Related FAQ: Marine Parasitic Disease, Parasitic Disease 2, Parasitic Disease 3, Parasitic Disease 4, Parasitic Disease 5, Parasitic Disease 6, Parasitic Disease 7, Parasitic Disease 8, Parasitic Disease 9, Parasitic Disease 10, Parasitic Disease 11, & FAQs on: Parasite-infested Systems: Parasitic Marine Tanks, Parasitic Marine Tanks 2, Parasitic Reef Tanks, Parasitic Reef Tanks 2, & FAQs on: Preventing Parasite Problems, Diagnosing Parasitic Diseases, References on Parasitic Diseases, Index Materia Medici for Parasitic Diseases (medicines), Treating Marine Parasitic Diseases, Using Hyposalinity to Treat Marine Parasitic Diseases, Hyposalinity Treatments 2, Fallow Tanks, & Best Crypt FAQs, Cryptocaryoniasis, Marine Ich, Marine Velvet Disease Biological Cleaners, Treating Parasitic Disease, Using Hyposalinity to Treat Parasitic Disease, Parasitic Worms, Crustacean Parasitic Disease, Isopods, Cryptocaryoniasis, Marine Ich, Marine Velvet Disease, Treating Parasitic Disease I & Treating Parasitic Disease 2, Fish Worms Diseases,  Related Articles: Parasitic Disease of Cultured Fishes (overview), The Three Sets of Factors That Determine Livestock Health/Disease, A Livestock Treatment System, Marine Ich (Cryptocaryoniasis), Velvet (Amyloodiniumiasis), Brooklynellosis, Isopods, Biological Cleaners, Treating Parasitic Disease, Using Hyposalinity to Treat Parasitic Disease, Fish Worm Diseases,  Marine Aquarium Fish Parasitic Diseases

Bob Fenner

A Diagramma pictum with a couple of parasitic isopods on its head

So you think your fishes have been stricken by a parasitic invasion? Better check that their environment isn't the cause of all that scratching and thrashing about before dumping in X, Y, Z super medicines.

Almost all marine livestock is wild caught and typically carries some internal and external parasitic "load". With proper, timely handling the bulk of these protozoans, worms, crustaceans, et al., can be "knocked off" and/or reduced in virulence without impugning the health of your livestock.

Here's my "parade of the stars", the most commonly encountered and written about captive marine parasitic fauna, with a few more notes on treatment and eradication.

Some general signs of a parasite infestation are:

1) Visible spots, threads, usually whitish, that make the fish look like it has been salted or covered with powdered sugar.

2) Rapid or heavy breathing. Some parasites will attack the gills before any can be seen on the fins or body, and the fish may die from suffocation.

3) Scratching. If a fish constantly rubs against objects in the tank and looks like it is trying to dislodge something it may be parasites.

4) Lethargy. Are your fishes, "laying about", having "private parties" in the corners; with their fins retracted? This is certainly a bad sign.

The Players: A Listing:

To poorly mis-quote, "All those marines have little fleas upon their backs to bite them, and those fleas have littler fleas, and so ad infinitum" Dear Reader and harsh critics, I know this is a whole bunch of new and strange information; and that it's only a little of what is known; which is a mere smidgen of what is to be learned. Bear with me though, as we must tally this conglomeration.

Protozoans

These are the single celled animals we call flagellates, ciliates, sporozoans and more. The two most deadly parasites, saltwater "ich", Cryptocaryon, and marine "velvet", Amyloodinium are protozoans. These are the most lethal coral reef diseases for marine aquarists, too often responsible for large and fast loss of fish livestock.

Amyloodinium ocellatum is a flagellate protozoan or a dinoflagellate algae depending on whether you're a zoologist or botanist-leaning classifier; in older texts it's called Oodinium.

This parasite infests the gills and body surface of fish hosts; appearing as a velvety sprinkling. Behavior of fishes includes dashing, scratching, rapidly breathing until so much damage occurs to their gills that they become lethargic and die.

Cryptocaryon irritans Cryptocaryon irritans is the causative agent for marine ich, or white spot disease. It is a ciliated protozoan, named for it's many small cilia utilized for locomotion. We'll include in it's discussion two other ciliate protozoans, Brooklynella hostilis, so called Anemonefish disease (though it infects all marine bony fishes), and Uronema marinum (Uronema). All three organisms produce similar observable signs, are deadly, spreadable, and cured and prevented through about the same means. is the causative agent for marine ich, or white spot disease.

The rapid production of mucus showing up as clumps are close to the last clue you'll get before your fishes breakdown with rapid then lethargic breathing. Uronema may reveal itself in ulcerations that look like lesions.

General Treatment Against Protozoan Parasites

Affected individuals must be isolated and treated ASAP. General procedure calls for dipping/baths, possibly lowering specific gravity, and continuous exposure to 0.10-0.15 ppm copper. Antibiotic feeding is recommended to prevent secondary infection.

And you're not done yet. If protozoan parasites show themselves in your main system, very likely they have reproduced and left resting, non-feeding stages of progeny in the water and on the substrate. Oh joy. Getting rid of these can be a real pain.

At the very least, allowing the system to "go fallow" without hosts for a month (or more) has proven to reduce numbers and disease-causing-strength (aka virulence) sufficiently. At the worst, you're looking at tearing down, sterilizing and re-assembling the entire system. Now are you convinced as to the value of prevention, particularly quarantine?

Other Protozoa

Let's not leave out mention of the protozoan groups Microsporea and Myxosporea. These are all obligate parasites, many of which infest (external) and infect (internal) fishes and invertebrates. Of the microsporeans, Glugea is notable as the gunky cyst-like disease of seahorses, pipefishes and their relatives. Myxosporea are also tiny, found either living within host tissues or their body cavity. There is no known cure for these protozoans.

Crustaceans

Many of these look nothing like the familiar crabs or shrimp; hence their "worm" and other common names.

Isopods, the "pill-bugs" or Rollie-pollies of your childhood are not so funny when they show up in your marine system. These crustaceans with "all about the same feet" are big enough to see and remove from the fish's mouth or body with forceps/tweezers.

Copepods: Copepods: looking more worm-like than anything; there are more than one thousand species of parasitic copepod crustaceans known. Some of them are very common and can be debilitating or lethal in large numbers. looking more worm-like than anything; there are more than one thousand species of parasitic copepod crustaceans known. Some of them are very common and can be debilitating or lethal in large numbers.

These copepods are specialized in their structure and feeding; some are internal with bizarre sac-like and tree-branching body shapes, External species range from forms with holdfasts that permanently wedge them into their host's integument to one's that range over the body surface with specialized cutting, puncturing and sucking mouth parts.

The copepods that can be treated (those on the outside of their hosts) are best eliminated through freshwater dips and copper treatment as the fishes pass through quarantine. Biological cleaning by certain shrimp, gobies and wrasses presumably aids in restricting copepod parasitism in the wild.

Worms

Phylum Platyhelminthes; flatworms, flukes, tapeworms.

Turbellarians, a group in the flatworm Phylum Platyhelminthes are mostly "free-living" non-parasitic species. One notable exception is Paravortex, the causative agent of "black spot disease", notably of yellow tangs. This is easily eliminated via freshwater dipping, though other authors suggest formalin baths and organophosphate remedies. Turbellarians, a group in the flatworm Phylum Platyhelminthes are mostly "free-living" non-parasitic species. One notable exception is Paravortex, the causative agent of "black spot disease", notably of yellow tangs. This is easily eliminated via freshwater dipping, though other authors suggest formalin baths and organophosphate remedies.

Trematodes, the flukes are divided into ecto-parasitic (external) monogenes and the largely endo-parasitic (internal) digenes on the basis of their life histories. Monogeneans have a direct life cycle, and digeneans an indirect one with the use of one or more intermediary host species. The monogenes are important as gill and body parasites of marine fishes.

There are many species of flukes, they are common on imported livestock, and may significantly reduce their health if not eliminated through acclimation techniques. Hiding, rapid breathing discoloration and more are symptomatic of infection/infestation, though microscopic examination of skin scrapings and gill clippings are required for positive diagnosis.

Several chemicals including organophosphates, copper, quinines and dips of freshwater with/out malachite/formalin have been described in the literature as being efficacious. Recent authors tout the use of Praziquantel (Droncit (R)) at 1ppm in a treatment system.

Digeneans rarely spread due to the absence of intermediaries, and many of the monogenes are species/group specific.

Cestodes: Cestodes are the tapeworms that live in digestive systems;

yes, fishes get them as well as farm animals and you and I. Typically an aquarist will only become aware of their presence through a section of a worm being expelled from the vent, or from post-mortem dissection.

Fishes are either imported with the tapes or pick them up from ingesting their intermediate hosts; in their food. Once more, a good reason to not-use live marine foods.

There are anti-worm chemicals that work on ridding fishes of intestinal parasites; you can check with local sources as to which is the "latest and greatest" available; but I wouldn't. The vast majority of incidents show that the cure is too late, or more deadly than the problem. Well maintained specimens have "successful" relationships with their internal parasites; they're not killed by them.

Roundworms, the Phylum Nematoda Roundworms, the Phylum Nematoda like the tapes, are rarely encountered unless detected protruding from a fish's vent or from cutting up a specimen after it has died. Many are microscopic, some macro- as parasites. Amongst all "worm" groups a nematode is easy to recognize by it's tri-radiate esophagus, otherwise they're typically smooth, white, and non-descript. like the tapes, are rarely encountered unless detected protruding from a fish's vent or from cutting up a specimen after it has died. Many are microscopic, some macro- as parasites. Amongst all "worm" groups a nematode is easy to recognize by it's tri-radiate esophagus, otherwise they're typically smooth, white, and non-descript.

With this worm group the best treatment is none at all; simply optimizing the environment reduces the likelihood of loss or debilitation from roundworms. If you have an aquaculture facility or many members of the same species that are determined to be dying from nematodes, anthelminthics (Piperazine, Levamisol (both in Discomed (tm)) the family of chemicals called Benzimidizoles, et al. are efficacious).

Summary:

There are no "health standards" imposed by law on the collection, holding, wholesale, retail, end-user treatment of marine livestock. It is up to each individual handling this aquatic life to do their bit in terms of sanitation and quarantine procedures.

The only way to "get value" as with everything else in life is 1) to know it, and 2) demand it, or 3) provide it. You will find that in keeping a marine system this comes down to study, earnest involvement with dealers, and conscientious care.

What little is popularly known regarding aquatic parasites has largely come from studying "food-fish specimens found pickled in scientific collections". I mean it's mainly baseline descriptive, "what's that" information that is of little practical value to aquarists. We don't have tons of the same cultured species, with veterinary staff and a laboratory; we just want to get rid of problem parasites pronto. Future aquarists will do much to unfold the mysteries of life history and control of these organisms.

Bibliography/Further Reading:

Anderson, James A. 1989. Worm infestations in fish. SeaScope vol.6/89.

Bassleer, Gerald. 1983. Uronema marinum, a new and common parasite on tropical saltwater fishes.

Blasiola, George C. 1976. Ectoparasitic Turbellaria. Marine Aquarist 7(2):76.

Blasiola, George C. 1976. A review of "white spot" Cryptocaryon irritans. Marine Aquarist 7(4):76.

Blasiola, George C. 1979. An introduction to the Platyhelminth parasites of marine fishes. FAMA 7/79.

Blasiola, George C. 1980. Brooklynella, a protozoan parasite of marine fishes. FAMA 5/80.

Blasiola, George C. 1981. Boil diseases of seahorses (Glugea). FAMA 6/81.

Blasiola, George C. 1990. A review of hole in the head disease of fish. FAMA 5/90.

Bower, Carol E. 1987. Update on Amyloodinium ocellatum. SeaScope, vol. 4 Fall/87.

Burgess, Peter. 1995. Marine whitespot disease; a fresh look at a salty problem. FAMA 1/95.

Gargas, Joe. 1993. External parasites of fish: Monogeneans and crustaceans. FAMA 6/93.

Gargas, Joe. 1995. Internal parasites of fish: cestodes, digeneans and nematodes. FAMA 2/95.

Goldstein, Robert J. 1973. Monogenea. Digenea. Marine Aquarist 4(1,2):73.

Goldstein, Robert J. 1974. Cryptocaryon vs. formalin. Marine Aquarist 5(1):74.

Goldstein, Robert J. 1982. Roundworms. TFH 9/82.

Goldstein, Robert J. 1990. Parasites in your aquarium; the best way to control parasites is to know more about them. AFM 2/90.

Herman, Roger Lee. 1973. Your fishes' health; Isopoda. TFH 3/73.

Herman, Roger Lee. 1974. Thorny-headed worms. TFH 7/74.

Herwig, Nelson. 1978. Treatment of Cryptocaryon- saltwater ich. TFH 2/78.

Herwig, Nelson. 1981. Disease prevention and control (on Cryptocaryon). FAMA 4/81.

Johnson, Erik L. 1994. Dewormers. TFH 8/94.

Johnson, Erik L. 1995. Your fishes health; eating for two (tapeworms). TFH 7/95.

Kabata, Z. 1970, edited by Stanislas F. Snieszko and Herbert R. Axelrod. Crustacean enemies of fishes. Book 1 of Diseases of Fishes. T.F.H. Publications, NJ.

Kent, Michael L. 1981. The life cycle and treatment of a turbellarian disease of marine fishes. FAMA 11/81.

Kloth, Thomas. 1980. White death (treating for Oodinium, Cryptocaryon). FAMA 5/80.

Michael, Scott. 1995. Attack of the ich. AFM 7/95.

Miller, Gary & Michelle Liu. 1990. Nonchemical control and eradication of Cryptocaryon irritans (spg manipulation and host removal). FAMA 3/90.

Rychlinski, Robert A. & Thomas L. Deardorff. 1982. Spirocamallanus: a potential fish health problem (a roundworm). FAMA 2/82.

Schettler, Jeff. 1995. New treatment of gill flukes in marine fish. FAMA 9/95.

Sprung, Julian. 1982. A little known environmental disease (hole in the head, later line erosion). FAMA 12/82.

Stansbury, Ed. 1984. Monogenetic trematodes. FAMA 11/84.

Straughan, Robert P.L. 1960. Salt water "ick" deadliest marine killer. TFH 10/60.

Violetta, Gary. 1980. A review of two epizootic marine protozoans: Oodinium ocellatum & Cryptocaryon irritans. FAMA 6/80.