Fish and Aquatic Conservation

Florfenicol (Aquaflor®) for Lobsters INAD #12-061

This American Lobster (Homarus americanus) was photographed in 15 feet of water in Plum Cove, Gloucester, Massachusetts during an eelgrass monitoring survey.
Credit: Environmental Protection Agency


Aquaflor® is an aquaculture premix containing florfenicol and is only available through Merck Animal Health. Aquaflor® medicated feed can be purchased through aquaculture feed mills. The primary goal of field studies conducted under INAD #10-697 is to evaluate the efficacy of florfenicol-medicated feed for controlling mortality in lobsters (Nephropidae and Palinuridae) with a variety of diseases that are caused by pathogens susceptible to florfenicol. The primary pathogen of interest is Photobacterium indicum. Two treatment options are allowed; administer Aquaflor® in feed at either 10 or 15 mg active florfenicol per kg lobster per day for 10 consecutive days. The Investigational withdrawal period is dependent upon dosage administered; 21 days for 10 mg/kg and 28 days for 15 mg/kg. To participate in the INAD Program for Aquaflor® visit the data collecting site.

Please read the Study Protocol prior to any treatments. It contains the protocol, MSDS, and a copy of the forms to be used as a guide for collecting data that will be entered into the online INAD database. The FDA authorization letter(s) for this INAD is currently only available by emailing Bonnie Johnson .

INAD objective/purpose: Collect supportive and pivotal data needed to establish the effectiveness of florfenicol to control mortality caused by certain bacterial diseases in lobsters.

Drug Name
Florfenicol (Aquaflor®)

Drug Source
Merck Animal Health
35500 W. 91st Street
De Soto, KS 66018

Kasha M. Cox
Phone: 662-907-0692

Target pathogen(s): Bacterial pathogens susceptible to florfenicol, although the primary bacterial pathogen of interest is Photobacterium indicum.

Method of administration: Medicated feed treatment

Treatment dosage:

  • 10 or 15 milligrams (mg) florfenicol per kilogram (kg) lobster body weight per day

Treatment regimen:

  • 10 consecutive days

Investigational Withdrawal period:

  • 21 days for treatment at 10 mg/kg body weight
  • 28 days for treatment at 15 mg/kg body weight
  • No Investigational withdrawal period is required for lobsters that are not susceptible to legal harvest for a period post-treatment equal to the Investigational withdrawal periods noted above or are illegal for harvest during those same periods.

Required test parameters:

  • Investigator must collect mortality data throughout the 5 day pre-treatment, treatment, and 10-day post-treatment period. Investigator should also report general fish behavior and any adverse effects relating to treatment.

Limitations or restrictions on use of drug:

  • Investigator must follow all instructions in the Study Protocol for INAD 12-061 regarding drug acquisition and handling, lobster treatment and disposition, and data reporting requirements.
  • Drug discharge must be in compliance with local NPDES permitting requirements.

Required INAD fee: $700/facility/year

AADAP Contact Information:
Ms. Bonnie Johnson, FWS-AADAP
Phone: 406-994-9905
Fax: 406-582-0242