Fish and Aquatic Conservation

Diquat® INAD #10-969

photo of a Walleye fish swimming
Photo of a Walleye. Credit: Eric Engbretson, /USFWS


Reward® (DQT) is a liquid concentrate containing diquat dibromide that is applied as an immersion bath treatment. DQT is available for purchase through many local farm & ranch stores or through Syngenta Crop Protection, LLC. The primary goal of field studies conducted under INAD #10-969 is to evaluate the efficacy of DQT for controlling mortality in all freshwater-reared finfish diagnosed with BGD or external flavobacteriosis. The treatment regimens allowed for DQT immersion are 1) 15 – 18 mg/L for 1 – 3 hours for 1 – 3 days; or 2) 28 mg/L for 1 hour for 1 – 3 days. The Investigational withdrawal period for DQT for adult Ictaluridae and Esocidae is 5 days; all other freshwater-reared finfish have a 30 day Investigational withdrawal period; if 17MT medicated feed is used with tilapia then the longer withdrawal period needs to be followed. The investigational withdrawal periods can be incorporated into the grow-out period. No prophylactic or preventive use of Diquat is allowed under this INAD. To participate in the INAD Program for DQT 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/or pivotal data needed to establish the effectiveness of diquat to control mortality caused by certain bacterial diseases.

Drug Name
Diquat (Reward®)

Drug Source
Syngenta Crop Protection, LLC (often available from your local farm & ranch store, veterinary supply outlet, etc.)
P.O. Box 18300
Greensboro, NC 27419-8300

c/o Steve Cosky, Product Biology Lead, Syngenta
Phone: 1-336-632-6000

Target pathogen(s): External flavobacteriosis (e.g. bacteria responsible for bacterial gill disease, external columnaris, and external coldwater disease)

Method of administration: Immersion: flow-through or standing bath treatment

Treatment dosage:

  • Option A: 15-18 milligram (mg) diquat per liter
  • Option B: 28 milligram (mg) diquat per liter
  • Option C: Repetitive Treatment dose as approved by FDA/CVM

Treatment regimen:

  • Option A: 1-3 hour treatment; 1-3 treatments on alternate or consecutive days
  • Option B: 1 hour treatment; 1-3 treatments on consecutive days
  • Option C: As approved by FDA/CVM

Investigational Withdrawal period:

  • 5 days for adult Ictaluridae and Esocidae.
  • 30 days for all other fish species.
  • No holding time is assigned for fish that have a grow-out period that exceeds 30 days. The investigational withdrawal periods may be incorporated into the grow-out period.
  • If 17MT medicated feed is used during the DQT treatment for tilapia than the longest withdrawal time must be followed.

Concomitant Treatments:

  • Only 17MT medicated feed is authorized to be used if needed during the DQT treatment period. No other chemicals are allowed to be administered for 2 weeks prior; during; or 2 weeks after the DQT treatment. Contact AADAP if you are treating T&E species for additional information regarding concomitant treatments.

Required test parameters:

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

Limitations or restrictions on use of drug:

  • Prophylactic (preventive) treatment of fish is not allowed.
  • Repetitive Treatment use must be approved by the FDA/CVM Environmental Team before this use pattern can be administered.
  • Only the Reward® brand of diquat can be used for INAD treatments.
  • Investigator must follow all instructions in the Study Protocol for INAD 10-969 regarding drug acquisition and handling, fish 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