Share thisAs successively larger populations and more generations of zebrafish are maintained in the laboratory environment, it is becoming more incumbent on the community of people raising them, and those defining the standards for their care, to better define these ideal conditions. This effort is only beginning.
The use of the zebrafish as a laboratory animal model has exploded over the last decade. Indeed, the care and use of various aquatic animals (including medaka, Xenopus spp, fathead minnows, axolotls, urchins, and many more) in the laboratory setting has grown dramatically. This article will focus on the zebrafish, although the premise applies equally to these other prominent aquatic animal models. The primary reasons most often cited to explain the growth in the use of zebrafish are a comparison of the animal relative to mammalian models in its fitness for the purpose (the primary purpose being the description of human development and disease). One of the lesser cited advantages of this animal model, however, is its ability to be maintained and bred in a relatively wide range of environmental conditions. This hardy nature has allowed the science to move forward in advance of a concurrent effort to truly understand the ideal environmental requirements of the animal and its application in the laboratory setting.
The zebrafish was introduced as an animal model by George Streisinger in the 1970s when he sought an alternative model for the study of genetics and development in vertebrates. His decision was motivated, in part, based on the relative ease with which the animal could be maintained and bred. It is ironic that these attributes have allowed the research community to exponentially increase the use of the zebrafish as an animal model without a corollary increase in directed research of specific husbandry requirements. As the use of the zebrafish has increased throughout the world, individual institutions and labs have devised and evolved a variety of unique protocols for its care and use. Protocols for feeding, density, water quality, and breeding, among others, are often very different from laboratory to laboratory. Until recently, there was no apparent drive for consensus on the correct husbandry conditions and protocols for the animal. Complicating matters is the fact that there are a number of different stakehold-ers, from veterinarians, principal investigators, laboratory animal technicians, and others, with unique requirements and insights into the issue.
All of this being said, it is important to note that generalized care standards do exist. As vertebrates, the zebrafish fall under the revised Guide for Care and Use of Laboratory Animals.1This is the main body of work used by investigative authorities such as the Association for Assessment and Accreditation of Laboratory Animal Care International (AAALAC International). An Institutional Animal Care and Use Committee (IACUC) will also follow such guidelines as a baseline. To date, however, a committee’s ability to properly assess care is left to interpretation of information presented by a particular research group. Outside of personnel safety and obvious detriments to the animal, a research group must simply provide and document criteria for housing and care. As mentioned above, these criteria vary greatly throughout the research community. A call to develop more rigorous standards appears to be rising in multiple places and from each of these stakeholder groups.