Spironucleus vortens

alias "Hex", HITH and HLLE

By: Fred Goodall & Dougall Stewart 


i.  Foreword
ii.   Abstract

1.  Introduction – Common Symptoms

2.  Erroneous identification


3.  Spironucleus
3.1     Where are flagellates found in discus

3.2     ‘Holes’, organ/systemic infection and jelly excreta

3.3     The transmission of Spironucleus.


4.  Treatments

4.1     Metronidazole

4.1.1  Safety rationale and the horror stories

4.1.2  Dosage     Dosage in water     Dosage in food

4.1.3  Additional notes on metronidazole     How the medication works

4.2     Secondary infections and stubborn cases


5.  Food and its role in ‘holes’ and other symptoms

5.1     Dietary vitamins, minerals and trace elements

5.1.1  Vitamins

5.1.2  ‘Vitamin, mineral and trace element’ – WARNING!

5.1.3  Red Wrigglers - Eisenia foetida


6.  Management and or avoidance of Spironucleus vortens ‘outbreaks’ – A holistic approach


7.  Other fun stuff – or ‘it’s a fact Jack’


8.  Conclusion


9.  Science and the fish hobbyist – a final word


10.  Acknowledgments


11.  References


12.  Endnotes:

i.  Foreword

The text that follows has been written as a ‘working document’ for those that are faced with a case of ‘Spironucleus’ or a gestalt of ‘Spiro-type’ symptoms.  The authors advise that it should not be considered in isolation, and that it is vital that the reader draws on a wealth of other high quality information. Only then, can the reader make an informed judgement on the symptoms experienced and follow an appropriate treatment regime that takes into account their specific localised parameters.


The use of ‘I’ in this document has occasionally been used for simplicity’s sake, and is indicative of a shared point of view unless otherwise indicated. 

ii.   Abstract

This article considers the correct identification of the pathogen said to be responsible for HITH, HLLE, Hex etc and considers the symptoms and treatments from a holistic point of view.  The identity of the organism involved is Spironucleus vortens and epizootic proportions of these flagellates results in an overworked immune system, severe dietary deficiency, jelly like excreta and a number of behavioural problems.  Attempted cures should avoid ‘misleading, over simplistic, single causation theories’ and focus on a regime of correct environmental parameters, healthy diet and appropriate medication.  Metronidazole is the current drug of choice and is comparatively safe to use in discus aquaria – dosages are suggested as guidance.  The role of diet in the occurrence of ‘holes’ and the recovery of this fish is also discussed – along with some popularly myths and misconceptions that are currently held.

1.  Introduction – Common Symptoms

The majority of us will have heard of, or in many cases, have had fish that have suffered from the following symptoms:

  • a darkening in colours
  • a tendency to ‘hang’ in corners, or to remain in isolation from other fish, even at feeding
  • a tendency to stare at food but without eating it, or if it does take a sample it immediately spits it out again
  • the decline in food acceptance, is often accompanied or followed by lethargy, and a reduction in muscle tissue which gives the fish a ‘pinched’ appearance behind the head and the skin ‘texture’ may take on a roughened appearance
  • white, jelly like excreta can often be seen trailing from the anal vent, on the floor of bare bottom aquaria, or sometimes white, stingy ‘rotted plant-like material’ is ‘adrift’ in the aquarium
  • the wasted fish may develop a bloated stomach region
  • skin lesions may start to appear, especially on the body and the head, in the region of the  lateralis system – these holes may eventually expand and connect to from considerable size ‘craters

Over the years there have been many names attributed with the above symptoms.  Some of these include: 

  • Hole in the head disease - HITH
  • Head and Lateral Line Erosion - HLLE
  • Hex
  • Flagellate Infestation
  • Holes disease
  • Hexamitiasis
  • Wasting Disease
  • Spironucleus
  • Malawi Bloat
  • Dropsy

The list is almost as endless at the range of causative phenomena and cures that have been attributed to the above symptoms.  My aim in writing this paper is to introduce to the discus hobbyists some of the recent developments that have been made in the identification of the causative organism, for what I will refer to, from here on in, as ‘Spironucleus’; and also to consider some of the methods and implications for treating a Spironucleus infestation in Discus Symphysodon  species.

2.  Erroneous identification

Many species of marine and freshwater fish commonly host parasitic flagellates (see table 1 for some examples).  These flagellates tend to be found in the lumen of their digestive tract, systemically, and less frequently on the skin of their host.   In the past, where diplomonad flagellates involved, they were ascribed to the genera of: Hexamita, Octomitus and Spironucleus (Poynton, Sterud, 2002).  


Common ‘English’ Name


Labyrinths e.g. Gouramies


Paradise Fish


Discus, Angels, Uaru, Oscars


Surgeon fishes



Table 1

An example of several families of fish (and their common English names) that are affected by pathogenic diplomonads infestations. 

It is also suggested that the only genre involved is that of Spironucleus.

However, due to the limitations of light microscopy, the size and nature of the flagellates involved and the lack of high quality identification keys that used easily identifiable morphological differences - much of the earlier identifications appear to be erroneous. 

Evidence is mounting that suggests that all of the 15-20 species of diplomonads that have been found on fish, and described and stored in reference collections - need to be reconsidered.  This is exemplified by the fact that recent studies have neither found true Hexamita nor Octomitus species in/on ANY species of fish.  This statement is based on  work that involved the accurate description of the above genera and the employment of transmission electron microscopy (TEM) which allows the investigator to accurately identify internal ultrastructural features which can then be used as an aid to genera and species identification (see figures 1, 2, 3; also Poynton, Sterud, 2002 for full details). The cry for clarity is not new - it has been growing in vigour since Kulda & Lom’s work in the sixties and was catalysed by TEM work by Brugerolle and more recently by Poynton and Sterud; and Paull and Matthews. 

Figure 1 - Principal distinguishing features of the three genera of diplomonads within the suborder Diplomonadina

Note especially the presence or absence of flagellar pockets (cytostomal canals) (evident as sheaths around the recurrent flagella of Spironucleus and Hexamita, and absent from Octomitus), shape of the nuclei, and locations of kinetosomes and tract of the recurrent flagella passing posteriorly.

Surface ornamentation, microtubular bands and endoplasmic reticulum are excluded for simplicity, and flagella are shortened in this illustration.

Original by Judith A. Stoffer after Brugerolle (1974), Brugerolle et al. (1973b, 1974) and Kulda & Nohýnková (1978). © 2001 Judith A. Stoffer.

Original Illustration by
Judith A. Stoffer

Figure 2 - (a-d) Surface ultrastructure of Spironucleus vortens. (a) Ventral or dorsal view of whole organism, (b) lateral view showing compound lateral longitudinal ridges, note the broad central part bordered by a peripheral ridge which is narrower on the left than on the right (the peripheral ridge has a rope-like appearance), (c) ventral or dorsal view of posterior end showing counter-crossing of right peripheral ridges around exits of recurrent flagella, also note the papillae, and (d) lateral view of posterior end showing counter-crossing of right peripheral ridges around exits of recurrent flagella. Abbreviations: (b) bacterium; (cr) central ridge; (lpr) left peripheral ridge; (o) opening of flagellar pocket (cytostomal canal); (p) papilla; (r) recurrent flagellum; and (rpr) right peripheral ridge (bars=1 m).

Figure 3 - (a-i) Diplomonad flagellates prepared by different techniques and viewed by light microscopy.  (a,b) Fresh preparation of spherical and elongate trophozoites of Spironucleus torosa viewed by Nomarski illumination
(c,d) smear preparations of S. torosa stained by Protargol silver protein
(e) preparation of S. vortens stained by Protargol silver protein (filter method)
(f) unidentified diplomonads (arrow) from blood smear stained with Leishman's Giemsa  (g) culture of S. barkhanus stained with DAPI (4-6-diamidino-2-phenylindole) and exposed to bright field and UV illumination  (h) S. torosa in tissue section (lumen of rectum) stained by the Feulgen reaction  (i) S. torosa in tissue section (lumen of rectum) stained with haematoxylin and eosin.

Figures  1-3


Originally published  in Poynton, S L & Sterud, E; (2002), ‘Guidelines for species descriptions of diplomonad flagellates from fish’, Journal of Fish Diseases, 25:1, 15-31, and reproduced with permission.

 3.  Spironucleus

In discus, the prime organism responsible for much of the woe described above has been identified as Spironucleus vortens (an organism that also affects other cichlids e.g. Angels, Pterophyllum scalare, P. Altum etc (Paull and Matthews, 2001).  S. vortens has an elongated body that is approximately 8 to 14 µm long & 3 to 6 µm wide.  It has 6 anterior and 2 posterior flagella and possesses 2 sigmoid shaped, elongated nuclei; TEM is required for accurate identification of the ultrastructural organelles (see figures 1-8).

Figures 4, 5, 6

Correctly identified SEM of Spironucleus vortens.  Extracted from head lesions on a discus.

Note shape of body and arrangement of the 8 flagella, each of which taper terminally culminating in a small bulb. (B) Note prominent lateral compound ridge (α) and peripheral ridge (β) extending the length of the body. (C) Posterior region of S. vortens. Note elaborate swirls of the peripheral ridge and papilla on the base of each terminal flagella (arrowed)


Paull, G C; Matthews, R A, (2001), ‘Spironucleus vortens, a possible cause of hole-in-the-head disease in cichlids’, Diseases of Aquatic Organisms, 45: 3; 197-202 and reproduced with permission

Figures 7 & 8

Symphysodon discus. Photographs of a discus with moderate hole-in-the-head infection. (Left) Side view. Small regular-shaped holes around the eyes and mouth. (Right) Head-on view of the same fish. Note bilaterally symmetrical holes.|


Paull, G C; Matthews, R A, (2001), ‘Spironucleus vortens, a possible cause of hole-in-the-head disease in cichlids’, Diseases of Aquatic Organisms, 45: 3; 197-202 and reproduced with permission



3.1     Where are flagellates found in discus

Paull and Matthews (2001) were able to isolate S. vortens from the intestine, kidney, liver, spleen, and head lesions of discus; and also from the intestine and head lesions of angelfish. In addition, studies by Somboon (2002) found S. vortens in the blood, stomach, intestine, spleen, gall bladder, and ovaries of angel fish.  Somboon also found S. vortens in apparently healthy fish.

Paull and Matthews (2001) note that S. vortens interacts with the gut wall of the discus, attaching itself to the intestinal mucosa. In addition, they suggest that there may well be some form of intracellular interaction within epithelial cells lining the intestine. If the flagellates reach epizootic proportions they suggest that it is via the invasion of the lamina propria (loose connective tissue/mucosa) that systemic entry, and infection of additional organs, especially the liver, may be achieved. Paull and Matthews (2001; and many others) suggest that it is at this point of dissemination that an infestation S. vortens becomes lethal. 

In simple terms, in ‘healthy discus’ S. vortens is commonly found in the flagellated stage in the lumen of the upper intestine, where it remains, controlled by the immune system of the fish.  In stressed discus, the immune system is placed under greater strain, and the organism, in theory, multiplies unchecked causing considerable localised damage. Once the damage is severe enough the intestinal lining is penetrated and the S. vortens enters the blood causing systemic and organ infections.  In regards to stress, I have stated elsewhere (Stewart, 2001) that stressors can include: low oxygen levels, high nitrite levels, comparatively high (or low) water temperatures, rough handling, mechanical injury, overcrowding, water of inappropriate hardness etc (see Francis-Floyd, 1997; Rottmann, Francis-Floyd, Durborow, 1992 for more information on stress and its effects and management).

3.2     Holes, organ/systemic infection and jelly excreta

As mentioned above, Paull & Matthews (2002) found S. vortens, to some degree, in all of the fish that they studied – including the controls.  In addition, S. vortens were isolated from the lateralis lesions of the fish studied, which supports Bassleer’s 1983 work.  It was suggested that the flagellates either caused the holes through ‘direct infection’ (least likely); or that, the ‘host tissue underneath the skin or indirectly by blocking the tiny blood vessels that supply the sensory system’ (most likely).  If one, takes into consideration the nutrient deficiencies that are said to occur during severe and systemic infections it is no wonder that the lateralis system begins to disintegrate.  Of the cases studied by Paull and Matthews (2001) where the external manifestations of S. vortens were severe, S. vortens had always progressed to the liver, spleen and kidney.   In the less severe cases the parasite had yet to progress to the aforementioned organs and ‘in these instances the infection appeared to be in a state of remission’.

In regards to the ‘jelly’ excreta found in aquaria, one often reads comments such as ‘it is only the stomach lining of the fish – and is perfectly harmless’.  This needs addressing. The stomach lining or for that matter, the whole of the epithelial cells of the digestive tract undergo constant replacement, day in day out.  For sufficient to be shed to be fully visible and of considerable dimensions, either the fish has been turned inside out, or there is a problem. At this point it should be noted that feeding meat-mixes based on gelatine can result in the discus passing ‘a sheet of membrane like whitish material’ and this should not be confused with what is being discussed.  Importantly, in discus the final protein uptake occurs in the intestine, not the stomach.  It is in the intestine that the ‘protein digesters’ of: trypsin, chymotrypsin and metalloproteases are found (Chong et al., 2002). Their location and the findings by Paull & Matthews (2001) is indicative that if, and this is a big if, the sheet of whitish material being passed is ‘lining’, it is intestinal lining ,and may well be the product of  protein digesters, and flagellate damage to the lumen and mucosa.  In addition, their evidence helps explain why ‘hole closure’ occurs post nutritional supplementation.

3.3     The transmission of Spironucleus.

Whilst there is little known at the moment on the complete lifecycle and transmission of Spironucleus vortens it is reasonable to expect that it is very similar to other Spironucleus species. One way that Spironucleus may be transmitted is via contaminated faecal material.  That is the adult trophozoite undergoes longitudinal binary fission in the intestine, the trophozoites are then passed in faeces.  It may also be possible that cysts are produced and evacuated in a similar manner, though this is yet to be demonstrated; however other diplomonads have reproduced in this manner under laboratory conditions (Poynton, Sterud, 2002).  In this way, discus ‘pecking’ at the base of the aquarium are likely to ingest S. vortens.  Post ingestion excystment would occur, if cysts are involved; and/or the newly ingested trophozoites would start to colonise the mucosal surface and mucus layer of the small intestinal lumen – and so the cycle continues.

4.  Treatments

Today the most common treatments propounded are ‘vitamins and minerals - that is all you need this will cure everything’, ‘heat treatment - crank the temps and kill all bugs’, ‘metronidazole the fish - chuck it in the tank and in 3 days your fish will be breeding babies by the millions and be laughing and smiling’, or ‘it’s a wire, it’s a wire, your fish has eaten halfway through the heater cable and is being blasted by stray voltage’, and finally I suspect that there are those that think S. vortens is in fact a killer bug devised by some discus super power (which happens to be the only person with a cure) and is simply one step in global discus domination.

Therefore I will try to treat this section fairly and rationally in the hope that people will see that 1 factor in isolation – does not a cure make and that the problem often needs a more holistic approach. 

4.1     Metronidazole

4.1.1  Safety rationale and the horror stories

When one recommends the use of metronidazole in the treatment of fish on many of the ‘popular’ forums - there is often a cry of ‘be warned it is mutagenic and carcinogenic and your fish will die a thousands deaths’.  Whilst I am firm believer in ‘warnings’ on the overuse of drugs, I do feel that at times their expedient use may well be appropriate and safe. 

In respect to the mutagenic and carcinogenic warnings, often those postings refer to information extracted from ‘clinical statistical results’ and quote the results as statistical certainties for ‘normal’ dosing levels of the drug involved.  The trouble with this is if you look in a Physician’s Desk Reference (PDR), what tends to catch the eye is the glaring warnings on ‘chronic, high dose’, and it often takes 20 minutes or more of detailed reading to realise that what is in fact being referred to is a dose that is taken orally at 5X the recommended dose, for 30 days or you IV the drug for 3 days at 3X the recommended dose.  It is this information that is the foundation of the ‘statistical’ results on mutagenic activity, and often takes the form of an ‘assay’ – i.e. not in a mammal, (in chemicals, as opposed to live animals).

Taking the above into account, current ‘recommended’ dosage, and the half life of metronidazole I consider the risk that our discus are going to develop three heads or become riddled with cancer a week later, reasonably minimal.

4.1.2  Dosage     Dosage in water

This is the option for non-eating discus.  Firstly it should be remembered that metronidazole in water is assumed to enter the fish like most antibiotics, across the gill membranes and directly into the blood stream - and many of the ‘older’ doses were calculated on just that.  However, it is our opinion that the delivered dose is considerably lower than the ‘older hobby science’ portrays.  The evidence to support this is that the medical literature states that metronidazole in IV solutions has a 6 - 8 hr half life, it is temperature sensitive either side of its optimum, and at temperatures under ~ 28oC it can precipitate out of solution. Furthermore, it is light sensitive whilst in solution, and will begin breaking down on exposure.  Now none of us IV our discus, but we do expose the metronidazole to an illuminated aquatic environment, high temps, and for some considerable period of time.  Therefore, there is no way that a professional ‘standard’ dose can be calculated if the metro is going to be added to the water in this manner – there are simply to many individual random variables to take into consideration.  At best, one can come up with an ‘informed’ suggested dosage – that may need adapting according to individual parameters and needs.

Therefore the dosages we list below are based on our personal experience, informed reading and the results of application.     Dose 1  - The average case of white poos.

This is where the Spironucleus has been spotted early i.e. the discus has demonstrated a change in behaviour - indicative of an S. vortens infestation; white poo may have been seen on 1 or 2 occasions (at the most – it is believed that by the time this jelly excreta has developed the population of S. vortens is already at considerable levels); and preferably S. vortens has been grossly identified using a compound light microscope.

*      A 30% water change prior to dosing

*      A temperature of 30oC

*      250mg of metronidazole / 10gallons of aquarium water.

*      After 8 hours 25% water change is performed followed by another 250mg of metronidazole / 10gallons of aquarium water.

*      This cycle is repeated for three days 

*      Note: mortar and pestle the tablet/s, add a drop of warm aquarium water and mix to thick paste; keep adding drops until you have a thinner paste; – you can then add more water, mix thoroughly and spread over the aquarium.     Dose 2 – Severe case or reoccurrence

This is where the Spironucleus has not been spotted early i.e. the discus has demonstrated a behavioural change indicative; white poo may have been seen on several occasions and the fish may in fact no longer be passing visible excreta; or this is a repetition of a previous case of S. vortens; again has been grossly identified using a compound light microscope.

*      A 30% water change prior to dosing

*      A temperature of 30oC

*      400mg of metronidazole / 10gallons of aquarium water.

*      After 8 hours 25% water change is performed followed by another 400mg of metronidazole / 10gallons of aquarium water.

*      This cycle is repeated for three days

*      The dose of metronidazole can be increased further than this, I have a personal preference of 500mg but greater care must be taken and careful observations are a must.

Remember other factors play a role as to how much actually gets to where it is needed and as to how effective the dose will be, e.g. age, metabolism, temps, other medications, water, degree of infestation, immune system efficiency etc.

Please remember the doses are not meant to be a ‘be all and end all’ of cures - other factors must be taken into consideration.     Dosage in food

*      Mixing

The mixing of medicated food is of vital importance - the preferred method is to mortar and pestle the tablet, ‘grind it with the end of a wooden rolling pin; then roll out the food, on some grease proof paper, so that it is thin and flat.  Then sprinkle the powder thinly and evenly over the food and knead it in. The mix is then rolled up and placed into mixing bowel where it is very carefully mixed so that an even distribution of the drug is assured.

*      Dosage

*      The preferred dose is (Francis-Floyd & Reed, 1994; Yeng, 2001) i.e. 1gm of metronidazole to 100gm of Fred’s beef heart mix or similar.

*      Again I have increased this dose considerably where warranted  When preparing a medicated mix, it is important to use appropriate amounts as there is a life expectancy once the drug has been added to the food.

*      The medicated food, if stored should be frozen

*      Feeding the medicated food

*      Some suggest that normal feeding 3x day for 3 days is the best way.  A recommended alternative is small portions throughout the day, ensuring that all of the food is eaten i.e. it should not remain on the bottom after a minute or two.  This can continue for up to 10 days

4.1.3  Additional notes on metronidazole     How the medication works

The normal tissues of our bodies require oxygen to survive and to function correctly

If an area occurs that is deprived of oxygen, for whatever reason, e.g. as is the case with abscessed tissues and or tumours, an anaerobic growth zone allows the development of anaerobic bacteria infections e.g. Spironucleus vortens (or facultative anaerobes e.g. the Vibrionaceae – Vibrio sp., Aeromonas sp.), and the necrotisation of soft tissue.

In anaerobic conditions, ‘the metronidazole molecule changes so as to inhibit the DNA repair enzymes that normally would repair cells. This means death for anaerobic bacteria’ but has no effect on aerobic tissues.   In addition, it ‘normalises’ excessive immune reactions, especially in the gut. The specific mechanisms underpinning this function are currently being investigated (Brooks, 2002, DVM, DABVP).

It is widely accepted that metronidazole is most effective when given with food

4.2     Secondary infections and stubborn cases

Evidence (Somboon & Smith, 1999) suggests that a 3 day treatment is only suitable for mild or early diagnosed cases of S. vortens and that once remission starts to occur in these cases, the immune systems continues with the recovery process.   If there are ‘complicating factors’, e.g. it is not in fact an early diagnosis, damage is severe, or the treatment has been ineffectually repeated as if often the case – then the likelihood that epizootic numbers will reappear is very considerable.  What’s more there is a real probability that a secondary infection may take hold e.g. competition within the anaerobic zone during non-treatment time or systemic gram-negative aerobic bacteria (during treatment or post treatment but not fully recovered).  In the more severe cases, it is our preference to treat for septicaemia - as a real precaution.

5.  Food and its role in ‘holes’ and other symptoms

In regards to healing the ‘holes’ that are present on a discus, or even ‘curing’ a flagellate infestation - it is often stated that all an individual needs to do is to increase the ‘dietary value’ of the food being fed to the fish.  The most common supplements include: vitamins C, D and B complex along with the minerals Calcium, Potassium and Phosphorus, plus additional trace elements.  This is pretty difficult and pointless if the fish is not eating in the first place - though it is a great preventive measure, and good practice, for all manner of woes.

5.1     Dietary vitamins, minerals and trace elements

5.1.1  Vitamins

The information here based on Untergasser (1991) and general reading.  I strongly suggest that for serious hobbyists, Untergasser’s book, although slightly dated, is well worth reading - even for the nutritional work alone

*      Vitamin C - Ascorbic acid.

Mammals to some extent can produce this for D-Glucose; however fish cannot.  Therefore, they must obtain this essential vitamin from their food.  A lack of vitamin C leads to a degradation of normal connective tissue and an increase in the permeability of cell membranes.  This may result in tissue that is easily ruptured and haemorrhages under the skin, especially in the area of the lateralis system.  Self healing is retarded, the fish becomes more susceptible to pathogens and there is a risk of skeletal and nervous system deformities/problems

Importantly the degradation of vitamin C is accelerated in the presence of light, oxygen, heat, copper, a base ( pH over 7.2 ) solution and high nitrate levels.

*      Vitamin D - the calciferols

It is stored in the liver and is essential for optimum calcium-phosphate (c/p) metabolism i.e. if it is absent then c/p cannot be absorbed by the intestinal mucosa.  Therefore c/p that would have been used for bone formation is used for general body maintenance.  It is important that if the diet is to be supplemented with vitamin D then calcium and phosphate should also be given.

It should be noted that it is possible to overdose vitamin D which can cause a demineralisation of the skeletal system.  The calcium is removed and deposited in the renal tubules and as result the body’s ability to excrete toxic metabolites decreases - often with fatal results.

*      Vitamin B complex (Thiamine is the only covered for this revision)

Thiamine is essential for the reduction of carbohydrates and healthy thyroid function.  It is resorbed via the mucosa, reacts with phosphate in the liver.  A deficiency leads to a disruption of muscle and nerve function, lethargy, body deformation, weight loss and haemorrhaging.

Thyroid note: The thyroid produces numerous hormones.  The majority are variable in function and are still being studied. However, it is thought that, to some extent, that the thyroid plays a role in controlling the rate of oxygen consumption, and maintaining metabolic homeostasis of carbohydrates and proteins.  It also produces hormones which affect growth, motor function, and the central nervous system.

*      Calcium

Calcium is required for the formation of bone and the correct metabolic activity of the blood, nerves and heart i.e. it is essential as a cofactor for extracellular enzymes and proteins and vital in the integrity of skeletal and soft tissue and as a biological messenger in nerve excitation and muscle contraction, initiates hormonal secretion, and functions in intracellular regulation.  Calcium regulation and homeostasis in freshwater fish is via the gills, gut, and kidney (Hollis, 1997; Untergasser, 1991).  Uptake is achieved in the presence of vitamin D and may be inhibited in the presence of oxalic acid (calcium is converted into an insoluble salt)– a common constituent of many plants.  Other inhibitors include an excess of fibre which contains phytic acid; this combines with calcium in the intestines, forming an unusable calcium compound.  An excess of protein and or sodium increases the excretion of calcium.  It can be seen that the repercussions of feeding an unbalanced diet are serious indeed.

*      Potassium

Amongst most life functions, potassium is essential in maintaining the following systems: blood, endocrine, digestive, nervous; and also heart, kidneys, muscular and cellular functions.  A deficiency results in, decreased blood pressure, lethargy, nervousness, irregular heartbeat, and poor reflexes.  The deficiency affects the transmission of nerve and muscle impulses and prevents ‘normal’ chemical reactions within the cells.

*      Phosphorus

Phosphorus is essential for maintaining electrolyte balance.  A deficiency leads to the irregularities in the skeletal structure, brain cells and nervous system, circulatory systems digestive system, eyes, and the liver.  Deficiency symptoms include loss of appetite, lethargy, breathing gill beat irregularities and problems with several internal organs.  Phosphorus must be in balance with magnesium and calcium.

5.1.2  ‘Vitamin, mineral and trace element’ – WARNING!

Whilst ‘vitamin mineral and trace element’ theories – in theory – are great.  They should not be treated in isolation as the sole reason for ‘holes’ and lateral line erosion. It should be remembered, that when feeding these supplements as a ‘cure’ – most play some part in the ‘normal’ healing process so it is incorrect to suppose that it is a deficiency of these elements is the ultimate causation of ‘holes’.  It is well known that fish fed these supplements on a regular basis, can and do develop holes and lateral line erosion; and that the indiscriminate use of vitamins, minerals and trace elements can leaded to severe and permanent damage.

5.1.3  Red Wrigglers - Eisenia foetida

There is one organism above all others that is constantly propounded and a cure for S. vortens - that is the RED WRIGGLER Eisenia foetida.  The question I ask is why should it reach this lofty status.  E. foetida has been used as fish bait and as a fish food supplement since the 1930s (Mason, et al., 1992).  Most cry of its high nutritional value and simply see it as a vitamin and mineral supplement.  Personally I think it is considerably more complex than that; whilst E. foetida is well known as a phenomenal source of minerals e.g.  calcium, magnesium, and as a ‘trace elements warehouse’ - it is well known as a ‘miraculous’ enzyme factory and on the downside, as a metal ions e.g. cadmium, copper and zinc and pesticides accumulator - so one has to ask what is really happening to S. vortens during the feeding of E. foetida.  Is there some other anti-microbial effect occurring in addition to the dietary supplementation?  Taking this into account it is important that the source of live E. foetida is taken into consideration.  They are very easy to breed and have a great re-cycling effect in general - so I suggest that if you want to feed your own E. foetida that you cultivate your own culture to minimise the risk of contamination from undesirable sources.

*      Red Wrigglers - whats in a name?

In the above paragraph I have tried to refer to the correct scientific name of E. foetida  as opposed to ‘Red Wrigglers’; this is because the effects may well be species specific and there are many other worms that have a similar name or are sold as red wrigglers here are a few for your enjoyment; all are composting worms

*      The Real Red Wrigglers - Eisenia foetida, common names: tiger worm, garlic worm, manure worm, and brandling worm.

*      Red Worms - Lumbricus rubellus, another composting worm.  In sunlight it is very active. Red Worms, Blood Worms, and Red Wiggler (see the confusion in common names)

*      Red Tiger Worms - Eisenia andrei, Common names: Tiger Worm and Red Tiger Hybrid.

*      Night Crawlers - Eisenia hortensis, Common names: Belgian Worms European Night Crawler, Night Crawler

§         General info on worms may be found at: Nurturing Nature.

6.  Management and or avoidance of Spironucleus vortens ‘outbreaks’ – A holistic approach

Firstly one should start with healthy stock – this can only be determined by close observation and a suitable quarantine period.  I have mentioned this elsewhere but I believe fervently in proper quarantining procedures.

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 tank’s water should match the water in which the discus will ultimately be placed.  A record of observations is essential in preventing, diagnosing and treating problems e.g. temp, pH, GH, KH, behaviour, physical appearance, feeding practices, the appearance of waste etc. . . Don’t 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.

During the QT period - If evidence warrants it - take steps to reduce any detrimental population of ecto- and endo-parasites.

Ok, assuming that you have healthy stock. The next step is to consider the water. For general keeping I suggest 28-30oC, GH 7 or less, KH 7 or less and a healthy functioning bio-filter coupled with water changes (in the region of 10% per day or greater for fish stocked at 2 adult discus per 10 gallons of water in a bare bottom tank).

Under normal circumstances discus are able to utilise minerals from their diet or from the water.  If the water is devoid of minerals and the diet questionable and monotonous then there is a real risk to the health of the fish.  This goes some way to explaining why magnesium sulphate and other water mineralisation products appear to assist in the healing processes of sick fish.

In regards to diet, I have already mentioned Fred’s beef heart mix and the value of clean Eisenia foetida.  This should be supplemented with small amounts of:

*      quality branded food dry foods (preferably pre-soaked)

*      clean prawns, cockles, brine shrimp

*      gamma irradiated frozen food

*      All are comparatively acceptable compared to the use of  wild live foods’.

If an outbreak of S. vortens occurs, for whatever reason, then the above is a must, in effecting a ‘quality cure’. In other words, make sure you have the water parameters correct, don’t assume check.  Check temperature, pH, GH, KH, ammonia, nitrites and nitrates, and if using tap water check for chloramines, copper etc – all of this takes minutes.  Assuming that you are feeding a good balanced diet, and you have identified S. vortens grossly from symptoms or grossly using a microscope, then it is time to treat with an appropriate drug.  Allow time for the drug to work; and allow time for the fish to heal.

Evidence suggests that, after 72 hours a ‘cure’ is not affected.  It is simply that the S. vortens population has been ‘knocked’ back to 50% of its pre-treatment epizootic proportions (Somboon & Smith 1999).  Perhaps at this point the immune system can deal with the flagellate loading and the body is able to repair the damaged tissue.  However it should be noted that extended exposure of up to 10 days to metronidazole may expedite the healing process considerably.

7.  Other fun stuff – or ‘it’s a fact Jack’

Some of the information that follows has a degree of scientific evidence to support it but is often quoted out of context or decreed as the only reason/cure for ‘holes’ and or S. vortens – almost to the point where it becomes completely ludicrous and down right dangerous.  This is the real danger of looking for a single cause or attempting to make sweeping statements for a ‘be all end all’ solution to a problem – it is only through knowing as many parameters as possible and making educated decisions that you can truly investigate and propose solutions.

Science in regards to the discus hobbyists re meds, disease and anything else for that matter, is not the enemy of hobbyists but a sound working tool.  The ‘Everybody says/knows’ does not make ‘science’ nor ‘facts’.  Since the 1960’s in fresh water tropical ‘fish keeping’ a lot of ‘hobby science’ has taken root over any and all advances in the bio sciences, including the tremendous strides made in disease, nutrition and treatments for food fish and ornamental fish.

7.1     Heat treatment on its own – will cure all cases of Spironucleus infestation

 There can be no doubt that raising the temperature of the aquarium water will raise the metabolic activity of the discus and increase the overall effectiveness of the immune system - this point I do not argue.  In addition it is suggested that the microbes have a shorter life cycle; yet it is often forgotten that it also raises the rate at which microbes multiply (not good).  This concerns us, as the indiscriminate use of heat as a 100% cure all for S. vortens, that is often propounded, can be downright deadly; and it should always be remembered that the correct use of heat rests on an incredibly fine balance.

There have been reports that doing this on its own will ‘effect’ a cure and eradicate S. vortens.  Well, if the infestation is a mild one - the raise in temperature will increase the metabolic rate of S. vortens and increase the immune system response, however, there must come a point where the discus is at a greater risk from the temperature than the pathogen.  Especially when one takes into consideration that a temperature in excess of 37C (see table 2) is required and that in response to an excessive rise in temperature the fish will attempt to ‘control its body temperature’ by: a decrease in general activity to reduce excess heat produced by metabolic processes; increase its rate of gill beats to increase the effectiveness of heat exchange between its blood and the water; and have to deal with an environment of ever decreasing oxygen content; and the overall effect that excess heat will have on the enzyme system of the fish.



Optimum temperature

28-31o C

Greatest survivability temperature

22o C

Intolerable temperature

37o C

Optimal pH


Optimal growth pH


Optimal survivability pH


Intolerable pH

<5.5 >8.5

Table 2
Spironucleus vortens
grown In vitro
Source: extracted from text (Somboon & Smith 2000)

7.2     Stray voltage

There are those that would suggest that you affix electrical grounding to the tank as it has been suggested that epithelium interaction and degradation of the lateralis system is possible - assuming the stray voltage doesn’t kill your fish or yourself first.

 Personally, if I suspect that a piece of equipment may be ‘leaking current’ I replace the piece of equipment - and fast.

7.3     Antibiotic "gel/paste"

There are those that suggest the application of an antibiotic paste or gel is a ‘cure for’ S. vortens. This is not the case.  If used wisely it will protect the fish from secondary infections and reduce the numbers of S. vortens present in the ‘pits’ short term.  However, the infection at this time must be systemic and it is highly likely the organs are also infected - therefore it would make more sense to use an appropriate drug in the food and to treat the infection where it matters than to simply apply a topical remedy - to me this is like bailing out a battleship that has a torpedo in its side.

7.4     Filter carbon

It is alleged that carbon adsorbing the ‘vitamins’ and or trace minerals directly from the tank water. Erm, lets say this is a tad questionable as I am not sure which vitamins are being referred to and that are found in ro/tap water??? And whilst SOME heavy metals may be removed by carbon, depending on pore size, ‘activation method’, flow rate etc, in industrial units – to suggest that total depletion is achieved in an aquarium is questionable to say the least.  For those that dose the tank water at with Vit C and the ‘Duplavit’ it is more likely that a deficiency of these in the tap water is due to water that has not been changed before the fish, plants and bacteria have used them up.  In addition, one would assume that the fish are receiving a balanced died and that most prepared fish foods are rich in vitamins, minerals and trace elements.  Moreover, one would have to ask why does HITH develop in tanks that have never been subjected to carbon filtration.

7.5     Garlic & Pumpkin seeds

Garlic & Pumpkin seeds are two substances often quoted as cured for intestinal worms and even on occasion as anti-flagellates.  Whilst there can be know denying that the items need proper scientific investigation.  It does no harm to acknowledge that garlic extract has antimicrobial and antimutagenic capabilities and is a source for potassium, phosphorus, B and C vitamins, as well as calcium - pumpkin seeds are a known source of phosphorus.

8.  Conclusion

Hopefully, from the text here it can be seen that the symptoms above should never be automatically attributed to a single factor – and to do so would be ludicrous. In all probability the symptoms are multifactorial.  On occasion some ‘holes’ and other symptoms may simply be the result of a nutritionally deficiency, which can be corrected fairly readily.  However where there is a gestalt of symptoms, there is a high probability that the flagellate Spironucleus vortens is at work.  During the infection the fish will be deprived of essential nutrients, trace elements etc. and its immune system will be working overtime to control the outbreak.  Once epizootic proportions of  S. vortens are reached, there will be considerable damage to the intestinal lumen and if holes are present on the lateralis system of the fish then in all probability the infection has become systemic and the organs are starting to fail – prognosis at this point is not good.  Treatments should take on a holistic approach and must be thorough, carefully planned and should not stop before time.  In severe cases secondary infections must also be considered and dealt with appropriately.

9.  Science and the fish hobbyist – a final word

It is sad to see the effect of a small minority of ‘hobbyist forum posters’ for this total disregard for easily proven and researched science.  Often we read the quote ‘the simple way’ and ‘always worked before’ or the even better ‘if it isn’t broken, don’t fix it’.  The way we see it is that:

. . . ‘simplicity’ is an art form not to be underestimated or used blindly;


it is  not an excuse for gross stupidity;


 it is correct to keep things simple because you have a wealth of: information, intelligence and experiences to back up the ‘on the surface simplicity’.

Dougall Stewart & Fred Goodall

We remember when ‘Tetracycline’ was the ‘miracle cure’ and was supposed to eradicate Columnaris from the hobby.  Medical doctors at the same time were warning patients not to request tetracycline for colds and ‘not feeling up to par’ and trying to use it as a ‘tonic’ or we might have resistant ‘bugs’; as was the case with the general use of Penicillin, the antibiotic that tetracycline replaced.  After all, bacteria are bacteria, medications are medications . . . what on earth would make a person think that just because it is being added to their aquarium that the laws of science stop working? 

My (Fred) first medicine chest for my hobby had salt, methelyene blue, penicillin vk hydrate, quinine and mecurichrome and was ‘state of the art’ for 1963-64, but not very effective in 2002.  We must learn, adapt and correct our false ‘knowledge’, grow with the body of human knowledge as it does - and importantly – to apply it wisely.. We owe it to our fish to at least educate ourselves enough to not hurt them with folklore in place of sound treatments. 

With the above in mind, this document should not be seen ‘The Answer to HITH’, it is simply a working document bringing together ideas and recent developments.  We fully acknowledge that as time passes we will learn much more on S. vortens and the various occurrences of ‘holes’ and ‘jelly poo’ – we accept that – in fact we relish that – and hopefully over time this document will be as dynamic as the science that underpins it.

Our kind regards

Dougall Stewart & Fred Goodall 


10.   Acknowledgments

We wish to thank:

Walter Soestbergen
for his generosity in allowing this information to be shared with discus enthusiast from around the globe .

My Father
To my father for teaching me, Fred, to question ‘facts’ that have only one verifying source. 

Gregory Paul & Tony Matthews
For their kindness in granting permission to use their images; and for the great insight they have provided into Spironucleus vortens

Sarah Poynton, & Judith A. Stoffer
For their permission to use several illustrations; and for their superb work on diplomonads. 

And most importantly – to the those ‘DPH posters’
who are prepared to agree, disagree, challenge ideas and stimulate the thought processes
– with one desired aim –
the increase in the survivability of our beloved Discus fish
- a special thanks to Rob, Bert, Tony, Davis, Tom, Colleen - 

To Bwian
for covering for me (Dougall) whilst writing this document,
and for reminding us that shoes are tools
to be worn on the feet of those that
walk the walk
and not gods to be worshipped.


11.  References

Andrews C (1990) ‘The ornamental fish trade and fish conservation’.

Brooks, W. C., (2002), ‘Flagyl’, Veterinary Information Network

Chong, A.S.C., Hashim, R., Chow-Yang, L., Ali, A.B., (2002), ‘Partial characterization and activities of proteases from the digestive tract of discus fish (Symphysodon aequifasciata)’, Aquaculture, 203: 321–333

Francis-Floyd, R., (1997), ‘Stress - Its Role in Fish Disease’, Circular 919: Department of Fisheries and Aquatic Sciences, Florida, University of Florida

Francis-Floyd, R., Reed, P., (1994), ‘Management of Hexamita in Ornamental Cichlids’, VM 67, Department of Large Animal Clinical Sciences, Florida: Institute of Food and Agricultural Sciences, University of Florida

Goodall, (2001), ‘Beefheart Recipe’, Discus Page Holland, in URL: http://www.dphnet.com/sub-article/cat-01/beefheart1.shtml

Hollis, L., (1997), ‘Calcium Balance and its Regulation in Freshwater Fish and Mammals’, c/o Mc. Master University

Mason, W.T. Jr., Rottmann, R.W., Dequine, J.F., (1992), ‘Culture of Earthworms for Bait or Fish Food’, Circular 1053, Department of Fisheries and Aquatic Sciences, Florida Cooperative, USA: Institute of Food and Agricultural Sciences, University of Florida

Paull, G C; Matthews, R A, (2001), ‘Spironucleus vortens, a possible cause of hole-in-the-head disease in cichlids’, Diseases of Aquatic Organisms, 45: 3; 197-202

Poynton, S. L., Sterud, E., (2002), ‘Guidelines for species descriptions of diplomonad flagellates’, Journal of Fish Diseases, 25:1; pp 15

Rottmann, R.W.; Francis-Floyd, R.; Durborow, R.; (1992), ‘The Role of Stress in Fish Disease’, Southern Regional Aquaculture Centre Publication, Publication No. 474

Somboon, S., (2002), ‘Spironucleus vortens of the Freshwater Angelfish (Pterophyllum Scalare): Growth Requirements, Chemotherapeutants, Pathogenesis and Immunity’, Abstract of thesis dissertation, Virginia Tech (VetMed Library)

Somboon, S., Smith, S. A., (1999), ‘Efficacy of various chemotherapeutic agents on the growth of Spironucleus vortens, an intestinal parasite of the freshwater angelfish’, Diseases of Aquatic Organisms, 38:1

Somboon, S., Smith, S. A., (2000), ‘In vitro studies on optimal requirements for the growth of Spironucleus vortens, an intestinal parasite of the freshwater angelfish’, Diseases of Aquatic Organisms, 39:2

Stewart, D. J., (2001), ‘Columnaris Disease Revisited, Discus Page Holland’, in URL: http://www.dphnet.com/sub-article/cat-02/columnaries.shtml

Untergasser, D., (1989), ‘Handbook of Fish Diseases’, TFH Publications

Untergasser, D., (2000), ‘Discus Health (Selection, Care, Diet, Diseases & Treatments for Discus, Angelfish, and Other Cichlids)’, USA: TFH Publications

Yeng, S., (2001), ‘Penang Discus Eng Ed.’ Penang: Nura Discus


12.  Endnotes:

High quality information – Peer Reviewed Journals

In regards to high quality information, we are of the belief that the reader must draw on two key factors:

  1. Consider peer reviewed journals e.g. Journal of Fish Diseases, Diseases of Aquatic Organisms etc.

*    Whilst is it impossible nor desirable to state what peer review means for all journals, there are a few important points which underpin their academic validity and why they make a brilliant first point of call

*    The process of peer reviewing is not just a case of reading and agreeing with the material.  There is a tendency for 3 or more reviewers to be involved and for final comments to be made by the editors.  On occasion, procedures are repeated by external parties and comparisons are made to the original study; often before results are published in the magazine. Frequently, there is a built in delay from the publishing arena or a ‘holding period’ whilst the article is sent out to key contributors/interested parties for investigation, correction or updating.

  1. Consider experience – never underestimate experience, it is a vital ingredient in any rational justification for diagnosis, prognosis and treatment etc.  However experience should always be tempered with scientific rationale and never followed blindly.



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