Vinegar does help remove fish odor.
You can use vinegar to remove fish odor from your hands, countertop, cutting board and even clean your oven out with some vinegar to help remove the fishy odor.
An oven can smell like fish when you bake fish and then the fish smell can get into the leftover grease that can be in your oven.
Also you may sometimes notice a smell of fish in your oven even if you don't bake fish as the grease which can be hidden in the oven can stagnate and start smelling fishy.
Other types of grease mixing together in the oven from different foods being cooked such as beef, chicken, steak etc can cause the grease to smell fishy or other rotten smelling the longer the grease sits in the oven.
When cleaning an oven you should use some easy off oven cleaner which helps to dissolve the grease fast and helps to get rid of all the grease.
Make sure to use a scrub brush and some hot water to clean the oven out after wiping most of the grease away using the easy off oven cleaner.
You can also then use some vinegar and baking soda and hot water to clean the oven.
Grease deposits in the oven tend to be the main culprit of an oven smelling like fish because the puddles of forgotten fat find and trap odors in the oven and ferment them over time which leads to the foul smell and fishy smell.
You should clean your oven out at least once per month or once every 2 weeks depending on how often you use the oven.
If you do have greasy or oily foods spilling in the oven you should wipe out the grease after the oven cools down so that the grease does not have time to ferment and start smelling.