It is not safe to eat cooked fish that was left out overnight.
Even when the fish is cooked the cooked fish left out overnight can still grow bacteria rapidly and make you sick.
If you've left cooked fish out overnight it should be thrown out and not consumed.
If you have leftover cooked fish it should be refrigerated within 2 hours of cooking it to prevent bacteria from growing on the fish.
Even if the cooked fish smells fine it can still be unsafe to eat.
Never leave any cooked meats or other perishable foods out of the refrigerator for longer than 2 hours as it can make you sick.
It is not safe to leave cooked fish or other cooked meat out overnight.
Raw fish should not be left out of the refrigerator or freezer longer than 30 minutes or it can spoil and grow bacteria.
Raw fish and raw meats will last 6 months to a year in the freezer but only a few days or so in the refrigerator.
Throw out any meat even if it was cooked if it was left out overnight or for a few hours.
The risk is not worth it and it can make you really sick and can even kill you in some cases.