Possibly good Information from Cook's Illustrated:

Published March 1, 2005.

What's the best way to keep fish fresh?


Because fish is so perishable, it's best to buy it the day it will be cooked. But that's not always possible, even here in the kitchen. Here's what to do if you need to hold fish beyond the day it's purchased.

As soon as the fish gets into the kitchen, unwrap it, pat it dry, put it in a zipper-lock bag, press out the air, and seal the bag. Then set the fish on a bed of ice in a bowl or other deep container (that can contain the water once the ice melts) and place the bowl in the back of the fridge, where it is coldest. If the ice melts before you use the fish, replenish it. Another option is to set the patted-dry fish in a container or bowl or on a plate, press plastic wrap directly against the surface, and place frozen reusable ice packs on top. Either way, the fish should keep for one day.