In terms of preserving meat, I was wondering can you preserve fish in vinegar,
like pickled fish? Have you ever tried anything like that?

Preserving raw fish with raw vinegar for longer than 2 weeks with the same
recipe that pickles are made will completely disintegrate fish and you will
have a preserved fish soup. That fish soup will digest faster because it is
predigested and your body will use little or no enzymes for digestion.
Normal acidic intestinal bacteria can digest it quickly to make food for
us. However, most people do not want raw-fish soup, they want chewy fish.

Fish used for pickling commercially is cooked, processed and preserved to
the point that vinegar will no longer dissolve it. Also, the vinegar they
use is cooked and processed. The processing of raw fish for commercial
purposes hardens it, as if it is in formaldehyde-based chemicals. If
vinegar cannot dissolve your food, can your digestive juices (ideally 20%
of digestion) and intestinal bacteria (ideally 80% of digestion) dissolve
it? Can you imagine eating formaldehyde preserved fish? Stated humorously:
That is a choice. However, if you want chewy fish, I suggest you marinate
fish in vinegar and/or lemon juice from 1-24 hours, and pour off the
vinegar and/or lemon juice from 1-24 hours. Usually, that preserves fish
for 2-5 weeks, however after 2 weeks it may have a little rank odor.