Fish and Aquatic Conservation

17β-Estradiol INAD #12-671

photo of Juvenile Brook trout in a stream
Brook trout juvenile in a stream with a rocky bottom. Credit: Ryan Hagerty/USFWS


17 β -estradiol (E2) will be administered as a medicated feed and is only available to FDA approved facilities. The primary goal of studies conducted under INAD #12-671 is to generate data evaluating the efficacy of E2 administered in feed to larval brook trout to produce feminized male fish that produce eggs. The treatment option that is allowed for brook trout is a dose of 20 mg active drug/kg feed at 4% body weight per day to fry for 60 days. No retreatment will be allowed. No release of treated fish with E2 will be allowed. This INAD requires all participants to be approved by the FDA Environmental Team prior to participation – this review will take 100 days. To participate in the INAD Program for E2 visit the data collecting site..

Please read the Study Protocol prior to any treatments. It contains the protocol, SDS, 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 17- β estradiol when fed as a feed additive to larval brook to produce feminized female fish that produce eggs.

Drug Name
17- β estradiol (E2)

Drug Source
Sigma-Aldrich, Inc
3306, 3300 S 2nd Street
St. Louis, MO 63118

Target pathogen(s): Not Applicable

Method of administration: Medicated feed treatment

Treatment dosage:

  • Brook Trout: 20 mg 17 β E2/kg feed at 4% body weight per day

Treatment regimen:

  • 60 consecutive days

Investigational Withdrawal period:

  • No release of treated fish with E2

Required test parameters:

  • Investigator needs to report general fish behavior and any adverse effects relating to treatment.

Limitations or restrictions on use of drug:

  • No re-treatment of fish is allowed.
  • Investigator must follow all instructions in the Study Protocol for INAD 12-671 regarding drug acquisition and handling, fish treatment and disposition, and data reporting requirements.
  • Investigator must complete Facility Effluent Information Form for discharge of E2 before use under the INAD. Contact AADAP for more information.
  • 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