White Spot
White spot is arguably the most common disease that tropical
fish are subject to, and is believed to be responsible for
causing more fatalities than any
other disease. Most – if not all – aquarists will encounter
white spot (also known as Ich) at least once or twice during the course
of their
career/hobby.
What is it?
White spot is a single-celled, ciliate protozoan.
In regular English, this means it’s a single celled parasite organism, which propels itself through
the water through use of cilia, or filament-like hairs. Mature adult cells
are 0.5 – 1.0 mm in size, and are usually clearly visible to the
naked eye.
White spot is a parasite. It lives under the
top layer of scales and skin on your fish, eating skin cells
and causing minute cellular ruptures. The white
spots which result from these ruptures are the basis for the parasite’s
name, and are what will eventually kill the host (the fish).
How does it get into my tank?
White spot is usually introduced to a tank along with new, infected fish or
plants. It can also break out seemingly without warning in an undisturbed tank.
When this happens, it means that the organism
has been present for some time, but has been dormant (hibernating),
and that some new stimulus – stress,
or a change in water temperature – has caused it to awaken and become
active.
The original cell of the organism will attach itself to a host (the weakest,
oldest, or sickest fish in the tank), usually in the gill plates or under the
scales.
After approximately one week of parasitism, the now-mature organism (mature
Ich cells are called trophozoites) detaches from the fish and settles on a
new surface: usually, a plant or ornament.
It will then form a capsule around itself (called
a cyst) and will remain dormant – at least, outwardly
- for about a week. During this period of time, the cell within
the capsule is furiously dividing: by the time that
those seven days are up, that one cell has become approximately 1,000 new
single-celled organisms.
These “daughter cells” will then
break loose and swim freely about the tank, attaching themselves
to new fish - and beginning the cycle all over
again.
White spot is highly contagious and progresses very rapidly. 100% mortality
is to be expected unless something is done about it.
Prevention is obviously the best cure:
Make sure you only ever buy healthy fish from a reputable, clean breeder
Inspect the tank from which your fish originate: does it look to be in clean
condition? Are the plants healthy and flourishing? Is the gravel clean of
sediment and dust? Is the water warm and well-conditioned?
Check the fish, too – not just the ones you’re buying, but all
the fish in the tank. Watch out for ones that are ‘hiding’ (under
rocks and behind ornaments) since this is a classic symptom of an infected
fish. Make sure none are displaying those tell-tale white spots
Thoroughly clean any gravel or ornaments you purchase before placing them in
the tank, to make sure any cysts are dislodged
Quarantine new plants and fish for one week before adding them to your tank
Never overstock your tank, since it will stress the fish (which is a major
contributor to outbreaks of white spot, as well as dictating in part the severity
of the outbreak)
Check your fish regularly for white spots. The earlier you detect it, the less
impact the disease will have on your tank.
What if it’s too late for prevention?
If you’ve already got an outbreak in your own tank, relax – it
may be a serious illness, but at least it’s easy to cure!
The most common, and user-friendly, method of curing condition is through
the use of aquarium salts.
Parasites are less tolerant of salt than fish,
so adding extra salt kills off all the Ich organisms with no
adverse effects to the fish themselves. Make
sure you follow the instructions on the package (aquarium salts should
always come with clear instructions), and make sure before
using it that you don’t
have any salt-intolerant fish in the tank like Neons, Cardinals, Glow-Lights,
or scale-less Catfish, which are easily burned by salt.
A second alternative is to use a chemical called
malachite green. This is an effective way of treating Ich,
but unfortunately the chemical is toxic to
humans (as well as most plants and snails, so make sure you remove these
before commencing treatment!). Always use gloves when administering
this chemical – and,
because it’s teratogenic (meaning it harms fetuses), pregnant women
should stay well away from it.
All you have to do with malachite green is
remove the carbon from the filter, and add the appropriate
amount (according to the instructions) to the water
of the tank. It usually takes about 4-5 days to kill all the Ich cells – a
good rule of thumb is to continue use of it until a couple of days after
the last white spot has vanished from the fish. 10 days is typical for
use of malachite
green: just remember to put the carbon back in the filter to remove any
lingering traces of the treatment, and give it one or two more days before
putting the
snails and plants back in.
UV light is also an effective means of treatment: you can purchase inner-tank
filters from the pet store with small UV lights inside them. The light kills
the parasites in the capsule stage, before they attach to the host.
The transfer method is time-consuming but effective:
you’ll need to
move all the fish, daily, into a new tank with clean, warm, conditioned water.
It takes about 7 daily transfers (so, a week) for all the parasites to fall
behind. The only downside is that the fish (and, often, the aquarist!) get
stressed by the process, leaving them more susceptible to other diseases. Fish
already affected by white spot will sometimes die during the transfer process
because their bodies can’t handle the additional stress.
For a complete compendium of information on
all the problems that tropical fish are subject to, take a
look at Katy’s Tropical Fish –
A
Complete Guide.You’ll learn how to keep your fish happy, healthy,
and beautiful, how to keep your aquarium to professional standards, how
to troubleshoot health
problems as soon as they occur, and learn valuable insider tips and tricks
for keeping your aquarium looking spectacular.
To check out Katy’s Tropical Fish, just
click on the link below:
