Parasite-S (Canada)

Formalin (aqueous Formaldehyde Solution)

For Control Of External Protozoa And Monogenetic Trematodes On Salmonid Fish And For Control Of Fungi On The Eggs Of Salmonid Fish.

Formalin has been used since 1909 in the United States in the production of sport, commercial, and experimental fishes (Schnick 1973). It is used as a therapeutant and prophylactic for the control of external parasites on salmon, trout, catfish, largemouth bass, and bluegill, and for the control of fungi on salmon, trout, and esocid eggs. PARASITE-S has been used since the early 1970's to control external protozoans on penaeid shrimp (Johnson et al. 1973).

Parasite-S Caution

Store PARASITE-S indoors away from direct sunlight, heat, sparks, and open flames, and ventilate storage area. Do not subject PARASITE-S to temperatures below 40°F (4.4°C). PARASITE-S subjected to temperatures below 40°F causes the formation of paraformaldehyde, a substance which is toxic to fish. Paraformaldehyde can be recognized as a white precipitate at the bottom or on the walls of the container.

Tolerance to PARASITE-S may vary with strain and species of fish. While the indicated concentrations are considered safe for the indicated fishes, a small number of each lot to be treated should be used to check for any unusual sensitivity to PARASITE-S before proceeding.

Under some conditions, fish may be stressed by normal treatment concentrations. Heavily parasitized or diseased fish often have a greatly reduced tolerance to PARASITE-S. Such animals do not tolerate the normal tank treatment regimen the first time they are treated. Therefore, the time and dosage may need to be reduced. If they show evidence of distress (by piping at the surface), the solution should be removed and replaced with fresh, well aerated water. Careful observations should always be made throughout the treatment period whenever tank or raceway treatments are made. Treatment in tanks should never exceed one hour for fish even if the fish show no sign of distress.

Do not apply PARASITE-S to ponds with water warmer than 27°C (80°F), when a heavy bloom of phytoplankton is present, or when the concentration of dissolved oxygen is less than 5 mg/L (5 ppm). PARASITE-S may kill phytoplankton and can cause depletion of dissolved oxygen. If an oxygen depletion occurs, add fresh, well-aerated water to dilute the solution and to provide oxygen.

Do not discharge the contents of fish treatment tanks into natural streams or ponds without thorough dilution (greater than or equal to 10X). Do not discharge the contents of egg treatment tanks without a 75X dilution. This will avoid damage to PARASITE-S sensitive phytoplankton, zooplankton, and fish or invertebrate populations and avoid depletion of dissolved oxygen.

Do not use PARASITE-S in a tank or pond in which methylene blue, or other dyes, which are absorbed, have been recently used.

Chemistry

PARASITE-S is the aqueous solution of formaldehyde gas. 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(CH₂O)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, colourless liquid (Heyden Newport Chemical Corporation, 1961).

Fish Toxicity Studies

The toxicity of PARASITE-S was measured by standard methods in laboratory bio-assays with rainbow trout, Atlantic salmon, and lake trout. The 3, 6, 24 and 96-hour LC₅₀ (lethal concentration for 50% of the animals) values for trout range from 1,230 to 100 uL/L (455 to 37 ppm formaldehyde).

Directions For Use On Salmonoid Fish

PARASITE-S is effective for the control of external parasites on Salmonid Fish. Organisms controlled include the protozoa: Ichthyophthirius spp. (“Ich”), Chilodonella spp., Costia spp., Scyphidia spp., Epistylis spp., and Trichodina spp., and for the monogenetic trematodes: Cleidodiscus spp., Gyrodactylus spp., and Dactylogyrus spp.

Directions For Use On Fish

CONCENTRATION - Concentrations used for treatment are expressed as microlitre (uL) of formalin (37% formaldehyde) per litre of water and are equivalent to parts per million (ppm).

Table 1. Concentrations required for control of parasites on fish.

Use the lower concentrations when the pond is heavily loaded with fish, shrimp or phytoplankton.

uL/L = microlitres per liter (ppm)

The figure in parentheses denotes the concentration of formaldehyde expressed as parts per million (ppm) by weight.

A single treatment usually controls most parasites but it may be repeated in 5-10 days, if needed.

Table 2. Amounts of PARASITE-S needed to supply effective concentrations in selected volumes of water.

Methods Of Application

Application To Tanks And Raceways - Turn Off Water Supply, Provide Aeration, Apply The Appropriate Amount Of Parasite-s And Thoroughly Dilute And Mix To Assure Equal Distribution Of Parasite-s. Treat For Up To One (1) Hour For Fish, Then Drain The Solution And Refill The Tank With Fresh, Well-aerated Water. While The 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 Once A Day Until Parasite Control Is Achieved.

application To Ponds - Apply Greatly Diluted Parasite-s To The Pond Evenly Using A Pump, Sprayer, Boat Bailer, Or Another Suitable Device To Assure Even Distribution. Allow Parasite-s To Dissipate Naturally. Single Treatments Usually Control Most Parasites But They May Be Repeated In 5-10 Days If Needed. Treatments For ichthyophthirius Should Be Made At 2-day Intervals Until Control Is Achieved.