The bluefin tuna goes by different names in Japanese depending on its age. It starts out as “Meji (メジ or メジマグロ),” grows into “Chubou (中坊)” and finally is called Maguro (once it’s 50 kg or more).
Meji is less than 1 year old and weighs around 20 kg.
Chubou is an old word for relatively low-class Buddhist priests who were treated as errand boys. I guess it was meant to imply that these boys were even weaker than tuna. At this stage, the fish are between 2-5 years old and weigh about 40kg.
Anything larger than that is called Maguro. The biggest is 3m long and 600kg or more. Especially large tuna is called Shibi. “Shibi” comes from the Japanese characters for “4-days”, which is how long the fish takes to mature.
Most Meji and Chubou are caught from May until the beginning of autumn when Maguro is thin and tasty.
Meji has a unique scent and taste that sets it apart from full-grown tuna. The color is similar to the skipjack rather than bluefin. On the other hand, Chubou has a lighter color and it isn’t as rich, but the flavor is young, refreshing tuna. That is why Meji is considered to be a completely separate sushi topping and Chubou is presented to be a type of tuna.
We hope this information will be helpful.
Revision date: May 4, 2021