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
4.1.2.1 Dosage in water
4.1.2.2 Dosage in food
4.1.3
Additional notes on metronidazole
4.1.3.1 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.
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.
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).
|
Family |
Common
'English' Name |
|
Anabantidae |
Labyrinths e.g. Gouramies |
|
Belontiidae |
Paradise Fish |
|
Cichlidae |
Discus, Angels, Uaru, Oscars |
|
Acanthuridae |
Surgeon fishes |
|
Pomacentridae |
Damselfishes |
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 & Nohynkova
(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
Source:
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.
|
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 (±.) and peripheral ridge (².) 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).
Source:
Paul, 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..
Source:
Paul, 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.
|
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).
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.
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.
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.
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.
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.
4.1.2.1.1
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.
4.1.2.1.2
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.
•
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
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
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.
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.
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.
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.
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 - what's
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.
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.
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.
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 gil
