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Office of Animal Welfare

Environmental Enrichment for Aquatic Amphibians

I. Introduction/Purpose

The goal of environmental enrichment for amphibians is to maximize species-specific positive behavior and enhance the animals’ well-being.

The Guide for the Care and Use of Laboratory Animals states that for aquatic animals, “Acceptable primary enclosures allow for the normal physiologic and behavioral needs of the animals, including … normal movement and postural adjustments … allow for conspecific social interactions…etc. ” Additionally, the Guide states that “Environmental enrichment strategies for many aquatic species are not well established…When used, enrichment should elicit species-appropriate behaviors and be evaluated for safety and utility.” The Guide provides minimal recommendations with regards to the adequate enclosure area, style, or type for amphibians.

Compatible, social, or group housing is the primary form of environmental enrichment for amphibians. Adequate water volume and depth should be provided in order to facilitate the normal behaviors of these species. In-tank environmental enrichment devices for amphibians must be carefully selected and used because they can be detrimental to both the short-term (e.g., intestinal impaction resulting from eating small portions of enrichment devices) and long-term health (e.g., the leaching of pseudo-estrogenic compounds or other toxic substances from submerged devices). The enrichment devices also should not interfere with the experimental goals.

II. Procedures

A. All amphibians will be provided with environmental enrichment unless:

    1. The investigator provides scientific justification to the IACUC as to why enrichment is not compatible with the goals of the study and the IACUC approves the variance.
      OR
    2. In the opinion of the Attending Veterinarian or designee, environmental enrichment will adversely affect the health or well-being of the animals.

A Husbandry Special Services Request form must be completed and turned in by the responsible party (Investigator group or Vet Services) to the facility supervisor if environmental enrichment is to be restricted or absent.

B. Primary Enclosures: A volume of 1 gal or 3.8L of water per individual for totally aquatic amphibians, like Xenopus laevis, with a minimum depth of 4 inches (10 cm).

C. Social Housing: Amphibians should be housed in compatible pairs or groups by size, unless an appropriate partner is not available in the same room.

D. Enrichment devices

  1. Singly housed amphibians and those in static tanks (except as provided below) should be provided with an appropriate in-tank environmental enrichment item (floating refuges or tank-bottom hiding places or shelters) that is/are constructed of materials considered safe for the health of the amphibians (e.g., human food grade polycarbonate, acrylonitrile-butadiene-styrene (ABS) or polyvinyl chloride (PVC)). Items must be constructed such that any edges or surfaces are rounded and smooth. Items must NOT be constructed in a fashion that allows small parts or portions of the item to separate from the main body and potentially be ingested by the amphibian.
  2. Examples of acceptable in-tank polycarbonate enrichment devices are Bio-Serv® – Guinea Pig HutTM or Rat HutTM.
  3. Acceptable in-tank portions of pipes must be sinkable, heavy enough that amphibians cannot move the devices around, must not interfere with tank drainage systems or water flow patterns that facilitate mechanical drainage, and be made of “food grade potable materials” like acrylonitrile-butadiene-styrene (ABS) or food-grade polyvinyl chloride (PVC).
  4. Frogs housed in flow-through tanks generally cannot have in-tank enrichment items because they interfere with the drainage system and thus result in poor water quality. Similarly, frogs housed in static tanks pre- and post-operatively cannot have in-tank enrichment items. Instead, in these situations, housing enclosures will have visual barriers located outside the tank to provide “sheltered areas” inside the housing enclosure. Such visual barriers need to be large enough so that all frogs in the tank can be present in the “sheltered area” at one time. This is necessary to prevent trauma to frogs within the enclosure.
  5. Frog Foraging: Xenopus tropicalis frogs housed in recirculating configuration will be fed live prey items three times weekly. The use of in-tank enrichment items for this species of amphibian in this type of housing configuration is not appropriate nor safe.

III. References

  1. National Research Council. 2011. Guide for the care and use of laboratory animals. Washington (DC): National Academy Press.
  2. Green SL (2011). The Laboratory Xenopus sp. Boca Raton (USA): CRC Press.
  3. Reed, BT. 2005. Guidance on the housing and care of the African clawed frog, Xenopus laevis. Research Animals Department, Science Group, RSPCA. West Sussex, UK. Guidance on the housing and care of the African clawed frog (PDF)

IV. Approval/Review Dates

SOP Created: 09/18/2007
Last Reviewed by the IACUC: 04/21/2022

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