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FRESHWATER QUARANTINE PROCEDURE
For those of you quarantining freshwater fish, please read on. For those dealing with marine
species, please skip down three paragraphs.
For freshwater fishes, the quarantine procedure is quite simple:
First, you will want to feed your fish an antibacterial medicated food twice a day for 14
days. Feed as much as the fish will eat in 2 minutes or so at each feeding. Bacterial disorders
are the most common cause of death in fishes, and it pays to give a preventative treatment
here. If you are dealing with wild-caught fishes, you will also want to supplement this with
an antiprotozoal medicated food (antibacterial diet at one feeding and antiprotozoal at the
other) to rid these fish of whatever intestinal parasites they may be carrying. There are antiparasitic diets that contain both an antiprotozoal and an antibacterial, and this type of food
can be substituted in place of the two separate diets.
Next, you will want to treat the fish with malachite green. 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 dose I use, and have been successful with, 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 (10 percent =
1000 milligrams per 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 liters 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 malachite green based medications advise ONE DROP PER GALLON of a 0.75% solution. 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!
Anyway..to continue...
You want to dose at least three times, once every other day for three treatments, all the while
feeding the medicated food(s). While the malachite treatment will last only six days, you
really want to continue the quarantine for another eight days. If after this time period no
obvious signs of disease are present, you may safely add the fish to your established tank.