Secure and safe farm-raising yellowtail and distribution which are grown in Amakusa sea

Operation procedure

Introducing fish juveniles


【For yellowtail (Buri) and amberjack (Kampachi)】Introducing fish juveniles
Mojyako (fish juveniles) are seedlings (juveniles) of yellowtail (Buri/Hamachi). The name originated from Jyako which can be found under algae which are floating in the ocean current of the south of the East China Sea. The seedlings of yellowtail said to be born in the south of East China Sea instead of the artificial hatching program. We go to the East China Sea to collect these seedlings around April and May in order to farm raise Mojyako then, to grow inside quiet bays in Kyusyu.

【Horse mackerel (Shimaaji) and Sea bream (Tai)】 Unlike yellowtail, horse mackerel and sea bream juveniles are born in artificial hatching program by producers. They do not originate from natural resources.



Feeding is to let the juveniles get used to nutritious food made by us from eating planktons in the sea. Just like baby food for us!

Selection by weight


By selecting the fish with the same weight at the time of juvenile stage, the fish growth will become uniform. The fish with sickness will be eliminated at this stage as well.

Net changing and cleaning

The nets left under the water for a long time will naturally build up with seaweeds or shells. If this condition continued, the fish will have a lack of oxygen as no fresh ocean water will come in. The regular cleaning of the nets can avoid this from happening. Also, the maintenance of the nets as well as checking the fish conditions will be conducted to detect sickness or the escaping fish.



Fish has no difference from human babies when it comes to vaccination. Fish will be born with some immunity however, when a certain period of time passes, the fish can be exposed to any sickness. The vaccination helps to prevent from sickness as well as excess use of antibiotic.

Disinfestation (disinfection)

The body of the yellowtail is covered by mucous membrane instead of scales. So parasites are easily found on the body and sometimes the fish develop other sickness due to the parasites. Disinfection can prevent this. However, we won’t use any chemicals. The fish are simply left to swim in fresh water. These kinds of parasites will die off as soon as they are in fresh water.



Nourishing is to feed the fish. However, this nourishing stage is to feed the fish according to preserves and consideration of nutrition.  The current, water temperature, fish conditions are to be considered to ensure the fish will grow effectively and minimise the waste of food. Also, to avoid feeding the same food all the time that food will be changed regularly. The daily study is carried out to nourish the fish as naturally as possible. Quality management of the fish are carried out from the origin of food to analysing nutrition in the farming stage.


Although, the fish health is closely monitored, the fish might get sick just like each one of us catching a cold. If one fish becomes sick this will prevail very quickly and it leads to death. The medication is the last resort to prevent this from happening. Our focus is always on the preventative measures such as food and environment managements. 

Spawning preparation – Spawning – Recovering

As fish is nature oriented seedlings, genetic modification or hybrid can not be conducted. Therefore they lay eggs by instinct. Spawning preparation period will be around one year and a half after starting farming. The sacs of the eggs will only be the size of the top of the chopsticks. During the spawning period it will grow big, some of them will grow the size of a fist which is after one year and 10 months or so. Recovering takes time after spawning. The food the fish eats will stop going into the fish’s stomach to help only eggs grow larger before the spawning period. However, the food starts going into the fish’s stomach after spawning period but the quality of the fish meat will be unstable while the size of the stomach gets back to normal.  We call it recovering period during this time. The fish freshness might be good but putting fats and discolouration of the meat occur rapidly.    The fish put their energy (fattiness) into their eggs to nourish them. The fish after spawning period use up all their energy (fattiness) and begin to waste away.

Colouring  【Sea bream】

Sea bream get sunburn just like us even under the water. That’s why we put light blocking nets over the preserves to avoid direct sun and sunburn. Also, food given is mixed with prawns or crabs to get the distinctive colour of red of sea bream.



This is to land fish from the preserves, apply ikijime then send off to the processing plant. Ikijime is to kill fish instantly by hooking up a hand hook into the fish head. It is cruel but this is the best way to keep the fish fresh. The fish after ikijime are put into ice water to cool and then transferred to the processing plant. The transferring time takes one hour at the longest. The freshness remains for processing.

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