Sulfadimethoxine and Ormetoprim (SMOR) – Medicating Ingredient Brochure

Status: Veterinary prescription required for approved claims

Date of revision: April 2018

Table of approved species and claims
Approved livestock species Approved claim(s)
(abbreviated)Table note 1
Withdrawal time Name of approved brand(s)
Salmonids (trout and salmon)
  1. Treatment of furunculosis
42 days (meat or released as stocker fish) Romet 30 Medicated Premix

Salmonids (trout and salmon)

Table of approved claims and brands
Approved claims Name of approved brand(s) Drug concentration in DIN product
Claim 1 Romet 30 Medicated Premix
  1. Sulfadimethoxine at 40 g/kg
  2. Ormetoprim at 50 g/kg

Claim 1

For the treatment of furunculosis in salmonids (trout and salmon) caused by Aeromonas salmonicida strains susceptible to the sulfadimethoxine and ormetoprim combination.

Level of medicating ingredient in a complete feed

5 g of Romet 30 Medicated Premix/100 kg of fish body weight per day.

Additional information (not to appear on feed labels)

For feed manufacturers

  • Feed labels must state one specific drug level of sulfadimethoxine and ormetoprim (see Table 1).

Directions for use in a complete feed

This livestock feed contains a medically important antibiotic. To reduce the development of antimicrobial resistance and maintain effectiveness, use this antibiotic prudently.

Feed this medicated feed as the sole ration for ten consecutive days to provide approximately 15 mg of active ingredients per kg of live body weight of fish per day.

Additional information (not to appear on feed labels)

For feed manufacturers

  • Preparation of medicated feeds:
    • Establish the weight of the fish to be treated and calculate the amount of feed needed per day according to fish size and water temperature.
    • Calculate the amount of medicated premix required for medicating the feed at the rate of 5 g of premix/100 kg of fish body weight per day.
Table 1: Preparation of medicated feed before pelletizing or extruding
Feed Intake of Fish as Percent (%) of Body Weight Kilograms (kg) of Romet 30 Medicated Premix required per tonne of feed
Thoroughly mix the calculated amount of Romet 30 Medicated Premix into the mash feed prior to pelletizing or extruding. 1
  • Medication of feed after pelletizing:
    • Prepare a liquid slurry by suspending the premix in vegetable oil or a 5% gelatin solution.
    • Coat the pelleted fish feed with the slurry, which should be constantly agitated to ensure uniform suspension of the premix during addition.
    • As a general rule, one litre of vegetable oil or gelatin solution is required to coat 25 kg of pellets. For example, to medicate 3,000 kg of fish for one day, with a 3% body weight feed intake, mix 150 g of premix with 4 litres of vegetable oil to prepare slurry to be used for coating 90 kg of pellets.
    • Pellets may be placed in a cement mixer (if 25 kg or more is to be coated) or spread on plastic or a smooth concrete surface for the coating process.
    • The pellets should be mixed constantly but gently while the slurry is being slowly added to ensure even distribution without undue pellet breakage.
    • The coated pellets are then spread out and allowed to air dry for several hours. Re-bag and store under proper feed storage conditions.
  • Store Romet 30 Medicated Premix in a dry place at room temperature (15°C - 30°C). Close bag securely after use.


  1. Treated fish must not be released as stocker fish or slaughtered for use in food for at least 42 days after the latest treatment with this drug when the water temperature is 10°C or above.
  2. Do not use when the water temperature is below 10°C.

Additional information to be added as a note to feed labels


  1. If fish show no improvement within 4 to 5 days, or if signs of disease reappear after termination of treatment, re-evaluate management practices, diagnosis of outbreak, and establish the susceptibility of the bacterial isolate(s) to the drug.

Accepted Compatibilities