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Robyn's Fish Health Page Two

Last Updated: 3/20/09

Diseases and Parasites Introduction
Fungus - fungus and egg fungus
Swim Bladder Disease

I wish I had the time to redo these health pages and add more information!

Also, check out my new page on general treatment for sick fish which includes a list of treatments when you do not have a clue, for bacteria, for fungus, and for parasites.

Diseases and Parasites Introduction

There is a plethora of information on fish diseases and parasites. Fish can have literally hundreds of species of bacteria, viruses, funguses, and/or parasites that live with them. In most cases, the fish can survive with them. Other times, the fish becomes sick and dies. Because this is a huge category in fish keeping, I do not have time to add more information here at this time. In the mean time, I refer you to the newsgroup called rec.aquaria.freshwater.misc and the following book: The Manual of Fish Health by Dr. Chris Andrews, et. al., Tetra Press, 1988. If there is one book a fish keeper should have, this is it!


Large parasites include anchor worm, fish lice, and fish leeches. Small parasites include those that cause ick (or ich) and velvet. Small parasites are often protozoans. Ick looks like white spots all over the body (not to be confused with tubercles on some breeding male fish such as the gills of male goldfish or the heads of male fathead minnows), and velvet looks like smaller yellow spots. Most medications against parasites are poisons. This means that sensitive fish like many catfish, discus, etc. may die from the medicine. In soft water especially, these medications are more deadly. Always try a new parasite killer first at half the recommended dose to see if the fish can take it. If they go crazy (jumping, flight behavior), it is killing them. Immediately do a 50% water change and add carbon to the filter. Even then, they could still die. I have lost more fish from adding medications than from any other cause.

I read that fish with flukes can be put into a 2% salt solution for up to an hour in an aquarium or container with no plants or scaleless/sensitive fish in order to get the flukes to fall off the fish. Whenever a salt or other dip is used, watch for signs of stress in the fish such as gasping for air, zipping around quickly, twirling, listing to the side, going upside down, etc. If that is seen, remove them immediately. An air stone will help keep dips/baths well oxygenated.


When some of my new fish developed ick from a new betta, I treated the tank with Aquari-Sol by Aquarium Pharmaceuticals as per directions, increased the temperature to 80 degrees F, and added more aquarium salt (about a tablespoon per 5 gallons). This worked for two outbreaks I had when new fish were added to my newly setup 20 gallon tank in 2001. See the health photo page for more information and a photo of the betta with ick and a few goldfish with ick.

Fish Lice and Anchor Worm:

A number of pond keepers have successfully treated their ponds for anchor worm or fish lice using Program which is a flea pill given to dogs. They used one pill for large dogs per 1000 gallons. Clout is often used to kill lice but may harm invertebrates. Fish lice are crustaceans that look like large alien beings attached to the fish. They can detach and swim to another fish. Anchor worm is a crustacean usually seen as a long white "string" coming off a fish, usually on the back or side. The "string" is actually the eggs of the female anchor worm. Both lice and anchor worm can be treated with dimilin which was hard to find. Program contains lufenuron which is very similar to dimilin and works as well. For more information on this study and results, see www.koivet.com/program.htm. I was contacted by Aquarium Pharmaceuticals which told me that they were registering a new product with actual dimilin to be used to treat fish for anchor worms and fish lice. "Pond Care Dimilin" came out in early 2003. One site that has information on it and sells it is pondliner.com. Most pond stores now sell it.

See this page for a photo of a goldfish with anchor worm.


Fish pox found in koi is a common virus. It creates white spots on the fish but is generally harmless. Lymphocystis is another virus found in many fish. It looks like cauliflower growths. It too is harmless.

In the Fall of 1999, a new virus in koi was made apparent as it wiped out some koi keepers' entire ponds. There seemed to be no way to treat it and many koi died. In 2000 and 2001, very few koi became ill and a new risky method of treatment was devised. The virus was named Viral Gill Disease. The virus allows the invasion of various bacteria that may be resistant to antibiotics in koi often treated with antibiotics. The virus is contagious even after a few hours in water with a sick fish. It does not seem to affect other species aside from various related carp. All new koi should be quarantined. For more information, check out the Mid-Atlantic Koi Club.


There are many gram-negative (-) and gram-positive bacteria (+). Each type of bacteria responds differently to various antibiotics so it may take a number of tries to find the antibiotic to treat the bacteria. Some common antibiotics are erythromycin (+), minocycline (-), tetracycline (+), penicillin, and sulfonamides (sodium sulfathiazole, sodium sulfamethazine, sodium sulfacetamide, etc.). Care must be taken when adding antibiotics to tanks as they also may kill the biological filter. Then, ammonia and/or nitrite could quickly build to deadly levels. Thus, the "medicine" kills the fish. In my tanks, penicillin killed off the good bacteria and my fish while erythromycin and minocycline did not have a harmful effect (they did kill off blue-green algae but did not seem to help with my TB outbreak as shown below).


Dropsy is a common internal bacterial infection where the fish is enlarged, and the scales stick out from the body. See here for a photo of a goldfish with severe dropsy and a link. If a fish suddenly becomes enlarged, it is usually dropsy. Fish tuberculosis or kidney malfunction/failure can result in a fish slowly become fat in which case the skin grows with the fish. Dropsy is also called pinecone disease because the fish look like pinecones. Most any fish can get dropsy. There are a few ways to treat a fish with dropsy. To help alleviate the pressure build up inside the fish, add salt. Regular salt, sodium chloride, may help some but Epsom salt (magnesium sulfate) works better for dropsy. If using regular salt, add a tablespoon per gallon for fish that can tolerate a lot of salt (goldfish, koi, etc.) and a tablespoon per five gallons for those that cannot (catfish, tanks with amphibians). See my salt page for more information. If using Epsom salt, add between 1/8 and one tablespoon per five gallons (internet sources do not agree at all!). In addition to the salts, antibiotics may have limited effect. At least one source says that metronidazole works - Bloat Photos and Treatment.

Fish Tuberculosis:

Tuberculosis is one bacteria that is hard to fight. I have lost a number of fish to this gram- positive bacteria. Oozing, cheesy open sores on a few goldfish, many danios, 2 white cloud mountain minnows, and a rosy red minnow eventually killed those fish during different years, in different tanks. Fish TB starts with little white balls in the body that may be seen in more "see-through" fish. As it grows, the fish appears to become obese with abnormal bulges, often just on one side. Eventually, the bacteria breaks the body wall and kills the fish. Larger fish, like goldfish, may survive open sores that look like infected red, cheesy boils for many months whereas all my small fish died as soon as they ruptured. Also, commonly small fish like danios and white clouds that were born normal developed kinked spines from TB as they aged and the TB set in. Tuberculosis apparently can be in a fish for years without any harm. If the fish is stressed in any way, the TB may become active. These carriers of TB who look perfectly healthy can spread it to the other fish even if they themselves are not yet or ever ill which is even possible. Older fish are prone to infections. Tuberculosis is sometimes killed using tetracyclines or sulfonamides. It is virtually incurable and causes cursing from normally polite aquarists. I failed to control an outbreak in 12/99 in my tanks (that were all exposed in the early 1990's) with minocycline (gram-negative anyway), erythromycin, or tetracycline. The first two were as pills in the water but the last was a medicated food. By 12/30/99, four goldfish had died. TB wiped out my goldfish tank. Such tanks should be bleached to kill the TB before being used for other fish.

One person says minocycline (which I mentioned, sold as Maracyn II by Mardel) is supposed to be effective against TB in some cases. He also mentions trying kanamycin. I am not sure which product that is in. As of today (7/04), I still lose a danio, white cloud, and rarely other fish to TB almost every few months. My pond goldfish have never shown signs of it except for a few possible instances (not sure) but my aquarium goldfish were killed off years ago (their tank now houses other types of fish).

Fish tuberculosis is a different species than human tuberculosis. It is said to be possible to get fish tuberculosis if you have open wounds in an aquarium so many people use gloves. I have never bothered with gloves, even when I have cuts and have yet to develop any tuberculosis-like signs. I do however wash my hands with soap and hot water thoroughly before putting them into any tank (to remove hand lotion, bad bacteria, etc. that might bother the fish) and after taking them out of any tank (to protect myself and my other animals and tanks). I wash between tanks as well to prevent spreading anything.

One hobbyist put together a small web site on fish tuberculosis. You can visit it here.

Fish Health Site to Visit:
A good web site with information on bacterial infections in fish including pseudomonas, aeromonas, columnaris, mouth 'fungus,' and tuberculosis can be found at this site. The site also includes information on viruses and protozoans. This site may no longer exist, if you know what has happened to it, please e-mail me.


Fungus is most common on fish eggs and on an injury site on a fish. Various medications that aquarium stores sell can be used to treat fungus on fish quite effectively. Often, fish die not from the fungus but the injury, parasite, or bacteria that created a site for the fungus to invade. Sometimes, the fish could easily recover from a cut except that the fungus invaded. Fungus is one of the easiest maladies to treat in fish when caught early. It may appear as a patch of fuzz on a fish, or the fish may look like it is covered in threads of fuzz if the case is advanced.

Egg Fungus:

Egg fungus is very common. As a preventative, keeping developing eggs in a dilute (medium blue) methylene blue solution with aeration for a few days (remove before hatching is expected as methylene blue may harm fry) seems to work. Most often, unfertilized or injured eggs are attacked by fungus. If the parent cares for the eggs like many cichlids and the fathead minnow, then the parent in charge will remove these eggs. Otherwise, you must do it. Methylene blue can aid in the process. Those eggs taking on the blue dye are compromised (infertile or have holes in them) and need to be removed. Without the dye, remove any eggs that are clouded (white) or obviously fungused. Tweezers work well for attached eggs while glass or plastic pipets work well for free (scattered) eggs. If the fungus gets out of control (when methylene blue is not used), all viable (usually clear with small eyes forming; some species like some cories may have colored eggs) eggs should be removed to a fresh setup with water of similar temperature, pH, etc. Fry should be removed to separate quarters as well because young fry can die from the egg fungus.

For more information on egg fungus, go to my breeding page.
For a photo with egg fungus, check out these rosy red minnow eggs where you can see there are just a few white, fungused eggs in the photo (for information on that spawning, check out this section).

Swim Bladder Disease

For now, check out this web site on swim bladder disease.

Here is a new Swim Bladder Help Site.

Also, see my Goldfish Health Page.

Pet Link Banner Exchange:

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