Keep butterfish cool on the trip from the market to your house. Never let it stay unrefrigerated for long. To store butterfish, remove packaging, rinse the fish under cold water, and pat dry with paper towels. Fish deteriorates when it sits in its own juices, so place it on a cake rack in a shallow saucepan filled with crushed ice. Cover with cling wrap or foil and set in the coldest part of the refrigerator. Butterfish will store well this way for up to two days. When well-wrapped, butterfish can be frozen for up to two months in a refrigerator and for three to four months in a deep-freeze. Use lined freezer paper, and wrap fish tightly from head to tail with at least two layers of paper. To thaw slowly, unwrap, place in saucepan, cover, and leave for 24 hours in the refrigerator. To thaw faster, place the whole fish (wrapped in a watertight bag) in a sink with cool running water, allowing about 30 minutes per pound (450g). For the fastest thaw, use the defrost cycle of your microwave, allowing two to five minutes per pound (450g), with equal standing time in between zaps (as one minute defrost to one minute resting).