Learn Italian: Non ho ancora assaggiato nemmeno il pesce crudo.

In Italian, when a negative word like nemmeno (not even) comes after the verb, you must put non before the verb. This creates a "double negative" that is perfectly correct in Italian and doesn't cancel itself out like it would in English.

Could I use neanche or neppure instead of nemmeno here?

Yes! Neanche, nemmeno, and neppure all mean "not even" and are completely interchangeable. Saying non ho ancora assaggiato neanche il pesce crudo means exactly the same thing.

Why does nemmeno go right before il pesce crudo?

Nemmeno is placed directly in front of the specific word or phrase it is emphasizing. Here, the speaker is highlighting the raw fish as the thing they haven't tried, so nemmeno sits right next to il pesce crudo.

Why is ancora placed right in the middle of the verb (ho ancora assaggiato)?

Short adverbs of time like ancora (yet/still), già (already), and mai (ever/never) usually go right between the helper verb (like ho) and the past participle (like assaggiato) in compound tenses.