The University of Iowa

Xenopus (Policy)

Policy: The IACUC has provided a set of guidance documents (Policies, Guidelines, and Informational Sheets) for use when planning animal procedures at the University of Iowa. An exception to a Policy must be described and justified in the Animal Protocol and approved by the full IACUC at a convened monthly meeting.

Purpose:  The purpose of this document is to describe when Xenopus species are covered by the Public Health Service Policy (PHS) on Humane Care and Use of Laboratory Animals.  In addition this document will describe when it is required for Xenopus to be housed in OAR facilities.  This document will also describe husbandry standards for Xenopus species housed in satellite housing areas.  This document is intended for use by researchers and research staff at the University of Iowa.

Requirement for Submission of an Animal Protocol1

  • Live embryonated eggs are only applicable to the PHS Policy once they hatch. Any Xenopus sp. used beyond Nieuwkoop and Faber stage (NF) Stage 36 (when hatching begins) requires an IACUC approved Animal Protocol.
  • Adult males and females producing/laying the eggs are covered by the Policy and thus require an IACUC approved Animal Protocol


Housing Location

  • Housing of Xenopus beyond Nieuwkoop and Faber (NF) stage 36 outside of OAR vivaria must be described in an Animal Protocol and approved by the IACUC
  • Larval forms of frogs may be housed in the lab with prior IACUC approval until they are mature (i.e. hormone responsive)
  • Housing within OAR vivaria is required once frogs are mature
    • Xenopus laevis (length from nose to cloaca):
      • 5-9 cm (1.9-3.5 inches) = males mature (hormone responsive);
      • 6.5-9+ cm (2.5-3.5+ inches) = females mature (hormone responsive)
    • Xenopus tropicalis:
      • > 6 months = adult (hormone responsive)


Monitoring of Environmental Conditions (room/enclosure temperature) *

  • Housing temperature must be monitored continuously and logged at least once a day (see record keeping)
  • A remote access environmental monitoring system must be used


Record Keeping

  • Husbandry log/records are required starting at NF stage 36-45 and must be kept in the housing room
  • Animals must be fed at least daily or more often as required when appropriate for the NF stage (example: most tadpoles may start to be fed twice a day at NF stage 55)
  • The following must be documented:
  • For Xenopus NF stage 36-45
    • Daily recordings
      • Room/enclosure temperature
      • Observation of tadpole health
    • When the activity occurs
      • Water changes*
      • Feeding *
    • Records must indicate the age of Xenopus in any given container
  • For Xenopus NF stage 45 until hormonally mature  
    • Daily recordings
      • Room/enclosure temperature
      • Feeding
      • Observation of tadpole/froglet health
    • When activity occurs
      • Water changes*
    • Records must indicate the age of Xenopus in any given container


* If unfamiliar with Xenopus husbandry practices, please contact an OAR veterinarian for guidance





Last Reviewed by the IACUC 12/13/2023