Tilapia Topic, Disease Treatment,

Masoten (dipterex, dylox, neguvon, trichlorofon, trichlorfon)

Types of Masoten used to treat fish.

Masoten comes in several formulations that differ in concentration of active drug. The activity level will be given on the label, usually as a percent value.

Information about Masoten

Masoten is the trade name for an organophosphate insecticide that has been in use for many years to control certain metazoan ectoparasite diseases of fish. The chemical composition for masoten is O,O-dimethyl-2,2,2-trichloro-1-hydroxyethyl phosphonate or O,O-dimethyl-1-hydroxy-2-trichloro methyl phosphonate. There are many trade name synonyms for these compounds, the more common include masoten, dipterex, dylox, neguvon and trichlorofon.

Masoten is a toxic chemical to man and other animals. When handled, great care must be given to prevent contact or inhalation exposure to the drug. Gloves should be worn and weighing of the compound done under a fume hood, if possible.

Masoten is used primarily to treat infections by metazoan ectoparasites of fish including monogenetic trematodes, parasitic copepods (e.g. Caligus and anchor worms), Argulus (fish lice) and leech infections. While initial treatments are often very effective, the above parasites usually develop resistance to the chemical and repeated applications may have less and less benefit.

Masoten treatment is given as an overnight bath. The chemical breakdown quite rapidly in water, especially at higher temperatures or high pH. Treatment levels vary between 0.25 to 0.5 mg/l of active compound. Dosages should always be started at the lower level and if adequate effect is not achieved, then retreatment at a higher dosage tried. Masoten can be broken down rapidly in water by bringing the water to a pH of 11 or higher by the addition of sodium hydroxide.

For the crustacean parasites and Argulus, re-treatment at five to seven day intervals for a total of four treatments has often been suggested in the literature.

Equipment and supplies needed for masoten treatment.

1. Masoten
2. Gram scale
3. Gloves
4. Fume hood

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