Few of the approximately 70,000 chemicals on the Toxic Substances Control Act inventory or the 1000 to 1600 new chemicals introduced each year in the United States have been tested for neurotoxicity to support risk assessments (NRC, 1992), even though it is estimated that 5 to 10% of them are likely to be neurotoxic. Neurotoxicity has been defined as adverse effects of physical, biological, or chemical agents on the structure or function of the nervous system in developing or adult organisms (Philbert et al., 2000). From a human health risk assessment perspective, the potential for neurotoxic effects associated with synthetic chemicals has led to the development of valid, sensitive, and reproducible methods to identify neurotoxic chemicals, to characterize neurological effects, and to determine the mechanisms by which chemicals produce neurotoxicity. Similar efforts to develop methods for assessing neurotoxicity in fish may yield further insights into neurotoxic mechanisms.