Fish diseases: A Primer
I got a PM recently from a user who wanted to know if his sister's fish had Ich. I told him yes, and what to do about it. And that PM got me thinking about Ich and other diseases that affect freshwater and marine fishes. So, I thought it time to write up a post about the most common fish diseases you're likely to run into, and how to cure a fish infected by them.
Surprisingly, several of the same diseases are both found in freshwater and marine fish, and the life cycle of the parasites are very similar. For example, both marine and freshwater fish contract Ich, and though the protozoa that causes the disease is different, with the freshwater parasite Ichthyophthirius multifilius and the marine Cryptocaryon irritans, the symptoms of the disease are exactly the same, as are the reproductive strategies.
In this post I'll list several diseases as to what they are, how they operate, and how to cure them. Correct diagnosis is essential to a cure, so I encourage you to make yourself familiar with what the parasites look like. Google images is handy in that respect.
I should say that this primer shouldn't make you afraid that around every corner there's a parasite there to kill your fish; on the contrary, it's unlikely you'll run into the majority of them, if you're a conscientious aquarium keeper. So, I wrote this primer on what to do if you ever run into one of them.
Now, on to the diseases.
Ich (Ichthyophthirius multifilius) is perhaps the most common disease that plagues freshwater fishes, whether in the aquarium or in commercial fish farming. In this post I'll tell you what it is, how to prevent it, and how to cure it.
Ich is simply a protozoan, that is, a tiny unicellular organism. Though it's among the largest protozoa that infects freshwater fishes, it is so tiny you'd need a microscope capable of 100X magnification to see it, similar to what you'd need to see things like amoebae or paramecium, clearly. The adult Ich protozoan is round to slightly oval, and covered with thousands of cilia (hair-like threads used for propulsion). Its nucleus is shaped roughly like a horseshoe, making the parasite easy to pick out through a microscope. The much smaller motile protozoans are teardrop-shaped, and it takes a very practiced eye and high magnification to identify them. The natural life cycle of Ich is a week to 10 days, depending on the temperature.
And it's a killer. Ich is an obligate parasite, that is, it has to have a live fish to during it's life cycle to perpetuate its species. When a fish is compromised by a chill (rapid lowering of tank temperature) or stress, or an infected fish is introduced, the parasite can penetrate a fish's protective slime coat, and burrow into the fish's epidermal layer where it encysts itself and is referred to at that stage as a trophont (a reproductive body). Thus encysted, the parasite grows up to 1 mm in size by feeding on fish cells. The parasite divides into many hundreds of copies of itself, the cyst drops off the fish within a week, anchors to the substrate, and in a day or so it bursts, and the tear-drop shaped copies surge out looking for a fish to encyst upon. Without fish, the motile parasites die within 48 hours at 80 degrees.
The motile parasites can encyst themselves on the fish they came from, which is why Ich can spread so rapidly on a fish. A fish literally covered by cysts is quite usually doomed. Unchecked, Ich can easily kill every fish in a tank. It is one of the few fish parasites that is 100 percent fatal if not promptly addressed.
Thankfully, when identified early enough, when there are just a very few spots of Ich, the prognosis is excellent.
Hundreds if not thousands of times I've recommended founding a quarantine/hospital tank to prevent introducing disease into your main tank. The benefit vies a vise Ich and other diseases is quarantine tanks are most usually small, like a 10-gallon tank. Thus, an observant person can pick out a fish with an Ich spot or two quite easily, and take prompt steps to eliminate the disease.
The most common excuse not to have a quarantine tank is financial, but replacing dead fish routinely will cost you more than the money for a 10-gallon quarantine aquarium set-up in a short time.
There are several methods of eliminating the parasite, and some are more effective and safe then others. The best cures are those that stress the host fish as little as possible.
The most popular cure is marine salt and heat. The former, because most fish can tolerate the salt, the latter, to speed up the life cycle of the parasite. Average temperature for the process is 82 degrees, and salt is added at a prescribed amount for the types of fish you keep. It's best to use real sea salt in this process.
It works because the motile parasites, which are those that burst out of those cysts, do not adapt to the osmotic change in the water due to the salt, making it difficult for the motile parasites to move, killing some, and more difficult for them to find a host fish in time. As you remember, if the motile parasites can't find a host fish in 48 hours, they'll die.
I say more difficult to move because at the size protozoans are, water is thick like pancake syrup. Protozoans are mostly water. They have a nucleus where the DNA (Deoxyribonucleic acid) and some of the RNA (Ribonucleic acid) are, with those making the blueprint of what the creature is. The nucleus is surrounded by cytoplasm, which is thick enough to maintain just enough pressure against the water pressure for the protozoan to maintain it's shape. In that cytoplasm there are a few to several small ovals of most of the RNA in communication with the DNA and RNA in the nucleus.
When salt is added, it makes life difficult for the motile protozoans. I. multifilius is a freshwater creature. Protozoans very much are what they are, and thus are such simple organisms with just a single cell they can't adapt to change like higher organisms can. You and I can walk out of a warm house to say, a 30 degree day. People can do it easily; walk between changing temperatures and air pressure. Fighter pilots go through maneuverers of many times the force of gravity. Higher animals can easily adapt to change. Simple organisms can not, at least not in any kind of hurry.
The heat is reputed to speed up the life cycle (encyst to motile protozoan). The motile protozoans must find a fish at 80 degrees within two days. The thought is that high heat - say in the low to mid-80's, would speed up the life cycle so the salt can take care of the motile protozoans before they have time to infect another fish.
The downside of this process is it's very, very hard on small, and scaless, fish. Those that developed in soft, acidic waters like the majority of tetras and Corydoras catfish, also don't do well in the long period (usually a week to 10 days) of salt and heat. Also, large partial water changes are needed to remove the salt from the aquarium system.
The astute among you have picked up that if the motile protozoans can't find a fish to encyst upon within two days, it dies. And that, my friends, is why I recommend a quarantine tank.
A quarantine tank is designed to give new fish or fishes the once-over, and also to get them eating. Personally, I quarantine every fish at least a month. A fish that comes in with a spot or two of Ich is isolated, treated, then later returned to quarantine. In over 30 years no disease of any kind has gotten into my show aquariums because I use quarantine.
Another method of curing Ich, and the one I favor, is a marine dip.
A marine dip is a container of marine water of the same temperature as the tank the fish came from. When I say marine water, it's tank water that has commercial marine salts added to make it like sea water, that is, 1.026 specific gravity at 77 degrees. I use a clear glass beaker for the container, and run an air stone during the process for the fish's benefit and to help evenly mix the salt. You can use whatever container you like, as long as you can see the fish clearly, and you'll need a refractometer or hydrometer to measure the salinity as you add the salt..
An infected fish is identified, and removed to another container of quarantined aquarium water, since it does healthy fish no good to be treated for a disease they don't have.
The affected fish is then placed in the container of salt water, and removed when it shows distress. Different species of fish take different amounts of time before they show distress. Larger Cichlid species can take it up to 10 or 15 minutes fairly easily, small tetras and similar well under five. When the fish shows distress (rapid breathing is a sign) it is removed and returned to isolation.
It works because the fish can stand the osmotic change from fresh to marine water for a short time. The encysted protozoans can not, and die almost immediately; within seconds. Some recommend following the dip with a formalin* bath, but I've not found it necessary with freshwater Ich.
The cysts darken and fall of the fish within a day if there are just a few spots, perhaps two if there is a heavier infestation. The marine water does cause the fish to produce more slime coat, and is perfectly healthy and ready to be returned to quarantine usually within a week.
It is vitally important to maintain the same temperatures in this process, as you want to stress the affected fish as little as possible. All my tanks run at 77 degrees, so all my quarantine tanks are the same.
The downside of the marine dip is you have to sit and watch the fish very closely to detect distress. Also, you have to purchase marine salt, refractometer, airstone and an air pump, and have a container for the process, and another to isolate the fish after it.
Last edited by Fishalicious; 04-05-2009 at 08:08 PM.
Yet another way to cure Ich is by commercial medication. Several of them contain Copper Sulfate, which will give you more problems than you started with. Copper at the levels of the medications will make it impossible for invertebrates to live in your tank, including all the beneficial ones like copepods and nematode worms that help make aquarium keeping possible, because they process nutrients before they can decay. Select Ich medications very carefully before purchase, and know exactly what's in them.
Some medications work better than others. I won't mention brand names, but check the labels and seek out impartial reviews before purchase.
Analogous to it's fresh water cousin in its ability to spread and kill is marine Ich; Cryptocaryon irritans.
Perhaps the most common disease that appears in marine tanks, Cryptocaryon is again an obligate parasite, needing a live fish to complete its life cycle. Though the effects of the disease are very similar, the reproductive strategy is somewhat different than it's freshwater cousin, as the tomonts can stay dormant in the substrate for quite some time waiting for adverse water conditions, while the freshwater version's tomonts burst within a week after dropping into the substrate regardless of water quality.
The motile protozoan encysts on the fish, feeding on it while dividing into hundreds of copies of itself, before detaching within a week and falling into the substrate. Once there, the parasite moves around the substrate, encysting itself in a chosen spot becoming what is called a tomont (the reproductive body). The tomont can lay dormant for months, waiting for conditions to vary in its favor. When water quality starts to fall, the tomont bursts, and the copies surge out seeking fish, and the cycle resumes. That delay between tomont and reproduction is responsible for recurring cases of Marine Ich, usually in larger and larger numbers of parasites. Some fish are more susceptible to the disease than others. Tangs are infamous for their ability to be infected by Marine Ich. Marine Eels and cartilaginous fish are virtually immune to it. Most other species of marine fish fall in the middle of susceptibility.
Symptoms include flashing against objects, clamped fins, lack of appetite and the telltale white spots the size of a grain of salt on the body of the fish. Cryptocaryon can attack the gills first but spots are soon found on the fish, making diagnosis easy.
Only a compromise in tank conditions such as temperature fluctuation, levels of Ammonia and Nitrite typical of newer aquariums, high Nitrate, or shoddy maintenance, can activate the tomonts and bring on the disease. Cryptocaryon is incredibly rare in nature, and fish with it rarely if ever die from the infection because of the stability of the reef environment. Only the closed conditions of the home aquarium make it the ideal environment for the parasite.
Affected fish or fishes MUST be removed from their tank for treatment, as all potential cures are fatal to invertebrates, despite manufacturers' claims. Also, to make sure the parasite is gone from your aquarium system, the tank should be vacant of fish for at least two months, better 90 days. Without fish, the motile parasites die within two days, but as tomonts can lay dormant for some time, the extended period fishless is necessary to make sure the parasites are gone for good. Fish-only tanks can have the temperature raised up to 90 degrees to hurry the destruction of the motile parasites, but no fish or inverts can be present.
Cures are many, and some are far more effective than others. The quicker the infection is detected the better the chance of a rapid cure.
The one I favor is a formalin* dip.
A container is prepared with tank water and set at no more than 77 degrees. A rapidly bubbling airstone is added, as formalin* can make it more difficult for the fish to breath. The dosage of formalin* listed by the manufacturer is added, and the affected fish is place in the container for up to an hour, removed sooner if the fish shows distress. The process is repeated daily for a week to make sure all the trophonts on the fish are dead. They will turn dark brown to black and fall of the fish when deceased.
Medications containing Copper Sulfate are commonly used to combat Marine Ich, but is only affective on the free-swimming version of the parasite, as the imbedded trophonts are immune to the Copper Sulfate. As the motile parasites are released just after daylight (Colorni & Burgess, 1997), the very early morning would be the time to treat fish with a Copper Sulfate medication. Copper is also absorbed by any calcareous media, which will render it useless, and Copper is fatal to all invertebrates.
In my opinion treating Marine Ich with medications containing Copper is too dangerous, as it's easy to over or under dose, with the former fatal and the latter useless. It can also damage the fish internally, particularly the kidneys and liver, and can make the fish less resistant to other diseases.
Another method is hypo-salinity, that is, less than the marine water concentration of salts. I haven't tried this method but have heard excellent reports on it.
An infected fish is acclimatized to 1.010 salinity and isolated for two weeks with the temperature between 78-80 degrees. Most fish can easily adapt to lower salinity, but some can't for the extended period, and should be removed if distress is detected. The cure works because the parasite can't adapt to the lower salinity, and it kills the infectious motile versions outright. The two-week period is necessary to make sure the parasite is completely gone. Also, the lower salinity means the fish's body doesn't have to work as hard to void the salt, meaning they are less stressed by it.
Returning the fish to normal salinity should be done very, very slowly - .01 to .02 every other day. The process must only be done in isolation, as it will kill most invertebrates, including all the beneficial ones in substrates and live rock.
Though I haven't used this method, I would think it the safest cure.
Of course, quarantining all new arrivals at least a month is essential in keeping the parasite out of your show tank and will keep you from having to leave it fishless for months. If you never want to experience the reoccurring cases of Cryptocaryon in your main tank quarantine is the only way. All medication should be done in a separate container of tank water to avoid nuking the biofilter in the quarantine tank.
Another common disease among freshwater and marine fish is Piscinoodinium pillulare in Europe, P. limneticum in North and South America (FW) and Amyloodinium ocellatum (Marine), commonly known as Velvet, or Gold-Dust Disease.
In freshwater, Piscinoodinium has a life cycle similar to Ich, since it needs a live fish to complete it's life cycle. A much smaller single-celled organism, Piscinoodinium is a dinoflagellate, that is, it has a whip like 'tail' that it uses for propulsion. It also uses that tail to help burrow into a fish's slime coat, where it feeds by eating the fish's fluids. It, too, encysts itself, constructing a tiny shell. To the human eye the cysts appear to be gold to rusty-colored dust.
Velvet is an insidious disease, and a lot tougher than Ich to detect and cure. It commonly attacks the inside of the gills first because of the soft tissue within, which irritates the fish, so if you see fish flashing, that is the fish quickly rubbing against ornaments or gravel, or seeming to gasp, you could have Piscinoodinium on your hands. The habit of attacking the inside of the gills first means initial diagnosis is difficult. By the time you see the dust on the fish itself the infestation is far along.
Its protozoan is also a lot faster than Ich, and a Velvet infestation can spread like wildfire. The tiny cysts drop and within a week, burst, and the millions of flagellate-equipped protozoans zoom around looking for a fish to infest. It also has chloroplasts, which means it can metabolize light to supplement their diet. Piscinoodinium anchors itself in its chosen spot, meaning a root-like extension is pushed into the outer flesh of the fish.
If you see your fish flashing, going off food, losing color, or gasping, turn out the tank and room lights and shine a flashlight on the affected fish, aiming toward the gills. This is best done at night, as the fish will be more calm. The beam of the flashlight will cause Piscinoodinium cysts to shine a bit. If the gills are swollen as well, it's a sure sign that you have a Piscinoodinium infestation. Vigilant attention to your fish is essential, as Piscinoodinium can overwhelm and kill a fish within three days.
As above, identifying a fish with Velvet is a great deal easier in quarantine.
Last edited by Fishalicious; 04-05-2009 at 08:10 PM.
Darkness is the number one thing to do first when a Piscinoodinium infection is observed, meaning no aquarium or room lights on, and windows tightly shuttered. Pitch darkness stresses the protozoan a good deal, and when it uses up its starch reserves (within a day), it is very vulnerable to medication. In freshwater, what has been successful for me is equal amounts of formalin and Malachite Green. The formalin is available over the counter and is commonly 37 percent formaldehyde and the rest water, and Malachite Green is available in better pet stores and online. The affected fish is placed in a two-thirds full container of tank water, and a rapidly bubbling airstone is used. Equal amounts of the recommended dose of Malachite Green and formalin are warmed to the tank temperature and added to the container to fill it. The affected fish is placed in the container for no more than five minutes, then removed to isolation, and observed closely for the next several days, checking daily with darkness and flashlight to make sure the parasite is gone. If not, the procedure is repeated daily until it is.
Since the parasites are much shallower on the fish than Ich is, the osmotic change in the water with the medications kills them nearly instantly, though the fish may be a gasper the rest of its life due to the damage the parasite does to the gill tissue.
There are commercial medications that are purported to eliminate both Ich and Velvet which I wouldn't hesitate to use if the Piscinoodinium has spread to other fishes. As always, follow the instructions on the packages to the letter.
Needless to say the process should ONLY be done in a quarantine tank.
In marine, Amyloodinium is again a much faster species and it's life cycle is a good deal faster than marine Ich (Cryptocaryon irritans), meaning it takes less time to spread and kill. First, the flagellate-equipped dinospore, which is the mature motile creature, finds a fish, and puts in an anchor, feeds on the fish, constructs a shell around itself, and becomes a trophont (the reproductive body). When mature, the trophont detaches and falls off, and more than 250 young dinosphores soon erupt from the detached trophont and searches for a fish to infect. And, as even a small infection has many thousands of trophonts, you can see just how quickly the parasite can spread and kill. Amyloodinium can wipe out a tank's population in a matter of three days. The dinosphores must find a fish to infect within a week. Some will die within 48 hours, some will last the whole seven days before dyeing.
Identifying the infection early is crucial. Fish acting in any way abnormally, like losing color and appetite, and perhaps also flashing, should be very promptly checked for the parasites, which again attack the gills and region around it, with pitch darkness and flashlight. Unlike the freshwater version, the marine parasite lacks chloroplasts, so extended periods of darkness affect it not a bit.
In marine, a cure is more problematic. The affected fish or fishes MUST be isolated and quarantined, if one doesn't quarantine new arrivals. The standard method is a freshwater dip with Methylene Blue added. However, the freshwater MUST be the EXACT same hardness, pH and temperature of the tank the fish comes from, since marine fish are far less adaptable to changes in pH and hardness freshwater fish are. Running an airstone is helpful, as it tends to mix the Methylene Blue with the water more effectively, and the airstone helps with gas exchange, keeping the Oxygen level high for the fish.
The container should have just enough marine salt added for 1.001 specific gravity, and Methylene Blue added at double strength, based on the amount of water in the container. The affected fish is placed in the dip, and removed promptly at three minutes. The cysts burst and the protozoans die virtually upon contact with the Methylene Blue-tinted water, since, like the freshwater species, the trophonts aren't buried deeply, thus are very susceptible to changes in osmotic pressure.
The fish is returned to isolation, and observed closely. The same darkness and flashlight can help you check if the fish is clear of the parasites. If not, the dip is repeated the next day, then every day until you are completely sure no infection remains.
The affected fish should spend at least three weeks alone in quarantine to recover and heal before return to its tank. If the infection is caught early enough, the prognosis is excellent, so if you see a marine fish flash, go off food or any of the above symptoms, check with darkness and flashlight immediately on that and every other fish in the tank.
Salt and Reef tanks that are kept in perfect Natural Sea Water (NSW) conditions and have regular maintenance make it relatively unlikely you'll run into Amyloodinium. Of course, the wise keeper quarantines new arrivals for at least a month to prevent introducing disease to precious marine fish. And as fast as Amyloodinium kills, prevention by quarantine is more than essential.
Also, those aquariums equipped with a UV sterilizer rarely if every run unto external disease protozoa like Velvet unless they add a fish infected by it to their tank.
A common disease found primarily among surgeon fish, though it can infect other marine fish, is the so-called Black Spot, which is caused by a species of sub-microscopic flatworms of the Genus Paravortex, a Genus full of parasitic flatworm species that infect several kinds of invertebrates as well as fish. Though Black Spot is a common parasite, it is much easier to eliminate than the more pernicious diseases of salt-water fishes if caught early. Nevertheless, given its ability to procreate in massive numbers, any Black Spot detected should be addressed by the fish keeper immediately.
The worms feed among the detritus in the substrate for some months before they are mature enough to seek out a fish to start their life cycle. The worms themselves are transparent. It's only when they start feeding on the fish do they turn black and can be detected, and they appear roughly the size of a grain of salt. The worms themselves can move, grazing on the fluids of the fish, which is why Black Spot can seem to move day to day.
After feeding on the fish for a week, the worm drops of back into the substrate, and within four days ruptures, sending out hundreds of its kind, where they feed on detritus until mature and the cycle starts over again, this time in much larger numbers of worms infecting fish.
Continued cycles of Paravortex can literally cover a fish to it's cost, so it is essential to treat a fish when a Black Spot is discovered as quickly as possible. The parasite can proliferate to the point the fish can become lethargic, go off feed and soon die. In large numbers, the eradication of the worms can open the fish to bacterial or fungal infections.
It is easy to pick up the spots on light-colored fish, so the thousands of yellow tangs in the hobby make it simple to see the disease on them. On dark-colored fish it is more challenging, so the infection usually progressives further until they are flashing off the substrate and objects to try and dislodge the parasites. A dark tank and dark room, and a bright halogen flashlight, can help you see the black spots on the affected darker-colored fish.
Treatment is relatively simple; a freshwater dip followed by a formalin* bath, at the dosage recommended on the package. Also, an air stone must be used in the treatment container, as formalin* can limit the amount of Oxygen the treatment water can hold. The freshwater must be exactly the same pH, temperature, hardness and chemical balance of the tank the fish comes from. Enough marine salt should used to raise the specific gravity to 1.001, the correct dosage of formalin is added, and the affected fish is placed into the container for no more than three minutes, then removed to quarantine.
This works because the change in osmotic pressure kills the worms almost instantly, since they can't adapt to the slightly salty freshwater, and the formalin makes sure any motile creatures are killed. The process needs to be repeated twice a week for two weeks to be sure of killing the parasite due to its extended reproduction. Of course, treatment must be done in a separate container, and the affected fish or fishes must be quarantined for at least four weeks. Partial water changes and vacuuming the quarantine tank daily will prevent any worms that survived the process are vacuumed up and disposed of before they drop off the fish and rupture, sending out copies.
A stressful process, but one that always works. Of course, the fewer the number of black spots the easier it is to eradicate. Remove all fish from the tank for at least a month to make sure any offspring of the worms are gone.
Clean tanks and top-shelf maintenance make it unlikely you'll run into Black Spot, and marine aquariums equipped with a UV sterilizer rarely run into motile diseases. Quarantine is all but essential in the Marine and Reef hobbies, since by no means do you want Black Spot or any other disease added to your show tank. Also, Neon Gobies and others of its Genus can pick the parasites right off a fish, so it's always handy to have a group of these fish on hand to destroy parasites before they can spread.
Last edited by Fishalicious; 04-05-2009 at 08:12 PM.
Far more common than it used to be in freshwater tanks, is Flexibacter columnaris, commonly called columnaris in the hobby.
Errantly described as fungus on the internet and in some books, Flexibacter is a bacteria. The colonies of bacteria form into microscopic columns on the surface of an affected fish, thus earning the species, and common, name. These columns, especially around the mouth of an affected fish, can be thread-like, causing mistaken identification of the bacteria as a fungus, meaning treatments for fungus have no affect on the bacteria. Remember, fungus only appears on dead cells, like around an injury. If there is no injury, it is highly likely that you have columnaris on your hands
The protozoan that causes the disease looks rather like an Elm leaf under the microscope. The slipper-shaped microbe has cilia on it's ventral side for locomotion, and has an oval nucleus and two RNA vacuoles. F. columnaris is a borderline parasite, that is, it isn't essential for it to parasitize a fish for its to complete its life cycle, but at the natural, low levels they merely board on the fish and take very little, if any, fare, or be dormant in your substrate. There are possibly columnaris bacteria on your fish right now, part of the tens of thousands of species of bacteria on the slime coat of your fish. Healthy fish in healthy, stable tanks are basically immune to columnaris. It may be in your tank, but can stay dormant for years.
Symptoms are grayish to white lesions on the fish's body or fins. The lesions can be rimmed in red from the blood of the fish, and the lesions can turn completely red as the disease advances. The fish can appear covered in gray slime. Fins can degenerate to nothing. The fish can appear to gasp at the tank surface, flash off object, have clamped fins or be quite lethargic and go off food. Columnaris can be either external or internal, the latter with few visible signs. If untreated, a infected fish will die.
Hard, alkaline water and temperatures over 77 degrees make it ideal for the bacteria, and they can flourish to your aquarium fishes' ruin in such waters. Columnaris is responsible for the 'shimmying' of live-bearers, especially common in mollies. Soft, acidic tanks kept 77 degrees or under and properly maintained rarely run into the parasite.
The cause of the disease is exclusively that of the fish keeper. The bacteria is continually in most aquariums. It is only when water quality is poor, there are wide swings in pH, temperature or hardness, bullying of tankmates, crowding, high nitrate, low dissolved Oxygen and other stress factors make the bacteria surge in massive numbers and can kill fish. There are several strains of columnaris cropping up in the hobby, primarily arriving in the US from fish farm bred in Asia, some so virulent a fish can die in less than a day. It is beyond important to quarantine all new arrivals at least two weeks to prevent bringing one of those deadly strains into your show tank. Columnaris can easily kill every fish in your tank in days.
The cure involves improving conditions with twice daily partial water changes and vacuuming the substrate. Slowly lower the aquarium temperature to under 77 to slow the advance of the disease. Remove affected fish and place them in isolation. If the infection is external, antibacterial medications, particularly those with acriflavine, erythromycin, nitrofurazone or tetracycline in them can kill the bacteria on the fish. Follow dosage recommendations to the letter, and continue treatment for two weeks. Medicated foods containing oxytetracycline can help if the fish is still eating, and is the only way to eliminate internal infections; such food should be fed for at least two weeks, regardless if the fish seems to be healthy sooner. Light levels have no affect on the bacteria, since it lacks chloroplasts.
Needless to say treatment MUST be done in isolation, as anti-bacterial medications will kill the beneficial bacteria as well as those you are trying to eliminate, causing a giant ammonia surge that will kill all the fish in your tank. A treated fish should be in the most pristine, cycled tank quarantine tank possible and a rapidly bubbling air stone should be used to keep Oxygen levels high after the affected fish are treated. Commercial substances designed to improve the fish's slime coat should be added to help the fish heal from the ordeal, and help prevent infections of other diseases due to the compromised fish.
Well-maintained, thoroughly stable and clean aquariums rarely if ever run in to a columnaris attack, and wise keepers quarantine all new arrivals. The higher the water quality and stable the tank the less likely you'll have to deal with columnaris.
The marine counterpart of columnaris is Brooklynella hostilis, the so-called clown fish disease, though it can affect most aquarium-kept marine fish, and is one of the most dreaded diseases a marine keeper can experience in their tank.
The culprit is a ciliated protozoan and gets into your tank when you add a fish to your aquarium possessing it, which makes it extremely vital to quarantine all new arrivals a month. The symptoms of the disease is very similar to the freshwater version, but if anything, Brooklynella is if anything more resistant to cure and so rapidly pernicious a fish can be overwhelmed in days.
A fish affected by the disease can have paling in ever wider areas as the parasite multiplies as it feeds on the fish. In latter stages, the areas can turn gray and the fish's flesh can slough off. A Brooklynella infection weakens the fish and is always fatal if not promptly addressed. Sadly, poor water quality either in your tank, or along the fish's journey from the wild to your tank, causes the onset of the disease. Quarantine to keep it out of your main aquarium and top-shelf conditions within it will do leagues in prevented the spread of Brooklynella.
A cure is four-fold.
First, a freshwater dip is used. The fish is isolated in freshwater that has just enough marine salt in it for 1.001 specific gravity for up to 15 minutes, less if the fish shows distress. The freshwater must be the same temperature, pH and hardness of the tank the fish came from.
This if followed by a 15-minute bath in tank water with the recommended dose of formalin* in it the next day.
After the formalin* bath, the fish is returned to quarantine and an antibiotic medication (Acriflavine) added to the water at the recommended dose for two weeks, and a UV sterilizer is attached to take care of any motile parasites that can attack a weakened fish. The antibiotic is removed with fresh carbon in an external filter (no other media) and 50 percent daily water changes after the two weeks.
Fourth is keeping your tank in perfect shape, with regular partial water changes and the prompt removal of any debris.
If the fish is acting and eating normally after the above procedure it can be returned to the show tank at the end of a month.
Common on aquarium fish is Ichthyobodo necatrix, commonly called Costia.
In normal levels Ichthyobodo isn't dangerous, and is part of the soup of micro-organisms on the fish. The fish's natural defenses keep it in check. Only when water quality falls due to negligence of the fish keeper, the protozoan will explode with growth and can proliferate to the point it can kill the fish affected with it if not promptly addressed.
It can attack the gills, causing rapid breathing and perhaps gasping at the water surface. The fish can flash and rub itself on objects, the skin can appear cloudy and excess slime coat can be produced. In the latter stages the fins can be clamped and the fish is lethargic and can isolate itself or hover above on the substrate. At that point, it is unlikely the fish can be saved, but you can certainly try.
Thankfully, Costia is easily cured if caught early, and the prognosis is excellent. An infected fish is isolated in tank water, a rapidly bubbling airstone is used, and a commercial antibiotic medication is added per manufacturers direction. The fish is left in isolation for an hour, the removed to quarantine for at least two weeks. It is helpful to add a substance purported to restore a fish's slime (per directions) to help the fish recover.
Usually a single treatment is all it takes, but if the Ichthyobodo seems to make a comeback (doubtful if excellent water conditions are maintained), a 15-minute bath in tank water with Malachite Green and formalin* added will finish it off.
Whole tank treatments are ill advised, but long term prescribed levels of marine salt with chloramine-T added to help depress the bacteria can be used until the fish improve. I wouldn't recommend whole tank treatments, as healthy fish can be stressed by it, and open themselves to other diseases. Also, a mild antibiotic like chloramine-T will play havoc with your Nitrifying bacteria, though using it with the salt is very effective in helping the fish recover. Remember, a stable, cycled, established tank with regular maintenance will make it unlikely you'll ever have to deal with a Ichthyobodo plague.
Last edited by Fishalicious; 04-05-2009 at 08:15 PM.
Not uncommon on fish is Trichodina, another sub-microscopic protist. Unlike most diseases, [i]Trichodina isn't by nature a parasite. It merely uses a fish for locomotion, and doesn't feed on the fish at all.
A circular creature, Trichodina attaches to the fish with a sucking disk (interlocking "teeth" forming the sucker) on it's ventral side. There is stays, using chloroplasts to feed itself. It's only poor water quality and sub-standard conditions that overwhelms the fish's control of it, can Trichodina become dangerous. The population explodes, and the millions of sucking disks irritate the fish, and they flash like mad attempting to dislodge them. The disks can cause tissue damage, and reddening can be in some areas. The damage the disks can do can open the fish to all sorts of infections.
Cures are few, but can be can be effective
What I've used is a an hour-long bath with tank water dosed with Potassium Permanganate.
A container equipped with a rapidly bubbling air stone is used, the affected fish or fishes are added, and the recommended dose of Potassium Permanganate is added. Usually only one treatment is required, but if by chance it isn't, it is repeated the next day.
After treatment, the fish are quarantined for two weeks, and a commercial slime coat restorer is used. Water quality, both in the quarantine and the main tank, must be top-shelf to avoid a repeat of the episode. Also, the damage the Trichodina can do can open the fish to other bacterial infections, so keep a close eye on the fish in quarantine and take steps if necessary with an antibiotic medication. Of course, this should only be done in an isolated container to avoid killing beneficial bacteria in your sponge filter.
Other treatments can be salt, but it's difficult to know how much salt is needed to kill Trichodina, and salt treatment is dangerous to some types of fish.
Baths in tank water with Malachite Green and formalin* added can work, and chloramine-T dosages is reported to be effective. In the latter two methods a rapidly bubbling airstone is mandated to keep Oxygen high for the fish, and of course the treatment water should be the same temperature, pH and hardness of the tank the fish comes from.
Heximita is another ciliated protozoan that uses a fish for its transport. It's only when a fish's health is compromised by water quality and/or poor diet does it become dangerous.
Mainly seen in mid to large-sized Cichlids, though it can attack lager gorami species as well, poor diet or poor water quality can both depress the fish's immune system, allowing Heximita to gain the upper hand and have a massive surge in population. Small pinholes can appear on the fish's forehead that get larger and larger, becoming pits, or holes if you will. If untreated, a Heximita attack can easily kill a fish.
A prompt improvement in water quality and a more varied high-quality diet is all that is necessary to reverse the effects of Heximita and allow the fish to heal. However, in a more advanced stage, a commercial antibiotic may be necessary to eliminate the infection. Needless to say, any antibiotic should only be used in another container of tank water, never in a main tank, to avoid destroying your bio bed of beneficial bacteria.
More common than once thought, and unfortunately incurable, is [i]Pleistophora hyphessobryconis[i], the so-called Neon Tetra Disease, our last disease.
This disease, a freshwater parasitic internal fungus, was first identified in Neon Tetras (Paracheirodon innesi), thus the common name. It can infect all kinds of small schooling fish, and Cichlids such as Angelfish, but for some reason, Cardinal Tetras (P. axelrodi) seem highly resistant to it and rarely fall ill.
There are several species of Pleistophora in both freshwater and marine environments and all are parasitic. P. hyphessobryconis is by far the most common species that attacks aquarium fishes, and the marine version is exceedingly rare in the hobby.
The only way for a fish to become infected with Pleistophora is for them to eat something containing the fungus, like a dead fish, or biting another fish with the disease. Live tubifex worms harvested from filth, like that from a factory runoff, can have the fungus within them, though research indicates it is most prevalent in the Northeast US. Once in the fish's intestinal tract, the fungus dig through the walls, and encysts itself in the fish's muscles. Once there, the muscles start to die, causing the paling due to loss of color in the region. Lumps and bumps can appear on the body of the unfortunate fish. As the heart is also a muscle, the disease can kill in days.
Sorrily, the only course of action when this disease is identified is euthanasia. Freezing the affected fish is the most humane way.
As there is no cure, the best course is prevention. Remove all dead fish as quickly as you can. If you wish to feed live Tubifex, culture them yourself and get your start-up from a reliable supply house, or get frozen or freeze-dried examples. Like all diseases, prevention is your best defense. Buy your fish from clean, well-maintained shops. Quarantine all new arrivals at least two weeks. And keep your tank clean and stable, and do weekly partial water changes and regular vacuuming without fail.
These are all the diseases I've dealt with over 35 years in the hobby. Aside from freshwater Ich, most diseases are relatively rare and some exceedingly so, but I believe you should know about them and what to do if you run into any of them, because forewarned is forearmed. Of course, quarantine is essential to prevent deadly plagues in your main tank, and all treatments are much easier and quicker in containers other than your tank.
Fish Diseases: Diagnosis and Treatment, by Edward J. Noga, Blackwell Publishing, 2000 Edition.
*Formalin (Formaldehyde in solution) is proven to cause cancer, so use gloves and have good ventilation when handling and administering it.
Last edited by Fishalicious; 04-05-2009 at 08:16 PM.
36 gallon bowfront - "Hector" the Dwarf Gourami, 3 Peppered Corydoras, "Big Eric" the Rubberlip Pleco, "Killwillie" the German Blue Ram, and 9 Rummynose Tetras, 1 true Siamese Algae Eater
20 gallon long; Planted & Aquascaped (Dwarf Hairgrass, Scarlet Temple, Lace Java Fern, Red Ludwigia) - Female German Blue Ram, 4 Oto's, 11 Neon Tetras
Amazing write-up! Should help a multitude of people!
your friendly neighbourhood arowanaman!
awesome dave! Thanks for the write up!
Excellent article Dave. Thanks. Contact me on MSN sometime, I'd like to discuss some of treatment methods for Cryptocaryon.