All raw meats contain bacteria, and some fish may even be host to certain parasites - not a good idea for consuming raw. It is recommended that fish be frozen then thawed before consumption to kill whatever bacteria or parasites that may be present.
The sashimi grade raw fish for sale in the supermarkets is taken from fish that was frozen almost immediately after it was caught. As huge commercial freezers that can freeze fish at -40 degree Celsius are used, any bacteria or parasites would be killed within 24 hours. Even so, if the sashimi is not handled properly during the journey and after you reach home, contamination may occur and it would still be very risky for you to eat it raw.
However, as our refrigerators at home are not capable of doing that, it may take up to 3 or 5 days of freezing before the same results can be achieved. If you have decided to consume your catch raw, try the following:
1. Process the fish as soon as possible after you catch it. Kill it immediately by cutting the gills and throat area and allowing blood to drain out.
2. Gut and fillet and remove the skin of the fish. Make sure that your hands and whatever utensils that you are using are completely clean. If conditions permit, wash hands with soap and warm water, and all utensils with soap and hot water before and after use.
3. Hold the fillets up against a bright light. This is known as candling, a method that allows you to see parasites, larvae or even eggs that are embedded in the flesh of the fish. Remove with tweezers if any are found.
4. Wrap the fillets separately in clean water-proof plastic bags. Cover entirely with ice, or place inside freezer and leave for at least 3 days.
5. Never defrost fish at room temperature. Allow fish to defrost slowly in the chiller to avoid the temperature danger zone (between 5oC to 60oC) that encourages bacteria growth.
6. Cut the fish into thin slices, again making sure that your hands are clean and using absolutely clean utensils.
7. Serve immediately on clean plates.
Warning: Unlike healthy adults, people with weaker immune systems (e.g. infants, pregnant women and the elderly) might have to refrain from consuming raw fish.
