Since refrigerators are air tight, any odours that come about because of rotten or smelly food can and will linger even after you remove the source of the odour. Fish has an especially pungent odour and can cause changes in the smell and taste of other foods in the refrigerator. In order to eliminate all traces of the fish smell, you will need to clean the fridge out as well as use something to absorb the odour in the air.
Remove all food from the refrigerator. Slide each shelf out and unplug the unit.
Fill a bucket with hot water and a few tablespoons of dish soap.
Clean the entire inside of the refrigerator out using a scrubber sponge with the hot soapy water. Scrub the sponge in small, circular motions over the walls and the inside of the door.
Wipe the inside of the refrigerator dry using a clean towel.
Replace the shelves and food to the refrigerator.
Place an open box of high quality baking soda somewhere in the refrigerator. The baking soda will absorb any odours left over in the air from the fish.