Treating White Spot Disease
By Frank M. Greco, AnimalForum.com
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Copyright 1997 by Frank M. Greco. Reprinted with permission.
Aquarticles
The common name for this disease is white spot disease or Ich. The scientific name
is Ichthyophthirius multifilis, and the organism is ciliated protozoan.
Symptoms: Obvious white spots
on the body and/or fins of the infested fish. Spots may resemble grains of salt. The spots
(actually, cysts) may be up to 1 mm in diameter, or may join together to form irregular
patches. Heavily infested fishes may scratch themselves on the bottom or tank decor, and
rapid respiration may be evident.
Life cycle: Adult parasites,
which feed upon the tissue of the fish, fall into the substrate layer. There, it divides
many times, producing several hundred tomites which are the infective stage. The tomites
swim into the water column in search of a host and, failing to find one, die in a short
time. If they do find a host, the tomites attach and encyst. The life cycle is temperature
dependent, and can occur in three to four days at 70 degrees F and up to five weeks at 50
degrees F. At lower temps, the parasite will remain dormant.
Treatment: As long as the
parasite is encysted on the fish, it is immune to treatment. However, at the first notice
of these cysts, treatment should be started. Malachite green is generally safe to use for
most freshwater species. I know some of you must be shaking your heads, saying that
malachite green will kill some freshwater species. Nonsense! When dosed correctly,
malachite green is safe for even the most so-called sensitive species.
The correct dose is 0.05 ppm malachite green for
three treatments, one every other day. At this level, your fish should not experience
malachite sensitivity. Of course, dosing at 0.05 ppm means doing more than adding one drop
per gallon. To figure out the correct amount of liquid to add, you take the concentration
of malachite green listed on the bottle (in percent), and convert it to milligrams per
milliliters (percent= 1 gram/100 milliliters of water). Divide the milligrams per
milliliters by the final concentration. This will give you the results in
milliliters/liters. To convert to gallons, divide the number of milliliters by 3.8.
For example, we have a 10 gallon tank, want a
final concentration of 0.05 ppm (or 0.05 mg/l. It's interchangeable for our purposes), and
we are using a 0.75% malachite green solution. So...0.75% = 7.5 mg/milliliter. 7.5 mg/ml
divided by 0.05 ppm (or mg/l) = 1 ml per 40 gallons. Since 1 milliliter is about 16 drops,
we will need 1/4 of that, or 4 drops per 10 gallons of a 0.75% malachite green solution.
Now for the kicker: Most medications advise one
drop per gallon. This works out to 2.5 times the amount actually needed. No wonder some
hobbyists lose fish when using malachite green: they have severely overdosed.
Another popular treatment is the use of aquarium
or marine salt. Bringing the level to 5 ppt will generally eradicate the parasite. Some
catfishes may be sensitive to this salt level, and so if you do have catfish in your tank,
go no higher than 2 ppt. In either case, use whatever level you choose as an indefinite
bath for 14 days.
Also, it has been noted that raising the
temperature will also "cure" the condition, but I would advise against this
because:
An increased temperature also increases the
metabolism of the fish, which causes it to require more oxygen. However, there is less
oxygen in the water the higher you go with the temperature. This produces more of a stress
on the fish, and may delay a full recovery.
The use of temperature alone
is not necessarily a cure. While it may accelerate the life cycle, it does not guarantee a
100% kill.
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