Remove the fish from the fridge and clean up any spilled juices using paper towels and a watery cleaning paste made with water and baking soda. Wet a paper towel with water and wipe the water paste clean.
Fill small shallow bowls with about 1/4 cup of dry coffee grounds, new or used. Fill enough bowls to place one on each shelf and one in each drawer. If you are using used coffee grounds that are still wet, spread them out on a plate or another surface to dry first.
Place one bowl of coffee grounds on the center of each shelf and in each drawer and leave them there for three or four days.
Smell the refrigerator in three or four days. If the fish smell is gone, take out the coffee grounds. If it's still present, leave the coffee grounds in there for another three or four days.
Wash the fridge out, if desired, if it smells like coffee grounds several days after removal. Empty the fridge and use the baking soda cleaner described in Step 1 to wipe down the inside.