Discussion in 'Fish' started by chef krimlar, May 3, 2015.

  1. chef krimlar

    chef krimlar Newbie

    All living organisms, including fish, can have parasites. Parasites are a natural occurrence, not contamination. They are as common in fish as insects are in fruits and vegetables. Parasites do not present a health concern in thoroughly cooked fish.

    Parasites become a concern when consumers eat raw or lightly preserved fish such as sashimi, sushi, ceviche, and gravlax. When preparing these products, use commercially frozen fish. Alternatively, freeze the fish to an internal temperature of -4°F for at least 7 days to kill any parasites that may be present. Home freezers are usually between 0°F and 10°F and may not be cold enough to kill the parasites.

    The health risk from parasites is far less than the risk from “unseen” illness causing bacteria which are present in almost all foods.
    Roundworms called nematodes are the most common parasite found in marine fishes. Some people call these nematodes herring worms or cod worms. Actually, several different species exist and it is hard to distinguish between them. All are in the family Anisakidae and are anisakid nematodes (see information below).

    Freshwater fish like trout and fish that spend part of their life in freshwater, such as salmon, may carry Diphyllobothrium tapeworm larvae (see information below). These small, whitish, and somewhat flabby worms are common in salmon from some areas of Alaska.

    The life cycle of an anisakid nematode begins when seals or sea lions eat infected fish The larval nematodes grow to maturity, and the marine mammal excretes the nematode eggs into the sea where they hatch. Shrimp-like animals eat the larvae, and fish eat the shrimp . The larvae then develop into the form we see in fish.

    The life cycle for a tapeworm is similar. Mammals or birds eat infected fish. The eggs hatch in freshwater. Crustaceans eat the eggs, freshwater and anadromous fish eat the crustaceans, and we eat the fish.

    Many consumers prefer the delicate flavor and texture of uncooked fish found in sushi and sashimi (thin slices of raw finfish) dishes. But there should be caution in consuming raw fish because some species of fish can contain these harmful worms. Eating raw, lightly cured, or insufficiently cooked infected fish can transfer the live worms to humans. Most of these parasites cannot adapt to human hosts. Often, if an infected fish is eaten, the parasites may be digested with no ill effects. Adequate freezing or cooking fish will kill any parasites that may be present. Raw fish (such as sushi or sashimi) or foods made with raw fish (such as ceviche) are more likely to contain parasites or bacteria than foods made from cooked fish, so it's important to cook fish thoroughly (at least 145°F for 15 seconds) or use commercially frozen seafood in raw dishes.

    Two types of parasitic worms can infect humans:

    1. Anisakiasis is caused by ingesting the larvae of several types of roundworm which are found in saltwater fish such as cod, plaice, halibut, rockfish, herring, Pollock, sea bass and flounder.

    2. Tapeworm infections occur after ingesting the larvae of diphyllobothrium which is found in freshwater fish such as pike, perch and anadromous (fresh-saltwater) fish such as salmon.

    During commercial freezing fish is frozen solid at a temperature of -35°F and stored at this temperature or below for a minimum of 15 hours to kill parasites. Most home freezers have temperatures at 0°F to 10°F and may not be cold enough to kill parasites because it can take up to 7 days at -4°F or below to kill parasites, especially in large fish. Good handling practices on-board fishing vessels and in processing plants can minimize nematode infestation. Many seafood processors inspect seafood fillets of species likely to contain parasites. This process called candling involves examining fish fillets over lights. Candling detects surface parasites. Unfortunately, they cannot always see parasites embedded deep in thick fillets or in dark tissue. Candling is also useful for revealing pinbones in fillets that are intended to be boneless.

    Fish is also safe to eat after it is cooked to an internal temperature of 145°F for 15 seconds. Normal cooking procedures generally exceed this temperature. If a thermometer is not available to check the internal temperature of the thickest portion of the fish, the fish should be cooked until it loses its translucency and flakes easily with a fork.
  2. chef krimlar

    chef krimlar Newbie

    I Love Sashimi, always have ,always will ! Love oysters on the shell also ! Homemade smoked salmon is like candy to me ,any cured or smoked salmon is also a delight ! If processed and cut(trimmed), de-boned) ; a whole fresh salmon filet will cure and smoke well in a properly setup situation within 5 days days of catch.
    Last edited: May 3, 2015
  3. After what you posted sure makes me glad I only use raw fish as cut bait!  I never did understand the love of eating raw fish.

    But I'm with you on oysters on the half shell!
  4. threemuch

    threemuch Fire Starter

    So raw fish is icky, but the rock you pried open that had a salty loogey inside is OK.  Even though that loogey is a filter feeder and may be contaminated with the waste of whatever recently defecated in the water it resides in and could also give you naturally occuring toxins that could give you paralyitic shellfish poisoning or amnesic shellfish poisoning because it ate the wrong flavor diatoms.  I love em both, but the risk is NOT lower in shellfish than finfish.

    The fish I eat raw are salmon, tuna, and yellowtail.  I candle the fish generally rather than freezing. We see tons of anasakids in benthic fish.  I don't eat those raw, but we frequently prepare halibut "medium rare" where it's translucent in the middle.  That I make sure get's a week a freeze before we eat it.

    No parasites yet.  Been eating raw seafood I catch myself for 20 years.

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