(4) Feeding Methods ······················································································ 10(5) Aquaculture Environments ········································································ 12(6) Aquaculture Facilities and Density······························································ 12(7) Fish Diseases and Countermeasures···························································· 12(8) Shipping ·································································································· 13
6. Red Sea Bream Aquaculture ··········································································· 14(1) Securing Seeds for Aquaculture ·································································· 15(2) Aquaculture Methods after Starting Cultivation············································ 17(3) Aquaculture Environments ········································································ 17(4) Aquaculture Facilities and Density······························································ 17(5) Adjusting the Body Color of Red Sea Bream·················································· 18(6) Fish Diseases and Countermeasures···························································· 19(7) Shipping ·································································································· 20
7. Fish Parts and Measurement ·········································································· 21(1) Names of Fish Parts ·················································································· 21(2) Fish Measurement ···················································································· 22
8. Ikejime Killing Method ·················································································· 23

1. Sea Aquaculture for Fish in Japan
Within the sea aquaculture for fish conducted in Japan, yellowtail species (yellowtail,greater amberjack, and yellowtail amberjack) are produced in the largest quantities,
followed by red sea bream, coho salmon, bluefin tuna, striped horse mackerel, blowfish
species, and jack mackerel (Fig. 1). Although all of these fish can be found throughout
Japan's territorial waters, with the exception of flounder and coho salmon, aquaculture
production is concentrated in Western Japan and the sea to the west of it.

StripedhorsemackerelBlowfishFlounder(3,000 t)(2,000 t)
Jack

Bluefin tunamackerel(17,000 t)
Coho
salmonYellowtail(138,000 t)
Red

sea

bream

Figure 1: Japan's Sea Aquaculture Yield for Fish (2017)
Source: "Production Statistics for Fishing and Aquaculture in 2018,"
Ministry of Agriculture, Forestry and Fisheries-1-2. Natural and Artificial Seeds
Fish aquaculture begins with securing fry called "seeds." There are two methods of
securing these seeds. The first is catching fry in their natural habitat and using them as
seeds for aquaculture (Fig. 2). Seeds for yellowtail and greater amberjack aquaculture
are secured by this method, which is called "natural seed collection."

Activities conducted naturally
Cultivation

Parent fish
Fertilized
egg

Larval
fish

Catch

Fry

Fry
or
fingerling

Shipment

Young
fish
or
adult
fish

Figure 2: Natural seed collection aquaculture method

The second method involves artificially producing seed. First, fry that have first beentaken from natural environments are grown to larger sizes. After the fry are grown, theenvironment is adjusted such that the fry can become parent fish, and their maturation
is promoted by administering hormones related to sexual maturity. Eggs are collectedfrom these mature parent fish, fertilized with discharged semen, and hatched. Spawningis divided into cases in which mature parent fish are put into aquariums and naturally
spawn and cases in which hormones are administered to induce spawning, after which
spawning occurs. Furthermore, when spawning does not naturally occur in an aquarium,pressure may be applied to the stomach region to eject the eggs and sperm so that-2-

fertilization can be carried out artificially in some cases.
A fish that has hatched from a fertilized egg is called a larval fish, and these larvalfish are grown into a fry and used as seeds for aquaculture. Moreover, fry produced inthis way are also grown into parent fish. A method of creating a production cycle withartificially produced fish, without catching fry from their natural environment, isreferred to as "complete aquaculture." Red sea bream, flounder, and tiger puffer are
produced using this method.

Larva

Catching in natural
water

l fishNew fishaquaculture

Fry
Fertilized egg

Fry

Promotion of＋

growthFingerling＋Fingerling

Promotion ofsexualMature
Young

fish

fish

maturity
Shipment

Figure 3: Complete aquaculture method

In aquaculture using subdivided fish tanks, fry are contained in a separate fish tankon the sea surface. A square fish tank with a height and width of about 10 m, called a"subdivided fish tank," is used for this purpose (Fig. 4). Compared to a land fish tank, a
subdivided fish tank has the merits of enable large capacity production with lower
facility costs, and eliminated the electricity fees required for water replacement, since-3-this occurs naturally through the flow of the ocean. However, it has also the demerit ofbeing easily affected by typhoons and red tides. A net hangs down below the sea surfaceof the fish tank. The mesh of the net is replaced with larger mesh as the fish grow. Fishaquaculture in Japan is often conducted in shallow waters on coasts (waters), so the nets
are not very deep (4 to 8 m). Compared to red sea bream and striped horse mackerel,
which have comparatively small bodies, yellowtail and tuna are larger and swim more
actively, so larger fish tanks are used.

Figure 4: Subdivided fish tank-4-

3. Feed
Regardless of the type of fish, live feed is no longer used by itself. Instead, modern
aquaculture always uses mixed feed, e.g., moist pellets, dry pellets, or extruder pellets(Fig. 5). Generally, feed is either given twice per day in the morning and at night or once
per day at one of these times (feed may be given every other day when the fish growlarger), but the smaller the fish, the more times per day they are fed. The amount of feed
given also increases as the fish grow. The ingredients for mixed feed include fish meator fish powder, and there are also additives such as oils, vitamins, minerals, and binders,which are mixed in.

© National Seawater Pisciculture Association

Moist Pellets

Dry Pellets

Made from ingredients such as raw

Made from ingredients suchfeed, fish powder, and fish oil. The

as fish powder, flour, andmixture can also be adjusted bysoybean oil residue. Thechanging the proportions, and additives

nutrient content is balanced insuch as nutrients and vitamins can beaccordance with the type ofincluded as well. This type of mixed

fish and to avoid crumbling infeed is often formulated at thewater. Generally, dry pellets

aquaculture site.

are produced at a feed plantthen purchased and provided
at the aquaculture site.

Figure 5: Various mixed feeds-5-

Mad from ingredients such as
fish

powder,soybeanProcessing

flour,

oilandresidue.
athightemperatures and pressures
improves the digestion andabsorption of the ingredients.
Generally, feed produced at afeed plant then purchased andprovided at the aquaculturesite.

4. Breeding Environments
The quantity of fish to be put into one fish tank should not be thought of in terms ofthe number of fish, but in terms of the weight per m3. Generally speaking, this weightshould be 4 to 8 kg/m3. Thus, when the fish are small, many can be put into one fish tank,
but as they grow, the number must be reduced. When the number of fish for one fishtank is too high, it may diseases to spread or worsen the water quality.
In fish aquaculture, when fish die in the period from the start of cultivation to the timeof shipment, the main factor is disease. The causes of diseases are bacteria, parasites,
and viruses. In some cases, treatments and prevention methods are available, but there
are also diseases for which there are still no countermeasures. When fish become ill,
medicine may be administered for treatment. In this case, it is important to follow the
dosage and regimen specified by fisheries medicine, which is determined for each type offish and each disease. If there are no countermeasures available, the fish that have fallen
ill or died must be quickly removed from the fish tank, and measures must be taken toprevent other fish from becoming infected.
In addition, waters where aquaculture fish tanks are installed are generally waters
with calm sea surfaces. In such waters, red tides may occur during hot periods in thesummer. If red tide occurs, in many cases this causes the deaths of numerous fish intanks. Red tide occurs due to a certain type of phytoplankton occurring in large
quantities. This occurs due to an excess of substances that provide nutrients tophytoplankton being present in the water. When red tide occurs, large-scale dying off ofthe fish be prevented by relocating the fish tank or increasing the depth of the net.
After fish have been kept in a fish tank for 1 to 2 years, they grow to a size suitable forshipment. Currently, in Japan, fish that are not very big such as red sea bream and-6-

flounders are often transported to the sites of consumption while still alive, but large
fish such as yellowtail, greater amberjack, and bluefin tuna, are killed at the production
area, processed, vacuum packed before being transported to the sites of consumption.
The production method differs for each type of fish. Methods for each type of fish aredescribed below.

5. Yellowtail Aquaculture
Yellowtail are distributed along the northwest Pacific Ocean and mainly inhabit thearea around the Japanese archipelago. On the other hand, greater amberjack are
distributed in waters the world over, including the Pacific Ocean, the Atlantic Ocean,the Mediterranean Sea, and the Indian Ocean, and they mainly inhabit warm areas andthe tropics.
As shown in the photographs, yellowtail and greater amberjack have a similar
appearance and are extremely difficult to tell apart. The greatest differentiating
characteristic of the greater amberjack is that it has a pattern on its head resembling
the Chinese character "八." In fact, kanpachi, the Japanese name for this fish, is said tobe derived from this pattern.

Figure 5: Yellowtail (left) and greater amberjack (right)-7-

(1) Yellowtail and Greater Amberjack Spawning Seasons and Locations
Yellowtail begin spawning around December to January around the midpoint between
the Okinawa Islands and China in the East China Sea and in the waters contiguous with
the Kuroshio Current. Around March to April, the spawning location moves to thewestern seas of Kyushu, and after that, it moves northward along the coast of theJapanese archipelago.

South Korea

Japan

Jun.

Periods whenmojako canbe caught

May

Mar. to Apr.

Apr.
Feb. to Mar.

TaiwanFigure 6: Spawning locations of yellowtail and periods when mojako (yellowtail fry)
can be procured* Yellowtail larvae procurement must be carried out within the period determined by each region.
The specific spawning locations of greater amberjack are not clear, but it is thought thatareas with high water temperature such as the southern seas of China, the area aroundTaiwan, and the waters of the Ogasawara Islands in the Pacific Ocean are spawning
locations (Fig. 7). When the seawater temperature reaches 20°C or higher, spawning
begins.

-8-

East China Sea

Taiwan?
Philippine Sea

Figure 7: Greater amberjack spawning locations (presumed)(2) Yellowtail and Greater Amberjack Names
Yellowtail are known as shusseuo, meaning the fish are called by different names as
they grow. In Kanto (Eastern Japan), they are called wakashi, inada, warasa, and buriin the stages of their life cycle. in Kansai (Western Japan), the names used mojako,

shibasu, hamachi, mejiro, and then buri. In Kyushu, they are called mojako, wakanago,yazu, hamachi, and buri. In aquaculture, they are sometimes referred to as hamachi.
Similar to yellowtail, greater amberjack are also called by different names as they grow,and their names are mojako, neigo, kampachi, and akabara.
The fry of yellowtail and greater amberjack are called mojako. This name is acombination of jako, which means “fry," and mo, which is used because they form groups
next to drifting seaweed (nagaremo in Japanese) which flows from the coast and gathers
above the surface of the sea.

(3) Securing Seeds for Aquaculture
For greater amberjack and yellowtail, fry (mojako) gather near drifting seaweed which
floats on the surface of the sea. When beginning aquaculture for greater amberjack or-9-yellowtail, fry are first collected together with the drifting seaweed (Fig. 7). This is thenbrought onto a fishing vessel to a location near the aquaculture site and put into the fishtank, and then aquaculture commences.

なが

も

した

(1)①流れ藻の下にブリやカンパ
Often, fry of yellowtail or greater
な ぎょ

しゅうだん

せいそく

amberjacklive in集groups
under driftingチの稚魚が団で生息しておおseaweed.
いることが多いのです。

なが

も

み

ふね

(2)
When drifting seaweed is found, a ship
②流れ藻を見つけたら、船で
ちか

なが

も

あみ

approaches
and the drifting seaweed is
近づき、流れ藻ごと網ですくとい取ってしまいます。
scoopedup whole in a net.
Figure 7: Collecting yellowtail and greater amberjack fry(4) Feeding Methods
Immediately after they are put into the fish tank, the yellowtail and greater amberjack
fry are provided with feed frequently throughout the day. The feed used is a mince of
seafood species such as jack mackerel, mackerel, and seahorse (recently, mixed feed isalso increasingly used), but as the fry grow larger, the mince is reduced and increasing
amounts of mixed feed (artificial feed) are introduced as the fish grow accustomed to it.
After the fish have grown accustomed to artificial feed, moist pellets, which are mixed
and formed from minced fish meat, powdered feed, and nutrients, as well as dry pellets
and extruded pellets for grown fish, are used.

- 10 -

Feed is supplied 4 to 8 times per day until the fry reach 100 g in weight, and it issupplied more often the smaller the fish are. After they exceed 100 g in weight, they are
fed twice per day, in the morning and the evening.
The food supply ratio for yellowtail each day with respect to the weight of the fish
when using dry pellets is as shown in Table 1. For example, a fish weighing 100g would
receive 4.0 gram (or 4.0%) at 22°C. This indicates the total feed per day. This proportion
changes based on various conditions, such as the water temperature and the healthcondition of the fish. For greater amberjack, feed required is about 20% less than foryellowtail. If too much feed is given, feeding efficiency will suffer and the remaining feed
will also worsen the water quality and the substratum around the aquaculture fish tank.
Fish weight

Table 1: Examples of dry pellet feed ratios for yellowtail(Examples published by Marubeni Nisshin Feed Co., Ltd.)- 11 -

(5) Aquaculture Environments
The appropriate water temperature for yellowtail is 18 to 27°C. If the temperature
exceeds 28°C, feed intake drops, and at 32°C and above, fish may die. The appropriate
water temperature for greater amberjack is 20 to 31°C. At temperatures of 15°C or below
or 32°C or above, the fish cease to grow.
The salinity of seawater is about 30 to 33 psu, but the fish stop eating feed if it drops
to about 20 psu. (*psu is a unit indicating about how much salt is contained in seawater.
For example, 10 psu means that about 10 g of salt is contained in 1kg of seawater.)Normal seawater contains 6 to 8 mg/L of oxygen. Yellowtail and greater amberjack
move actively when the dissolved oxygen in the water ranges from 6 to 7 mg/L, and theirfood intake and growth suffer if it falls to 4mg/L or below.
(6) Aquaculture Facilities and Density
Aquaculture for both yellowtail and amberjack generally takes place in subdivided fishtanks. When viewed from above, the fish tanks used are square, and each side ranges
from 10 to 30 m. The depth of the fish tanks is generally 4 to 10 m.
As for the volume of the fish tank nets, generally density is 7 kg per m3. However, thewater temperature, dissolved oxygen content, tide speed, size of mesh and thickness ofmesh threads, and density are all adjusted with the growth of the fish.

(7) Fish Diseases and Countermeasures
Diseases known to be contracted by yellowtail and greater amberjack include bacterial
diseases (such as vibriosis, piscicida, nocardiosis, streptococcosis, mycobacteriosis, andgliding bacterial disease), parasitic diseases (such as Benedenia seriolae, white spot
disease, and heteraciniosis), and viral diseases (such as iridovirus).
Countermeasures for bacteria include the oral administration of antibacterial agents- 12 -

and antibiotics (for vibriosis, piscicida, and streptococcosis), but the usage ofpharmaceuticals is determined by law for each type of fish and disease, and these usage
regulations must be followed. There are also cases in which the infected fish must be
culled (such as infection with nocardiosis or mycobacteriosis).
As countermeasures for parasitic diseases, medicated baths (Benedenia seriolae) andfreshwater baths (Benedenia seriolae) are used, but if the dosage is wrong thesetreatments can actually end up killing the fish, so caution must be taken.
Vaccination is the only countermeasure for viral diseases. Commercial vaccines areadministered to the stomach of the fish when the fish weighs between 10 and 300 g.
Alternatively, commercial vaccines can also be orally administered when the fish weighs
between 50 to 500 g.

(8) Shipping
There are three methods used for shipping yellowtail and greater amberjack.
i. A method in which the fish are killed at the production site and shipped without
removing their organs (Fig. 8).
With this method, the fish are processed at the site of consumption.
ii. A method in which filleting takes place at the production site prior to shipping. The
fish are killed using ikejime, then the organs are removed, and the head is cut off (Fig.
9). Afterward, the fish is filleted into three pieces (Fig. 10). These fillets are thenvacuum-packed and sent to the sites of consumption.
iii. A method in which the fish is shipped alive from the site of production. In thismethod, a live fish truck or live fish vessel carries the fish from the site of production
to the site of consumption or a processing site near the site of consumption.

- 13 -

Fig. 9: RoundFig. 9: DressFig. 10: Fillet
6. Red Sea Bream Aquaculture
Red sea bream (Fig. 11) are distributed throughout Japan with the exception of
Okinawa, and inhabit not only Japan but also the East China Sea. They live at a depthof about 30 to 200 m along coasts. Their appetite begins to increase at 18°C or higher,
they are most active between 26 to 28°C, and they feed mainly on small crustaceans. The
spawning temperature is 18 to 20°C, and the Sea of Japan, the Pacific Ocean, the Seto
Inland Sea, and the western waters of Kyushu are known spawning grounds.

- 14 Fig. 11: Red sea bream(1) Securing Seeds for Aquaculture
Currently, only artificial seeds are used for red sea bream aquaculture. Maturation
can be promoted by controlling the water temperature, and the lengths of days can both
induce maturation and enable adjustment of spawning periods. To obtain fertilized red
sea bream eggs, mature female and male red sea breams are kept in an aquarium, andnatural fertilization takes place. Generally, an aquarium for adult fish is installed onland, and within that aquarium, sexual maturation is induced and spawning takes place.
In one spawning period for one fish, about 2 to 10 million eggs are produced. A fertilized
egg is about 1 mm in size, and the eggs are separated pelagic eggs which are circular inshape (Fig. 11). Hatching takes about 40 hours at around 19°C. A hatched larval fish
(Fig. 12) is around 2.5 mm in total length and exceeds 3 mm in total length 3 days after
hatching, at which time it opens its mouth and begins eating feed.

Figure 11: Red sea bream

Figure 12: Laval red sea

egg

bream

As the larval fish grow, the feed used progresses from marine Brachionus (such as
Brachionus plicatilis) (Fig. 13) to brine shrimp nauplii (Fig. 14), and then to mixed feed.

- 15 -

© Japan Fisheries Research and Education Agency© Japan Fisheries Research and Education

Figure 13: Brachionus plicatilis

Figure 14: Brine shrimp nauplii

Marine Brachionus are cultivated at seed production sites. Freshwater chlorella isused as feed for this cultivation, but since nutrition would be insufficient with only thisfeed source, the marine Brachionus are fed to the larval fish after nutritional fortification.
For brine shrimp nauplii, commercially available dried eggs are rehydrated inseawater and then hatch after about 24 hours. Brine shrimp nauplii also provide
insufficient nutrition, so they also undergo nutritional fortification before being fed to
the larval fish.
The red sea bream are cultivated in a land aquarium until they are about 10 to 30 mm
in total length. When they reach or exceed this size, they are moved to subdivided fishtanks on the sea, where cultivation continues. Moving the fish to fish tanks on the sea iscalled okidashi (moving offshore). The fish grow to a total length of about 50 mm about
90 days after hatching. During the period when their total length is between 10 and 50
mm, the fish are given mixed feed in accordance with their size. Generally, when the fish
exceed a total length of 50 mm, they are transferred from a seed producer to an
aquaculturist, where cultivation is continued.
In addition, the main feed used for small freshwater fish and fry is shown in Figs. 15
and 16.

- 16 -

© Tomo Kotani© Tomo Kotani

Figure 15: Copepoda

Figure 16: Water flea

(2) Aquaculture Methods after Starting Cultivation
Currently, live feed is almost never used alone, and dry pellets are mainly used.
Red sea bream feed more slowly than types of yellowtail, and it takes time for the feed
to be eaten. For this reason, the number of feedings must be increased, and sufficient
time must be provided for feeding. In addition, caution must be taken to provide only theamount of food that will be eaten to prevent feed from being left over in the tank.
(3) Aquaculture Environments
When the water temperature reaches 29°C or higher, the daily feed intake of red sea
bream changes significantly. Furthermore, red sea bream cease to eat much feed when
the temperature drops to 17°C or below, and at 10°C or below, they eat almost none.
Red sea bream cease to eat feed when the dissolved oxygen content falls below 4 mg/L,
abnormal behaviors appear when the amount drops to 3 mg/L or below, and they begin
to die off when the amount falls to 2 mg/L or below.

(4) Aquaculture Facilities and Density
Currently, aquaculture facilities often use subdivided fish tanks, and the shape and- 17 -

sizes of these tanks differ depending on the region. In waters with shallow depth, evenwhen using large square tanks with sides of 8 to 12 meters, the net depth is just 3.5 to
4.5 m. Offshore aquaculture is conducted with square tanks with 12 m sides and a depthof 12 m, or with circular tanks 20 m in diameter and 8 to 10 m deep.
Generally, the total weight of fish under 1 year old (fish born that year) should be 4 to
5 kg per m3 of fish tank volume, and when they have reached sufficient size for
harvesting (approximately 1,000 g), a maximum density of 8 kg/m3 is consideredappropriate.
However, while almost no disease is seen at densities of 3 kg/m3 or below, diseases
start to occur when density exceeds this level.

(5) Adjusting the Body Color of Red Sea Bream
There is a high likelihood of sunburn when cultivating red sea bream in shallow
waters; thus, a shading net is attached to the aquaculture fish tank to provide shade andprevent this. Furthermore, in order to make the red color of the red seam bream morevibrant, frozen krill, which is abundant in carotenoids (the main component of red
pigmentation), or a powdered extract is mixed into the feed.

- 18 -

Figure 15: Sea surface subdivided fish tank with a shading net attached(6) Fish Diseases and Countermeasures
Diseases known to be contracted by red sea bream include bacterial diseases (such as
vibriosis, gliding bacterial disease, Edwardsiella, and Epitheliocystis), parasitic diseases(such as white spot disease, bivagina tai, and skin fluke infection), and viral diseases(such as iridovirus and lymphocystis) are known.
As countermeasures for bacterial diseases, cultivating the fish in low-density
conditions (for vibriosis and gliding bacterial disease), administering antimicrobials (forvibriosis and Edwardsiella), and chemical (hydrogen peroxide agents) baths (for bivaginatai) are effective.
As countermeasures for parasites, oral administration of pharmaceuticals (lysozyme
chloride powders for white spot disease), moving fish tanks (for white spot disease),
freshwater baths (for skin fluke infection), and chemical (hydrogen peroxide agents)- 19 -

baths (for skin fluke infection) are effective.
Examples of countermeasures for viral diseases include the administration of vitamins
to enhance strength as a preventative measure, activation of immune system function
through the administration of immunostimulators, stress reduction, and cultivation in
low density environments. Recently, vaccination (for iridovirus) has also been conducted.
However, when a disease has appeared, prompt removal of the diseased or dead fish isthe best countermeasure. Furthermore, with regard to fisheries medicine, dosages anddirections to be followed are decided differently for each type of fish and type illness, sosuch medicines must be handled carefully.

(7) Shipping
Before shipping live red sea bream, feeding must be stopped a few days prior, allowing
the fish to eliminate all waste and completely empty their stomachs. This is done in orderto prevent worsening of the water quality during transportation. Furthermore, in order
to avoid damage to the mucosa and scales, it is also important to prevent fish fromrubbing against netting fabric or coming into contact with other fish during shipping.
The fish are placed in confined spaces when being transported, so sometimes they areallowed to become more accustomed to these spaces prior to shipping. Ships, trucks, andairplanes are used for the transportation of fish. For each of these, oxygen is supplied
when the water cannot be changed. Moreover, low-temperature and freezing processing
are conducted to lower the activity levels of the red sea bream.

- 20 -

7 . Fish Parts and Measuremen t
In order to learn abo ut the state o f the fi sh being cultiva ted, it isnecessary to learn a bout the size of fish . Howe ver , in order to learn
about size , i t is also necessary to learn a bout the names for fi sh parts.

(1) Names o f Fish Pa rts
At aquaculture sites , instructions for job activities may be given by
the names o f fish pa rts, so i t is importan t to me morize these names.

Dorsal fin
Caudal fin

Lateral line

Nose

Eye

MaxillaRostrum
Mandible

Branchia

Anus

Pectoral fin

Anal fin
Ventral fin- 21 -

(2) Fish Measurement
When measuring fish size, one of the foll owing is measured.
Total length : the l ength from the frontmost tip of the body to therearmost tip o f the c audal fin
Tail length: the le ngth from the frontmost tip of the rostr um of themaxilla to the most depressed part of th e caudal fin
Body length (standard body length): Th e length fro m the fro ntmost tipof the ros trum o f the upper jaw to the rea rmost tip of thevertebrae , or to the base of the caudal fi n

Total length
Tail length
Body length- 22 -

8. Ikejime Killing Method
This is a method in which a living fish is quickly killed and the freshness of the fish is
maintained by delaying rigor mortis. Ikejime may be conducted when shipping thecultivated fish. Furthermore, there are also various other killing methods which are used,such as nojime (immediate killing) and shinkeijime (destroying the spinal cord topreserve freshness). In the following photographs, incisions have been made at the head
and tail to drain the blood from the fish. In this way, it is also easy tell by looking at thefish that ikejime has been performed.

Ikejime performed on

Ikejime performed on aa red sea breamgreater amberjack

Ikejime performed on aflounder- 23 -