Fish models in behavioral toxicology: Automated techniques, updates and perspectives

Introduction Since the science of toxicology began thousands of years ago, behavioral endpoints have been used to study the effects of chemicals and drugs on humans and other mammals. In aquatic toxicology however, the nexus of behavioral sciences with the study of toxicants has only become prominent within the last 5 decades. Behavioral endpoints have been slow to be integrated in aquatic toxicology because, until recently, there was a poor understanding of how alterations in behavior may be related to ecologically-relevant issues such as predation avoidance, prey capture, growth, stress resistance, reproduction and longevity. Further, the ability to achieve repeatable, quantifiable data from a large number of animals or exposures has been challenging. Recent improvements in computer and video automation have made possible significant progress in the ease, utility, and affordability of obtaining, interpreting, and applying behavioral endpoints in a variety of applications from water quality monitoring to use in toxicity identification evaluation (TIE) (Gruber et al. 1994; Balk et al. 1996; Baldwin et al. 1994a,b; Diamond et at. 1990; ATSM, 1995; Drummond et al. 1986, 1990; Rice et al. 1997). Consequently, behavioral endpoints in aquatic toxicology are shifting from being met with skepticism by investigators to being received with greater enthusiasm. One of the first comprehensive reviews on aquatic behavioral toxicology was published by Rand (1985). Over the past 20 years, the field of behavioral toxicology has grown, in part, because of increased interest in the number of species used, endpoints measured, and methods to collect and interpret data. Numerous reviews have traced these advancements in the field of Behavioral Toxicology (Døving, 1991; Weber and Spieler, 1994; Gray, 1990; Little and Finger, 1990; Little and Brewer 2001). However, the recognition of behavioral toxicology as an important tool in aquatic toxicology is most clearly seen in the acceptance of behavioral endpoints in federal regulations. In 1986, the U.S. government accepted avoidance behavior as