Columnaris Disease
by Dougall Stewart BSc. (Hons)
Contents
Columnaris disease is a problem that has had a long and often confusing history. What follows is broadly divided into three main sections. Firstly, classic columnaris is briefly outlined (see
1 for further information on columnaris disease; and 2 for further information on the Flavobacteriaceae). Secondly, recent developments, specific to tropical fish are reviewed. Finally, what all this may mean to the discus hobbyist is discussed - along with a real life example and potentially useful treatments.
Classic Columnaris
Columnaris disease is a bacterial disease of freshwater fish. It is the second highest killer of farmed catfish in the USA 3, and it is widely accepted that most species of fish are susceptible to columnaris disease 4. The aetiological agent of columnaris disease is the gram negative rod bacteria, Flexibacter columnare (ex Herbert Spencer Davis 1922) Bernardet and Grimont 1989 (Synonyms: "Bacillus columnaris; Chondrococcus columnaris; Cytophaga columnaris; Flexibacter columnaris. It is often referred to as "fin rot", "cotton wool disease", "cotton mouth disease", or "saddleback disease" 3, 4.
Outbreaks tend to occur following environmental stress and clinical signs or symptoms may include yellowish brown or white lesions on the gills, skin, or fins. The bacteria attach themselves to the fish where they release protein and cartilage degrading enzymes. It may be argued that the most important site of attachment is that of the gills. The bacteria attach to the gills where they multiply, and eventually cover and destroy the entire gill filament - if untreated, substantial damage can occur, subsequently leading to the death of the fish 3.
In the early stages of the disease, the lesions may simply appear as an area that is less glossy than the surrounding scales. Advance lesions may be round or oval in shape, and can if untreated, progress to an open ulcer. In some fish the lesion may appear as a pale band, encircling the body of the fish hence the name saddleback disease 3.
Recent Developments in our understanding of Flavobacterium columnare
Prior to 1998, the majority of published works on columnaris disease primarily focused on temperate farmed fish 5. During 1998, Decostere, Haesebrouck and colleagues 4, 5, 6, 7, became the first to publicly correct this problem by isolating and studying Flavobacterium columnare directly from tropical aquarium fish. The fish species studied included black mollies Poecilia sphenops, platies Xiphophorus maculatus, guppies Poecilia reticulata, and tetras Cheirodon axelrod.
Decostere et al. 5 isolated four strains of F. columnare. Each of these strains were compared to the F. columnare reference strain, NCMB 2248, and or the 5 F. columnare strains that had previously been isolated from temperate fish. Whilst there were similarities e.g. all were gram negative flexing filamentous bacteria between 0.2-0.5mm x 5-8mm in size; all had an optimum growth rate at between 25oC and 30oC there were also significant differences amongst the strains.
Importantly, the tropical strains continued to grow at 37oC; they demonstrated a notable difference in virulence; and none were able to grow in-vitro, when immersed in a 1% NaCl (Salt) solution. In tanks where mortality occurred, the time to death following infection ranged from between 8 hours and 6 days. It was also noted, that the strains were able to enter the blood system and cause septicaemia.
The 4 type strains, which were isolated, are listed in order of virulence:
1. AJS1 was extracted from a fish with bleached and ulcerated skin, and from a tank in which daily mortality occurred.
2. AJS2 was extracted from a discoloured fish, which displayed fin rot, especially in the caudal region; in addition, there was chronic mortality in its aquarium.
3. AJS3 was extracted from a fish that displayed small white patches around mouth, opercula, and from tanks that had no significant mortality.
4. AJS4 was extracted from a discoloured fish, with pale patches on the skin and fins, especially in the dorsal region, and again from a tank that had no significant mortality.
In fish that were infected with F. columnare, the sequence of visible physical symptoms included slight swellings at the site of infection (infection was achieved by intramuscular injection of simple contact infection), which subsequently developed into a white/blanched patch. As the infection progressed, in the more virulent strains, the fish began swimming at the water surface. Shortly before death, the fish lost their ability to remain at the surface and became motionless, lying on their sides on the floor of the aquarium. AJS1 was the most virulent strain with acute mortality occurring 10 hours post-infection.
Further studies 5,7 on tropical columnaris note that the development, progress, and ultimate pathogenicity of the disease, is highly associated with the ability of F. columnare to adhere to gill tissue. AJS-1 has a high adherence ability and AJS-4 has a low ability. Therefore, as AJS-1 is the more virulent and deadly strain, the mechanism and conditions that favour attachment are of prime importance.
Factors that affect the gill adherence capability of F. columnare include: temperature, over-crowding, excessive organic loads, ionic composition of the water, excessive or poor handling, and slow movement of water. The mechanisms hypothesised to explain these occurrences are not fully understood some suggestions include:
· The slow movement of water allows the bacteria to withstand the water-flow, and turnover of the mucus cells/epithelium - thus allowing the bacteria to remain in an area where there is a high concentration of nutrients, that are efficiently obtained via slime layer localisation of dergradative enzymes.
· Ionic composition of water affects adhesion. MG++ and CA++ play a part in adhesion by reducing surface potential and repulsive forces.
· High levels of nitrites and organic matter enhance adhesion; the underlying mechanism involving nitrites is not known and it is suspected that high levels of organic matter may result in debris being trapped within themucus layer at gills thus resulting in an ideal target site for the bacteria.
· In regards to the cellular binding mechanism involved between gills and the cells, a capsule incorporated, lectin-like carbohydrate has been suggested 6.
Columnaris and the implications for the discus hobbyist
There can be no doubt that columnaris disease can occur in virtually all aquarium environments. It may be present even when there are no obvious external signs. When external signs are present, they may take the form of: yellowish brown lesions, cotton wool tufts, the fish may simply look dull or dark, or the fish may have small white patches on its fins or body. In addition to these external signs of infection, it should be noted that, one study found that in 40 % of all diagnosed cases of columnaris, the internal organs were also affected (see 3 for references).
Stress is a major factor in columnaris disease and may involve anyone, or combination of stressors e.g. low oxygen levels, high nitrite levels, comparatively high (or low) water temperatures, rough handling, mechanical injury, overcrowding, water of inappropriate hardness etc (See 8, 9 for further details on stress, fish, its management and fish health).
In discus as with other tropical fish, many of theses stressors occur during catching, bagging, transporting and subsequent reintroduction into the new aquarium. The closed re-circulating system of the aquarium is an ideal habitat for columnaris to spread and to result in high mortality rates. In addition, it is not unusual for discus to be kept in overcrowded tanks with inappropriate water parameters; or to be placed in tanks that have immature filters.
Identifying columnaris
For the discus hobbyist the external signs of columnaris to the naked eye can closely resemble the signs presented by range of other parasites. It is unlikely that the average hobbyist will have the necessary equipment, time, experience and access to the drugs that are required to be able to identify specific strains of F. columnare; however if they do, I suggest they start with references 4, 5, 6, 7 and follow up their original methodology used by the authors as a guide. However, gross identification of F. columnare is certainly achievable using a reasonable microscope, a high powered lens, appropriate accessories, and comparative slides, images, videos.
Rather than repeat information that is commonly available, I suggest that, if you are new to microscopes and the gross identification of F. columnare, that you pay a visit to the
DPH Articles Page there, you will find a collection of excellent information, images and videos.
Aside:
I often meet people who moan that microscopes and vets are expensive and a waste of time in regards tropical fish. In my experience an adequate scoping kit cost less than a decent pair of discus (certainly in the UK) and with a little practice becomes a phenomenal diagnostic tool, and may well aid the survival of your complete stock.
Secondly, if one takes along suffering stock to a vet/aqua culture specialist who has the experience and equipment to identify specific pathogenic bacteria this again can cost less than the price of a breeding pair. Be prepared to ask the individual if they have the necessary equipment for accurate identification on the premises. In saying this, I accept that you are not going to be able to use your local dog and cat vet (unless you are very lucky) Contact your local fisheries advisory board; they often keep a list which can be issued to the public of the laboratories that they use, e.g. I have used the Ministry of Agriculture, Fisheries and Food ([MAFF]; which are now the Department for Environment, Food and Rural Affairs [DEFRA] to track down the appropriate specialists in various regions of the UK for friends and colleagues. Remember your stock is potentially worth thousands it is not good sense to rely on guess work and chance when confronted by any potentially virulent disease.
Preventing columnaris
The first step in managing columnaris is to prevent its occurrence. To do this, it is important to minimise the amount of stress our fish are subjected to e.g.:
· Proper handling - use soft nets and careful netting techniques to avoid mechanical injury
· Ensure that there is adequate oxygen in shipping bags and tanks
o salt or other additives may be used to minimise the effect of shipping
· Allow a sufficient run-in period for the maturation of new tanks
o coupled with regular partial water changes appropriate to stocking density and feeding regime
· Do not overstock or keep discus in water of inappropriate hardness and pH
· When receiving new fish - ACCEPT that they have just undergone a journey that is likely to have placed them under a phenomenal amount of stress therefore, the risk of columnaris (amongst other infections) is considerably higher than normal.
o It is all to easy to blame the breeder or wholesaler when fish arrive worse for the wear and an epidemic of columnaris breaks out almost immediately the fish hits the tanks. In the main, breeders or wholesalers will take every precaution possible to ship their stock correctly - once the shipment leaves their premises though a lot can happen, from plunging pH levels, increasing carbon dioxide levels/decreases in the available oxygen, chilling of water, boxes being thrown through the air and dropped from heights.
Hopefully the above is indicative of how important it is to quarantine new stock correctly, and to take steps to reduce any population increases of ecto- and endo-parasites, that may have occurred during the relocation process. With this in mind I would like to draw attention to several points re: quarantining discus.
· A quarantine tank (qt) is not necessarily a hospital tank (although it may become one).
· It should contain a mature filter and conditioned water, prior to the new fish being added. The qt tanks water should match the water in which the discus will ultimately be placed.
· A record of observations are essential in preventing, diagnosing and treating problems e.g. temp, pH, GH, KH, behaviour, physical appearance, feeding practices, the appearance of waste etc. . . Dont forget, during the qt period you are not only making observations for visible signs of disease, you are also looking for signs of stress - the most common pre-cursor to disease outbreaks.
· Many different quarantine periods have been suggested from 1 week to 6 weeks. In my opinion the minimum for discus is 4 weeks with the preferred time being 6 weeks.
· If a 6 week quarantine period has been chosen between weeks 4 & 5 add a discus from the main tank into the qt tank, in case the newly acquired discus are unaffected carriers of, as yet, unidentified pathogens etc.
Columnaris outbreak - an example
Whilst the best cure for columnaris is prevention; F. columnare is such a ubiquitous organism, that there is a high probability that at some point in our fish keeping lives, our stock will suffer from an outbreak. The example that follows is based on a factual occurrence and the text was provided by Davis Gailitis.
One day I looked into my tank and noticed that one of my discus looked different . . . she had a spot on her left side just below the beginning of her dorsal fin. It looked like a scale had come up a bit. I now know looking back that I should have looked closer at it. I just did a casual glance and assumed that was what it was. I didn't think anything of it, except to look at it again later that day
Things stayed the same for several days and I was not overly concerned.
On the fourth day I noticed the scale that was turned up, now looked like a small pimple, all white, around 3ml in diameter and about the same in distance protruding from the body.
The next morning I looked at her when she was facing sideways to me all of a sudden I could see, in her slime coat, this white opaque haze, circular in form, about the size of an American dime.
Later that evening the opaque circle had grown t the size of an American Quarter. Up until this point, my fish had behaved normally and was eating with the rest. Tonight, she was at the back of the tank, facing the corner, and getting progressively darker.
Following discussion with Fred Goodall and further investigation - several days of treatment were performed with the result of . . . She is fine now and is horny as ****, she has also found a mate in the tank and is on a four day cycle with laying of eggs!
Davis Gailitis
In my experience Davis example is very common. It is important to mention here that this is only one manifestation of columnaris. In many cases columnaris has been known to effectively wipe-out several hundred discus in a matter of weeks; with the first deaths occurring within hours of a new shipment arriving at the retailers.
Should you be unfortunate enough to experience columnaris, the disease must be brought under control as soon as practically possible.
In Davis example, the treatment referred to, was the application of a series of salt dips, coupled with in tank temperatures of 35oC, large daily water changes using fresh conditioned water, and scrupulous tank hygiene. Below, I list a couple of methods that I have used and that have worked for me and others I have visited. If you choose to use the examples do so with great care remember, the onus is on you to make judgements regarding appropriate treatment and the current condition and status of your fish and tanks if you are unsure, nervous or need help, please ask, or seek professional advice.
Discus Salt Dip Methodology
Type of salt to use:
The type of salt used should be non-iodized and contain no free flow or other additives (e.g. no iodine or sodium ferrocyanide etc. I have used Freshwater Aquarium Salt, rock salt and sea salt. If purchasing non-aquarium salt please read the packaging carefully as current trends show an increase in the use of additives even in natural products such as rock salt (UK).
If new to Salt Dipping
If new to dipping fish a good place to start would be with a 1.5-2% salt solution; for more experienced users I would suggest you start with a 3% solution immediately. The solution should be made up in a clean bucket or spare (fishless) tank. Whilst it is preferable to weigh out the correct amount of salt e.g. for a 2% solution one would use 20g of salt per litre of water, the following approximate measure are given for the sake of simplicity.
· If your bucket/tank contains 10 litres of water you would add 13 tablespoons of salt to get an approximate 2% salt solution
· Or - If you place 3 US gallons of water in a 5 gallon bucket you would add 14½ tablespoons of salt - to get an approximate 2% solution.
And so on
· It is important to ensure that the salt is fully dissolved before placing the fish in the bucket/tank and that the water temperature matches the tank from which the fish are taken.
As you will need to multi-dip throughout the day, place a heater in the tank, if you do not want to have to remake new salt solution each time; personally I make a fresh solution for each dip.
Before you place the fish in the solution please remember that:
· The length of time that you can leave discus in the solution varies greatly from a few seconds to 30 minutes
o 5 minutes would be a reasonable average
· The time they tolerate the dip DECREASES with the number of dips performed in a 24 hour period
· The fish MUST NOT be left unattended
· During the treatment your fish may show some interesting discolouration, do not worry this is short term.
Place the fish into the solution as quickly and as carefully as possible - then observe closely.
Initially, the respiration of the fish will increase substantially, 120 gill beats per minute is not uncommon. At some point, the fish will keel over on its side - and it is at this point that the novice should remove the fishand return it to its tank. If you are confident and experienced in dipping you may want to extend the time that the fish is exposed to the saline solution - I have found it effective to leave the fish in the solution until the gill beats have slowed to around 20 bpm - irrespective of whether the fish has keeled over or not.
Once the fish are returned to their tank they should within a few minutes regain their composure. If they appear to be in difficulty, the fish can be supported using your hands and then gently pulled backwards through the water at a slow pace - so that water is forced over the gills.
I have dipped 5 times a day for up to 7 days and there has been no lasting negative effect. It is important that the dips continue until all visible signs of infection are gone.
by Dougall Stewart BSc. (Hons)
Contents
Introduction
Columnaris disease is a problem that has had a long and often confusing history. What follows is broadly divided into three main sections. Firstly, classic columnaris is briefly outlined (see
1 for further information on columnaris disease; and 2 for further information on the Flavobacteriaceae). Secondly, recent developments, specific to tropical fish are reviewed. Finally, what all this may mean to the discus hobbyist is discussed - along with a real life example and potentially useful treatments.
Classic Columnaris
Columnaris disease is a bacterial disease of freshwater fish. It is the second highest killer of farmed catfish in the USA 3, and it is widely accepted that most species of fish are susceptible to columnaris disease 4. The aetiological agent of columnaris disease is the gram negative rod bacteria, Flexibacter columnare (ex Herbert Spencer Davis 1922) Bernardet and Grimont 1989 (Synonyms: "Bacillus columnaris; Chondrococcus columnaris; Cytophaga columnaris; Flexibacter columnaris. It is often referred to as "fin rot", "cotton wool disease", "cotton mouth disease", or "saddleback disease" 3, 4.
Outbreaks tend to occur following environmental stress and clinical signs or symptoms may include yellowish brown or white lesions on the gills, skin, or fins. The bacteria attach themselves to the fish where they release protein and cartilage degrading enzymes. It may be argued that the most important site of attachment is that of the gills. The bacteria attach to the gills where they multiply, and eventually cover and destroy the entire gill filament - if untreated, substantial damage can occur, subsequently leading to the death of the fish 3.
In the early stages of the disease, the lesions may simply appear as an area that is less glossy than the surrounding scales. Advance lesions may be round or oval in shape, and can if untreated, progress to an open ulcer. In some fish the lesion may appear as a pale band, encircling the body of the fish hence the name saddleback disease 3.
Recent Developments in our understanding of Flavobacterium columnare
Prior to 1998, the majority of published works on columnaris disease primarily focused on temperate farmed fish 5. During 1998, Decostere, Haesebrouck and colleagues 4, 5, 6, 7, became the first to publicly correct this problem by isolating and studying Flavobacterium columnare directly from tropical aquarium fish. The fish species studied included black mollies Poecilia sphenops, platies Xiphophorus maculatus, guppies Poecilia reticulata, and tetras Cheirodon axelrod.
Decostere et al. 5 isolated four strains of F. columnare. Each of these strains were compared to the F. columnare reference strain, NCMB 2248, and or the 5 F. columnare strains that had previously been isolated from temperate fish. Whilst there were similarities e.g. all were gram negative flexing filamentous bacteria between 0.2-0.5mm x 5-8mm in size; all had an optimum growth rate at between 25oC and 30oC there were also significant differences amongst the strains.
Importantly, the tropical strains continued to grow at 37oC; they demonstrated a notable difference in virulence; and none were able to grow in-vitro, when immersed in a 1% NaCl (Salt) solution. In tanks where mortality occurred, the time to death following infection ranged from between 8 hours and 6 days. It was also noted, that the strains were able to enter the blood system and cause septicaemia.
The 4 type strains, which were isolated, are listed in order of virulence:
1. AJS1 was extracted from a fish with bleached and ulcerated skin, and from a tank in which daily mortality occurred.
2. AJS2 was extracted from a discoloured fish, which displayed fin rot, especially in the caudal region; in addition, there was chronic mortality in its aquarium.
3. AJS3 was extracted from a fish that displayed small white patches around mouth, opercula, and from tanks that had no significant mortality.
4. AJS4 was extracted from a discoloured fish, with pale patches on the skin and fins, especially in the dorsal region, and again from a tank that had no significant mortality.
In fish that were infected with F. columnare, the sequence of visible physical symptoms included slight swellings at the site of infection (infection was achieved by intramuscular injection of simple contact infection), which subsequently developed into a white/blanched patch. As the infection progressed, in the more virulent strains, the fish began swimming at the water surface. Shortly before death, the fish lost their ability to remain at the surface and became motionless, lying on their sides on the floor of the aquarium. AJS1 was the most virulent strain with acute mortality occurring 10 hours post-infection.
Further studies 5,7 on tropical columnaris note that the development, progress, and ultimate pathogenicity of the disease, is highly associated with the ability of F. columnare to adhere to gill tissue. AJS-1 has a high adherence ability and AJS-4 has a low ability. Therefore, as AJS-1 is the more virulent and deadly strain, the mechanism and conditions that favour attachment are of prime importance.
Factors that affect the gill adherence capability of F. columnare include: temperature, over-crowding, excessive organic loads, ionic composition of the water, excessive or poor handling, and slow movement of water. The mechanisms hypothesised to explain these occurrences are not fully understood some suggestions include:
· The slow movement of water allows the bacteria to withstand the water-flow, and turnover of the mucus cells/epithelium - thus allowing the bacteria to remain in an area where there is a high concentration of nutrients, that are efficiently obtained via slime layer localisation of dergradative enzymes.
· Ionic composition of water affects adhesion. MG++ and CA++ play a part in adhesion by reducing surface potential and repulsive forces.
· High levels of nitrites and organic matter enhance adhesion; the underlying mechanism involving nitrites is not known and it is suspected that high levels of organic matter may result in debris being trapped within themucus layer at gills thus resulting in an ideal target site for the bacteria.
· In regards to the cellular binding mechanism involved between gills and the cells, a capsule incorporated, lectin-like carbohydrate has been suggested 6.
Columnaris and the implications for the discus hobbyist
There can be no doubt that columnaris disease can occur in virtually all aquarium environments. It may be present even when there are no obvious external signs. When external signs are present, they may take the form of: yellowish brown lesions, cotton wool tufts, the fish may simply look dull or dark, or the fish may have small white patches on its fins or body. In addition to these external signs of infection, it should be noted that, one study found that in 40 % of all diagnosed cases of columnaris, the internal organs were also affected (see 3 for references).
Stress is a major factor in columnaris disease and may involve anyone, or combination of stressors e.g. low oxygen levels, high nitrite levels, comparatively high (or low) water temperatures, rough handling, mechanical injury, overcrowding, water of inappropriate hardness etc (See 8, 9 for further details on stress, fish, its management and fish health).
In discus as with other tropical fish, many of theses stressors occur during catching, bagging, transporting and subsequent reintroduction into the new aquarium. The closed re-circulating system of the aquarium is an ideal habitat for columnaris to spread and to result in high mortality rates. In addition, it is not unusual for discus to be kept in overcrowded tanks with inappropriate water parameters; or to be placed in tanks that have immature filters.
Identifying columnaris
For the discus hobbyist the external signs of columnaris to the naked eye can closely resemble the signs presented by range of other parasites. It is unlikely that the average hobbyist will have the necessary equipment, time, experience and access to the drugs that are required to be able to identify specific strains of F. columnare; however if they do, I suggest they start with references 4, 5, 6, 7 and follow up their original methodology used by the authors as a guide. However, gross identification of F. columnare is certainly achievable using a reasonable microscope, a high powered lens, appropriate accessories, and comparative slides, images, videos.
Rather than repeat information that is commonly available, I suggest that, if you are new to microscopes and the gross identification of F. columnare, that you pay a visit to the
DPH Articles Page there, you will find a collection of excellent information, images and videos.
Aside:
I often meet people who moan that microscopes and vets are expensive and a waste of time in regards tropical fish. In my experience an adequate scoping kit cost less than a decent pair of discus (certainly in the UK) and with a little practice becomes a phenomenal diagnostic tool, and may well aid the survival of your complete stock.
Secondly, if one takes along suffering stock to a vet/aqua culture specialist who has the experience and equipment to identify specific pathogenic bacteria this again can cost less than the price of a breeding pair. Be prepared to ask the individual if they have the necessary equipment for accurate identification on the premises. In saying this, I accept that you are not going to be able to use your local dog and cat vet (unless you are very lucky) Contact your local fisheries advisory board; they often keep a list which can be issued to the public of the laboratories that they use, e.g. I have used the Ministry of Agriculture, Fisheries and Food ([MAFF]; which are now the Department for Environment, Food and Rural Affairs [DEFRA] to track down the appropriate specialists in various regions of the UK for friends and colleagues. Remember your stock is potentially worth thousands it is not good sense to rely on guess work and chance when confronted by any potentially virulent disease.
Preventing columnaris
The first step in managing columnaris is to prevent its occurrence. To do this, it is important to minimise the amount of stress our fish are subjected to e.g.:
· Proper handling - use soft nets and careful netting techniques to avoid mechanical injury
· Ensure that there is adequate oxygen in shipping bags and tanks
o salt or other additives may be used to minimise the effect of shipping
· Allow a sufficient run-in period for the maturation of new tanks
o coupled with regular partial water changes appropriate to stocking density and feeding regime
· Do not overstock or keep discus in water of inappropriate hardness and pH
· When receiving new fish - ACCEPT that they have just undergone a journey that is likely to have placed them under a phenomenal amount of stress therefore, the risk of columnaris (amongst other infections) is considerably higher than normal.
o It is all to easy to blame the breeder or wholesaler when fish arrive worse for the wear and an epidemic of columnaris breaks out almost immediately the fish hits the tanks. In the main, breeders or wholesalers will take every precaution possible to ship their stock correctly - once the shipment leaves their premises though a lot can happen, from plunging pH levels, increasing carbon dioxide levels/decreases in the available oxygen, chilling of water, boxes being thrown through the air and dropped from heights.
Hopefully the above is indicative of how important it is to quarantine new stock correctly, and to take steps to reduce any population increases of ecto- and endo-parasites, that may have occurred during the relocation process. With this in mind I would like to draw attention to several points re: quarantining discus.
· A quarantine tank (qt) is not necessarily a hospital tank (although it may become one).
· It should contain a mature filter and conditioned water, prior to the new fish being added. The qt tanks water should match the water in which the discus will ultimately be placed.
· A record of observations are essential in preventing, diagnosing and treating problems e.g. temp, pH, GH, KH, behaviour, physical appearance, feeding practices, the appearance of waste etc. . . Dont forget, during the qt period you are not only making observations for visible signs of disease, you are also looking for signs of stress - the most common pre-cursor to disease outbreaks.
· Many different quarantine periods have been suggested from 1 week to 6 weeks. In my opinion the minimum for discus is 4 weeks with the preferred time being 6 weeks.
· If a 6 week quarantine period has been chosen between weeks 4 & 5 add a discus from the main tank into the qt tank, in case the newly acquired discus are unaffected carriers of, as yet, unidentified pathogens etc.
Columnaris outbreak - an example
Whilst the best cure for columnaris is prevention; F. columnare is such a ubiquitous organism, that there is a high probability that at some point in our fish keeping lives, our stock will suffer from an outbreak. The example that follows is based on a factual occurrence and the text was provided by Davis Gailitis.
One day I looked into my tank and noticed that one of my discus looked different . . . she had a spot on her left side just below the beginning of her dorsal fin. It looked like a scale had come up a bit. I now know looking back that I should have looked closer at it. I just did a casual glance and assumed that was what it was. I didn't think anything of it, except to look at it again later that day
Things stayed the same for several days and I was not overly concerned.
On the fourth day I noticed the scale that was turned up, now looked like a small pimple, all white, around 3ml in diameter and about the same in distance protruding from the body.
The next morning I looked at her when she was facing sideways to me all of a sudden I could see, in her slime coat, this white opaque haze, circular in form, about the size of an American dime.
Later that evening the opaque circle had grown t the size of an American Quarter. Up until this point, my fish had behaved normally and was eating with the rest. Tonight, she was at the back of the tank, facing the corner, and getting progressively darker.
Following discussion with Fred Goodall and further investigation - several days of treatment were performed with the result of . . . She is fine now and is horny as ****, she has also found a mate in the tank and is on a four day cycle with laying of eggs!
Davis Gailitis
In my experience Davis example is very common. It is important to mention here that this is only one manifestation of columnaris. In many cases columnaris has been known to effectively wipe-out several hundred discus in a matter of weeks; with the first deaths occurring within hours of a new shipment arriving at the retailers.
Should you be unfortunate enough to experience columnaris, the disease must be brought under control as soon as practically possible.
In Davis example, the treatment referred to, was the application of a series of salt dips, coupled with in tank temperatures of 35oC, large daily water changes using fresh conditioned water, and scrupulous tank hygiene. Below, I list a couple of methods that I have used and that have worked for me and others I have visited. If you choose to use the examples do so with great care remember, the onus is on you to make judgements regarding appropriate treatment and the current condition and status of your fish and tanks if you are unsure, nervous or need help, please ask, or seek professional advice.
Discus Salt Dip Methodology
Type of salt to use:
The type of salt used should be non-iodized and contain no free flow or other additives (e.g. no iodine or sodium ferrocyanide etc. I have used Freshwater Aquarium Salt, rock salt and sea salt. If purchasing non-aquarium salt please read the packaging carefully as current trends show an increase in the use of additives even in natural products such as rock salt (UK).
If new to Salt Dipping
If new to dipping fish a good place to start would be with a 1.5-2% salt solution; for more experienced users I would suggest you start with a 3% solution immediately. The solution should be made up in a clean bucket or spare (fishless) tank. Whilst it is preferable to weigh out the correct amount of salt e.g. for a 2% solution one would use 20g of salt per litre of water, the following approximate measure are given for the sake of simplicity.
Worked examples (See Table 1 for other strengths):
· If your bucket/tank contains 10 litres of water you would add 13 tablespoons of salt to get an approximate 2% salt solution
· Or - If you place 3 US gallons of water in a 5 gallon bucket you would add 14½ tablespoons of salt - to get an approximate 2% solution.
And so on
· It is important to ensure that the salt is fully dissolved before placing the fish in the bucket/tank and that the water temperature matches the tank from which the fish are taken.
As you will need to multi-dip throughout the day, place a heater in the tank, if you do not want to have to remake new salt solution each time; personally I make a fresh solution for each dip.
Before you place the fish in the solution please remember that:
· The length of time that you can leave discus in the solution varies greatly from a few seconds to 30 minutes
o 5 minutes would be a reasonable average
· The time they tolerate the dip DECREASES with the number of dips performed in a 24 hour period
· The fish MUST NOT be left unattended
· During the treatment your fish may show some interesting discolouration, do not worry this is short term.
Place the fish into the solution as quickly and as carefully as possible - then observe closely.
Initially, the respiration of the fish will increase substantially, 120 gill beats per minute is not uncommon. At some point, the fish will keel over on its side - and it is at this point that the novice should remove the fishand return it to its tank. If you are confident and experienced in dipping you may want to extend the time that the fish is exposed to the saline solution - I have found it effective to leave the fish in the solution until the gill beats have slowed to around 20 bpm - irrespective of whether the fish has keeled over or not.
Once the fish are returned to their tank they should within a few minutes regain their composure. If they appear to be in difficulty, the fish can be supported using your hands and then gently pulled backwards through the water at a slow pace - so that water is forced over the gills.
I have dipped 5 times a day for up to 7 days and there has been no lasting negative effect. It is important that the dips continue until all visible signs of infection are gone.
Salt Solution |