Sick Fish! What do I do?

By Kent Cannon

When you walk up to the tropical fish medication display at your local aquarium store, are you confused as to what to buy? What should I have in my medicine chest for that occasional disease that pops up, you might ask. How do I diagnose the disease that my fish seems to have? And what causes it? How am I supposed to know what I am supposed to buy when I can't even pronounce the name on the package? How do I know what symptoms point to what disease? Where do I find information that will help me answer some of these questions? If you've found yourself asking one or more of these questions, then you are not alone! Most of us are not used to treating disease�we rely on doctors to do just that for us! In most cases, finding a doctor to treat that sick fish is a rather pointless undertaking. By the time you get the fish to the doctor, the fish has undergone so much stress from netting and transporting that it is going to be a goner anyway! That leaves us back on page one. In this article I am going to try and help you answer some of those tough questions.

Where do I start? What should I have on hand, and where do I find the information to make an educated decision as to how to treat my fish?

  • The best place to begin is with a quarantine tank. This tank does not have to fit any special qualifications except that it needs to be large enough to handle the fish that you are placing in it. In the case of disease, it is better if the tank does not have gravel or a UGF (under gravel filter). That makes it easy to clean while it is being used, and easy to sanitize when the need for the quarantine is over. You will need an air stone or other means to cause surface turbulence to oxygenate the water (many treatments deplete the available oxygen) and a means of mechanical filtration (sponge filters work great). I have a ten-gallon tank for this purpose. I leave it out in the storage shed for just such an emergency. If you keep an eye open, you will be able to pick one up for as little as ten dollars at a yard sale or in the want ads.
  • The next thing that I would advise you to have on hand is a good fish keeping manual or book that has a disease section. Or better still, a book dedicated to diagnosing and treating tropical fish disease. Look at used bookstores and yard sales. You can also buy them through your local bookstore or aquarium store. There are also a number of places online that carry them. Here are some books to consider:
      • A to Z of Tropical Fish Diseases and Health Problems by Peter Burgess, Mary Bailey, and Adrian Excell.
      • Handbook of Fish Diseases by Dieter Untergasser
      • Fish Diseases: A Complete Introduction by Gottfried Schubert
  • I also keep on hand a few drugs and odds and ends with which to treat common diseases and problems. Remember that many drugs have a rather short shelf life, so do not keep on hand antibiotics. It is also a good idea to buy your drugs at a store that has a high turnover. I buy mine at one of the larger chain stores simply for that reason, while buying for my normal fish needs from my favorite aquarium store. I do keep on hand some aquarium salt (I'm gonna get flamed for that one), Quick Cure â (Malachite Green), Clout, Furanace â (Nifurpirinol), and/or Fungus Eliminator â by Jungle Products â . I also keep on hand some Epsom-salt, which you can find at your local grocery store. You will want to keep all of the drugs that you use for your fish in a place that is free from moisture and temperature extremes.

Now that you have your fish hospital and basic medications all set up, let's move on to understanding symptoms. How is your fish behaving? How does it look as opposed to normal? Is it hiding or is it sitting on the bottom? Is it free swimming or is it stationary with fins held tight to it's sides? Does it lean to one side, or does it have its head towards the surface or towards the bottom? Does it eat, and if it does eat does it spit out the food after a few moments? Is only one of your fish sick or are all of the fish in the tank sick? These are just a few of the questions that you will have to answer in order to treat your fish. Below are some of the common terms for symptoms used to treat almost all fish diseases:

  • Clamped fins - Fins held to the body, not swimming naturally.
  • Flashing - Scraping up against the decorations in the tank. Many fish do this occasionally, but when they do it continuously you need to pay attention.
  • Head standing - Swimming with the head down
  • Tail standing - Swimming with the tail down
  • Lethargy - Seems to have no energy stay in one spot, usually in a remote part of the tank
  • Listing � Leaning to one side or the other
  • Lack of appetite
  • Fin shredding/splitting - Fins look ragged and the spines within the fins can be exposed.
  • Scales sticking out - The scales on the fish stick out at a right angle to the fish's body.
  • Red Sores - Where are the sores? What do they look like? Are they red on the outside, or white on the outside and red on the inside?
  • White spots - Are there small white spots everywhere, or are there only patches of white that are in certain areas, like around the mouth?
  • Is the anus protruding and red? The belly of the fish should be in a smooth line (look at one of your healthy fish).

Many of these symptoms can be together or separate. You need to determine the sequence of the symptoms and which are involved with your particular fish. All of these things together will help you to properly diagnose what is happening to your fish so you can properly treat it. Every time you feed or look at your tank, pay attention to your fish! How do they normally act? Once you get good at picking out proper behavior, you will be better able to pick out fish that are healthy the next time you go to your LFS.

I am just going to touch on treatments in this article, although I do hope to do a follow-up at a later time. When you spot your fish acting strangely, the first thing that you want to do is check the water parameters. Check the ammonia, nitrite, and nitrate levels. Check the temperature and the pH. The most common cause of all problems in a fish tank is poor water conditions. Do a 20-30% water change and see if your fish start to behave in a normal manner. If you still have a problem, then you need to decide whether to isolate or not depending on the symptoms. If you catch many problems early you can save yourself a lot of worry!

Some of the common diseases are found in the next portion of this article. You can combine the symptoms given earlier with the descriptions of the following diseases to treat many of the maladies that are common to the aquarist.

  • Anchor Worm or Lernaea - Symptoms: An ulcer develops where the worm attaches; secondary infections may also occur around that point.
  • Bacterial Infections - As bacterial infections usually are due to poor water quality, it is imperative to first remove the primary cause. It is also important to remember that true primary bacterial infections are relatively rare, while most often problems are due to water quality or parasites.
  • Columnaris - A bacterial infection caused by Flavobacterium columnare . Fish with Columnaris usually have brown-to-yellowish-brown lesions or sores on their gills, mouth skin, and/or fins. Shallow skin lesions usually appear as patches that have lost their shine. Check for mouth and anal vent for sores. 
  • Costia - Costia is a parasite that nearly always causes little red hemorrhages, especially under the chin, but also along the back. If the red dots are under the scales, it is probably a bacterial infection.
  • Dropsy - Symptoms: Scales protruding at a 90° angle to the body; reddening of the vent area; and long, stringy faeces. Euthanasia may be in order.
  • Gyrodadctylus dactylogyus or Gill Flukes - Symptoms: Fish will consistently flash and rub as the infestation becomes more advanced, the fish will become lethargic
  • Hexamita or Hole in the Head disease - Common in all fish, but these protozoans are particularly deadly to cichlids. They infect the digestive tract and are associated with head and lateral line erosion. Symptoms: Fish will exhibit a marked decrease in vitality, darkened colors, lack of appetite, and slimy whitish-to-clear faeces.
  • Ich - Ich is primarily a cutaneous infection of freshwater fish caused by the protozoan parasite Ichthyophthirius multifilis . Ich most often causes the appearance of small white spots over the body and fins of fish. (Note that Ich can be present with many different appearances, and that other things besides Ich can cause small white spots on the body).
  • Malawi Bloat - Caused by feeding high protein diets to Rift Lake Cichlids. A majority of Rift Lake Cichlids are primarily vegetarians subsisting on mainly algae and other plant growth. Their intestines are extremely long in order to break down their common food (algae). When high protein foods such as bloodworms are fed in a frozen state and a dominant fish is able to grab large chunks of unthawed food, the food can sour in the fish's intestine and start a systemic biological infestation of the intestine. The first sign of this disease in lack of appetite (which in a Rift Lake Cichlid is readily apparent). This, coupled with lethargy and staying in its cave or a corner, is a sure sign of this terrible disease.
  • Nematode worms - Characterized by a thin, thread-like worm coming from the anus of the fish. The fish can become bloated, listless, and or skittish.
  • Oodinium or Velvet disease - Oodinium is a parasitic disease. Infestation causes a velvety texture all over the fish, or just in small patches.
  • Tuberculosis - The bacteria that cause fish TB is known as Mycobacteria marinum . Fish TB is not very contagious, and, as a result, if symptoms are noticed early it will not have an effect on the other fish in the aquarium. Symptoms include the following: loss of appetite, fish remains in seclusion and out of site, rapid breathing (respiration), eyes appear to be cloudy or "popping out," fish lies on its side near bottom of aquarium, stomach of fish appears to be sunken, white blotches on exterior, degraded and frayed fins.

As you can see, when you combine the symptoms with the various diseases and infestations, a pattern develops. As you become more adept at picking out the symptoms you can shortcut the disease and save yourself and your fish a lot of misery. It is too hard to touch on the many maladies that can affect your fish in one article. Hopefully, through the course of this article you have learned enough to start diagnosing the diseases that affect your fish.


First published in the newsletter of The Vancouver Aquatic Hobbyist Club