I have a pack of fish in the fridge that says cook from frozen, is it safe to cook now it has defrosted. I have had it for one day in the fridge
Yes it is safe. You might have to adjust the cooking timing that is suggested though.
It is safe, but I would not leave it in the fridge much more than one day. Also make certain it is fully cooked through. If you like your fish a bit rare, but fresh and cook as soon as possible.