Freshwater+fish+diseases

What is a parasite?
A parasite is an organism that lives in or on another larger organism of a different species (the host), upon which it depends for food. Although the parasite benefits from the association, the host is harmed. Depending on the species, the host/parasite relationship may be temporary or permanent. Bacteria and viruses are classified as parasites in some branches of biology.

Can parasites kill fish?
Parasites generally don't kill their hosts (it's a dumb parasite that kills its free lunch), but some can severely stress fish populations to the point of becoming biological and economical concerns. Parasites have a stake in the survival of their host. Sometimes, when parasites are numerous or the fish is stressed from another cause, the fish will die. Parasites can harm a fish by:
 * destroying tissue
 * removing blood and cellular fluids
 * diverting part of its nutrient supply
 * allowing secondary infections to develop

Do all fish have parasites?
Yes, in fact, parasitism is natural and normal. It occurs throughout the plant kingdom and in every major group of the animal kingdom. Usually, fish parasites aren’t noticeable, but sometimes fishermen will catch a fish with obvious signs of infection or parasitism.

Can I eat a diseased or parasite infected fish?
It is advisable to thoroughly cook or hot smoke all fish to 140° F for at least five minutes, or freeze them at 0° F for 48 hours. Although some parasites make fish look and taste unappetizing, very few fish parasites can be transferred to humans. Even when a fish exhibits obvious signs of disease or parasites, most likely the fish is still edible when cooked, hot smoked, or frozen. People have been infected with tapeworms (//Diphyllobothrium latum//) after consuming marinated, uncooked walleye and northern pike. In one incident, fishermen marinated freshly caught fish overnight in lemon juice and ate them the next day. They were following a recipe for //seviche//, a South American dish. Generally, Minnesotans don't prepare //seviche//, but they do pickle raw fish. Pickling alone may not destroy a larval tapeworm.

Yes! Fish secrete a mucous type coating over the entire length of their body that wards off fungal, viral, and bacterial infections. If this mucous coating is damaged, the fish becomes more susceptible to infection. Fishermen can help prevent infections by taking extra care when returning fish to the water. To protect the mucous coating, remove the hook while the fish is still in the water or wet your hands before handling the fish. Release the fish gently and as quickly as possible after the hook is removed.