First, where did you buy your fish? If it was supermarket it was already old when you bought it. That ammonia smell you pick up when you are standing there at the fish counter is the scent of decomposing fish. Second, what type of fish? Some keep longer than others. Shellfish (such as "fresh" scallops) go off really, really fast. Steakier fish you can keep longer but maybe only 24 hours longer.

Bring it home and cook it the same day.

I'm with the majority here. two to three days, re-wrapped (don't leave it in the store's wrappings) and sitting atop a bowl of ice water. Learned this one from Julia, herself. But it only makes sense not to keep fish more than three days.

Don't rely on your nose.

I store for 1 to 2 days max on ice in the fridge as thirschfeld said. My fishmonger recommended no more than 2 days.

fillet the fish as required size wash well rub with pepper no salt keep in small airtight containers(Tupperware) and freeze. You can keep this for 7 to 8days

It depends on how fresh it was when you bought it. You also want to keep it on ice but not directly on ice. Meaning place some plastic wrap between the ice and the skin side of the fish. Usually three to five days. You can rinse the fish each day but there are some fish you don't want to do this to, like tuna, because you will wash away natural oils that help to keep it fresh.

Two days is my max.

Well, you know what they say: fish and visitors stink after 3 days!