Camallanus is an intestinal parasitic infection. This malady is due to a nematode or parasitic
worm which is found in wild fresh and salt water fishes throughout the world . The infestation is characterized
by, among other things, the presence of tiny red thread structures protruding from the anus of
the infected host fish. Close inspection of the victim shows a swollen and irritated vent area. The worms
actually protrude 1/3 to 1/2 inch from the anus of the infected fish. This is about one fourth to one third
of the worm’s length. The worms are red from the victim’s blood in their gut.
As with most parasites, there are two main body functions of this worm, reproduction and nourishment.
The attachment inside the fishes gut is by what appears to be a simple row of long hooks.
Closer examination revels a burr like structure. Attachment to the intestinal wall causes considerable
damage to the host’s intestines. The remainder of the body of the worm is dedicated to reproduction.
Microscopic larvae from this parasite are constantly being produced and dumped into the water. A
secondary host is necessary to carry on the life cycle. But, once established in the copepods found in
most of our tanks, the nematode infection is easily transferred from hobbyist’s aquarium to aquarium
with nets, feeding utensils, water change devices and simple aspiration of splashes and spray from one
tank to another. This carries the infection rapidly around the hobbyists’ fish room in a matter of days.
The early signs of the parasite’s presence are typically unnoticed. The victims show a minor
swelling of the belly and may go off their food. Usually the fish have no problems laying eggs until the
infection has reached the stage of showing protrusion from the anus. In the end, the anus and reproductive
organs of the fish become so irritated and inflamed that secondary infection sets in and the swelling
causes enough hemorrhaging to cause the victim to bleed to death or it dies from internal bacterial
infection. In addition to this obvious outside appearance, the worm has been found in the body cavity
of infected hosts. This may explain some of the mysterious deaths one sees in fishes which have been
successfully treated for the nematode. The adult worm has died inside the body cavity and decayed
inside the host fish. Sounds gruesome!
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