Once fish has been thawed in the refrigerator, it can typically stay in the fridge for an additional 1 to 2 days before it should be cooked or consumed. This assumes that the fish was properly thawed in the refrigerator and not at room temperature.
The total time fish can be stored in the refrigerator, including both thawing and storage time, should not exceed 1 to 2 days. If you don't plan to cook or eat the fish within this time frame, it's best to refreeze it or cook it and then store the cooked fish in the refrigerator for an additional 1 to 2 days.
Always ensure that the fish is properly wrapped or stored in an airtight container to prevent cross-contamination with other foods and to maintain its quality and safety. Additionally, use your best judgment and your senses (smell and appearance) to determine if the fish is still fresh and safe to eat. If you have any doubts, it's better to err on the side of caution and discard the fish.