Parasite-S: Product Information

PARASITE-S- formaldehyde liquid
Western Chemical Inc.


PARASITE-S is the aqueous solution of formaldehyde gas (this is equivalent to formalin 37% or
37grams of formaldehyde in 100mLof solution). U.S.P. grade PARASITE-S contains not less than
37% (by weight) of formaldehyde gas per weight of water and 6 to 14% methanol. In solution, formaldehyde
is present chiefly as HO(CH20)H. Its molecular weight is 30.93. PARASITE-S is readily
miscible with water, methanol, and ethanol and is slightly soluble in ether. It is a clear, colorless
liquid (Heyden Newport Chemical Corporation, 1961).


The toxicity of PARASITE-S was measured by standard methods in laboratory bioassays with
rainbow trout, Atlantic salmon, lake trout, black bullhead, channel catfish, green sunfish, bluegill,
smallmouth bass, largemouth bass and striped bass. The 3,6,24 and 96-hour LC50 (lethal
concentration for 50% of the animals) values for trout range from 1,230 to 100 μL/L (455 to 37 ppm
formaldehyde); for catfish, from 495 to 65.8 μL/L (183 to 24 ppm formaldehyde); for bluegill,
from 1,230 to 100 μL/L (455 to 37 ppm formaldehyde); for catfish, from 495 to 65.8 μL/L (183 to 24 ppm formaldehyde);
for bluegill, from 2,290 to 100 μL/L (847 to 37 ppm formaldehyde); for largemouth bass,
the values for 6 to 96-hour LC50 range from 1,030 to 143 μL/L (381 to 53 ppm formaldehyde) (Bill et al. 1977)
and for striped bass the values for 6 to 96-hour LC50 range from 940 to 30 μL/L (347 to 11 ppm formaldehyde)
(Bills, Marking and Howe-1993). The 24, 48, 72 and 96 hour LC50 values for penaeid shrimp range from 712 to 250 µL/L (ppm) (Johnson. 1974 and Williams, 1980).


1. Parasiticide for Finfish: for the control of external protozoa (Chilodonella spp., Ichthyobodo spp., Epistylis spp., Ichthyophthirius spp.,Ambiphrya spp. and Trichodina spp.), and the monogenetic trematode parasites (Cleidodiscus spp., Dactylogyrus spp., and Gyrodactylus spp.).

2. Parasiticide for Penaeld Shrimp: for the control of external protozoan parasites (Bodo spp., Epistylis spp., and Zoothamnium spp.).

3. Fungicide for Finflsh Eggs: for the control of fungi of the family Saprolegniaceae.

4. Fungicide for Freshwater-reared Finfish: for the control of mortality due to saprolegniasis associated with fungi in the family Saprolegniaceae.


1. Parasiticide for Finfish

Concentrations of Formalin

Aquatic Species Administer in Tanks and Raceways for up to 1 hr (µL/L)* Administer in Earthen Ponds (Single Treatment) (µL/L)*
Salmon and Trout Up to 170 15-25** ***
Above 50
Below 50 Up to 250 15-25** ***
All other Finfish Up to 250 15-25** ***

*Microliter per liter *(µL/L) = parts per million (ppm)

** use the lower concentration when ponds are heavily loaded with phytoplankton or fish, to avoid oygen depletion due to the biological oxygen demand created by the decay of dead phytoplankton. Although the indicated concentrations might be used if strictly monitored.

*** Although the indicated concentrations are considered safe for cold and warm water finfish, a small number of each lot of pond to be treated should always be used to check for any unusual sensitivity to formalin before proceeding.

2. Parasiticide for Penaeld Shrimp

Concentrations of Formalin
Aquatic Species Administer in Tanks and Raceways for up to 4 hr (µL/L)* Administer in Eartehn Ponds (Single Treatment) (µL/L)*
Penaeid Shrimp 50 to 100 ** 25***

* Microliter per liter (L/L) = parts per million (ppm).
** Treat for up to 4 hours daily. Treatment may be repeated daily until parasite control is achieved.
Use the lower concentration when ponds, tanks or raceways are heavily loaded with phytoplankton,
or shrimp, to avoid oxygen depletion due to the biological oxygen demand created by
decay of dead phytoplankton. Alternatively, a higher concentration might be used if dissolved
oxygen is strictly monitored.
*** Treatment may be repeated in 5 to 10 days, if needed

3. Fungicide for All Finfish Eggs

Concentrations of Formalin
Aquatic Species Administer in Hatchery Systems (µL/L)*
Eggs of all finfish except Acipenseriformes 1000-2000 for 15 minutes **
Eggs of Acipenseriformes Up to 1500 for 15 minutes **

* Microliter per liter (µL/L) = parts per million (ppm)

** Apply in constant flow water supply of incubating facilities. A preliminary bioassay should be conducted on a small subsample of fish eggs to determine sensitivity before treating an entire group. This is necessary for all species because egg sensitivity can vary with species or strain and the unique conditions at each facility.

4. Fungicide for Freshwater-reared Finfish

Concentrations of Formalin
Aquatic Species Administer in Tanks and Raceways (µL/L)*
Freshwater-reared Finfish 150 for 60 minutes per day on alternate days for three treatments

*Microliter per Liter (µL/L) = parts per million (ppm)


APPLICATION TO TANKS AND RACEWAYS -Turn off water supply, provide aeration, apply
appropriate amount of PARASITE-S, and thoroughly dilute and mix to assure equal distribution of
PARASITE-S. Treat for up to 1 hour for fish and up to 4 hours for penaeid shrimp, then drain the
solution and refill the tank with fresh, well-aerated water. While tank is under treatment, adequate
oxygen must be present to maintain the fish or shrimp. If needed. aeration should be provided to
prevent oxygen depletion. Treatments may be repeated daily until parasite control is achieved.
APPLICATION TO PONDS — Apply greatly diluted PARASITE-S to the pond evenly using a pump,
sprayer, boat bailer, or other suitable device to assure even distribution. Allow PARASITE-S to dissipate
naturally. Single treatments usually control most parasites, but may be repeated in 5 to 10 days if
needed. Treatments for Ichthyophthirius should be made at 2-day intervals until control is achieved.
APPLICATION TO EGG INCUBATORS — Apply PARASITE-S into a constant water supply flowing
around the eggs. A drip or pressure system should be used and timed. Apply PARASITE-S under
the surface of the water flow.

Zero days.


Striped bass have been demonstrated to be hypersensitive to formalin; lethal toxicity has been
noted to occur at levels approximately 2-3 times the recommended therapeutic concentration.


Use Personal Protective Equipment(PPE) including eye, respiratory, and skin protection while handling this product. Refer to SDS and OSHA regulations(29 CFR 1910.1048) for guidance on the most appreciate PPE equipment. Failure to use PPE may increase the risk of unsafe exposure to formaldehyde.

Exposure to high concentrations of formaldehyde vapor causes severe respiratory irritation
which can be life-threatening. Lower vapor levels can cause irritation to the eyes, respiratory
tract, and skin. Swallowing formaldehyde can be life-threatening. Formaldehyde is an irritant
when splashed on skin or Into the eyes. It can cause severe eye damage, even blindness.

Keep out of reach of children.

In laboratory animals, formaldehyde has demonstrated the potential to cause reproductive and developmental toxicities at high dose.

Use only with adequate ventilation.

Keep container tightly closed when not in use.

May aggravate a pre-existing asthmatic condition and allergic rhinitis.

Moderate fire and explosion hazard exists when exposed to heat or flame.

Contains methanol — cannot be made non-poisonous. Prolonged exposure to methanol has
been associated with reproduction disorders.

Potential Cancer Hazard: Formaldehyde vapor may be carcinogenic if inhaled. Use applicable
safety protection. (Note: This drug, used as labeled, does not cause formaldehyde
tissue residues in fish).

Employers: Refer to Occupational Safety and Health Administration (OSHA) regulation 29
CFR 1910.1048 for human safety guidance that may be applicable to your specific operation.
OSHA’s “action level” concentration for airborne formaldehyde is 0.5 part per million
(ppm), calculated as an 8 hour time-weighted average (TWA). Use respiratory, skin, and eye
protection when needed (refer to OSHA’s regulation 29 CFR 1910.1048). OSHA’s airborne
exposure limits (without use of a respirator) for formaldehyde shall not exceed 1) 0.75 part
per million (ppm) as an 8-hour, time-weighted average (TWA) or 2) 2 parts per million (ppm)
as a 15-minute, short term exposure limit (STEL). NOTE: The odor of formaldehyde in the air
can generally be detected at about 0.5 to 0.8 ppm (range about 0.05 to 1 ppm).

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