Common Name:  Flukes (Skin, Gill, or Eye)

Pathogen/Cause: Dactylogyrus vastator (Gill Fluke), Gyrodactylus sp. (Mostly Skin Flukes), etc.

Physical Signs: Gill flukes may show with red, inflamed gills, but otherwise many fish flukes are microscopic (some of the largest being just a few mm, but mostly smaller), and so confirmed diagnosis by physical appearence alone is not possible. Confirm with a vet or lab.

Behavioral Signs: Scratching, gasping at surface (again a nonspecific sign that has other more common causes, see comments at right).

Potential Treatment: A good, thorough discussion of treatment options can be found in Dan's archived comments on fluke treatment.

Other Notes: No photos are included here, because usually flukes are too small to visualize with the naked eye. This also creates serious problems for trying to diagnose by general physical signs (hyperproduction of slime, inflamed gills) or general behavioral signs (listlessness, gasping, scratching, etc.). All these signs overlap considerably with other more common causes of skin and gill irritation, including ammonia poisoning and more common skin parasitisms such as ich. The first step in any tank where these signs are seen is to rule out ammonia poisoning first by testing for any level above 0.

Common Name:  Roundworms

Pathogen/Cause: Unknown nematode species (metacercarean form)

Physical Signs: As shown below as an infection of connective tissue (usually internal worm infections cannot be seen externally and often affect the gut; in these cases, they have migrated to muscle tissue).

Behavioral Signs: Loss of appetite, lethargy, etc.

Potential Treatment: Try Clout or an antiparastic medication for large parasites (formalin and many methods were tried on the first cases below without success). There is also some good information on the treatment of camallanus worms as contributed by Jason Parry.

Other Notes: Please read my article, Worms in my tank?? before jumping to the conclusion that any worm in the tank is a parasitic or disease causing worm. The large majority of small worms seen in the aquarium not attached to the fish are free-living and harmless (the ones shown below are an obvious exception). Most of these true parasites shown below require a fish host at some time in their life cycle. They often come in with contaminated live foods such as Tubifex worms.