Guidelines developed for the research laboratory may be similar to those developed for a centralized facility. All
incoming animals should be quarantined and acclimated before use in experiments. For toxicology and carcinogenicity
research, the exposure route must be well evaluated. For aqueous exposures, tests may be conducted in static, staticrenewal,
or flow-through systems. The choice of system depends on the toxicant, the test species, the compound being tested, and available resources (EPA 1989,1991). In general, flow-through systems are preferable because they cause fewer fluctuations in water quality. Commercial flowthrough toxicant delivery systems, however, are expensive and complex. Static systems have been widely used in research, especially with early life stages of small species such as the fathead minnow.