With regard to this issue, the follower (ordinary Muslim) must follow an 'alim who advises him to follow either of these two opinions.

It is not haram to be vegan by not eating animal products as long as you do not think that these things are haram or that it is better to abstain from these foods.

Some scholars said that it is disliked to eat raw meat, but the correct view is that it is permissible because all things are permitted except those which have been expressly forbidden.

All kinds of food from the sea are permissible, whether they are plants or animals, alive or dead. There are certain types of water animals which are forbidden such as crocodiles, frogs, otters and turtles. For more, please see the detailed answer.

Allah has permitted us all the produce of the sea. So, all parts of the fish are halal, including its skin, tail, eyes, etc.