This is a strange question.
Fish cooking methods differ with fish type(name, age, sex, area), freshness and size.
This is the same even in your country. (Which country you living in?)
Whether bones, skin, or innards are attached is one of the methods of cooking.
Innards are basically removed, but many ovaries and hearts can be eaten without baking heats.
Although it is only limited species such as "Sanma" as not small fish,
https://en.wikipedia.org/wiki/Pacific_saurythis is due to innards structure and what they were eating, those were safer or not.
Reducing the freshness of fish is due to incomplete blood removal and rotting of innards.
Basically fishes in an environment with poor water quality are not delicious, it is same even in Japan.
Also, the Japanese are not eating only Japanese fishes, we also import fishes from abroad a lot.
We always study how to eat deliciously, no matter which country's fish.
Japanese dietary customs may support the health of your country.