Not a good idea, particularly since they are fish and spoil quickly.
if it has been left out over night or has been put in the fridge without the lid on
Yes ofcourse
No - any food not eaten within an hour should be thrown out - and fresh put in the following day.
leave it outside
Chicken is never okay outside of the fridge or freezer. If it's left out more than 20 or 30 minutes, I would throw it out.
In a sealed bowl in the fridge for 4-5 days at most.
Bacteria will start to form on foods left out over an hour.
Transfer it to a bowl, cover it and place it in a fridge
yes :)
You bet.
yes
Yes. You can eat left over Pizza. Only if you put it in the refrigerator. If you leave it out like on the stove or something you might get sick.