Barron, M. G., Stehly, G. R., and Hayton, W. L., 1990, Pharmacokinetic modeling in aquatic animals. 1. Models and concepts: Aquatic Toxicology, v. 17, no. 3, p. 187-212. Abstract: While clinical and toxicological applications of pharmacokinetics have continued to evolve both conceptually and experimentally, pharmacokinetics modeling in aquatic animals has not progressed accordingly. In this paper we present methods and concepts of pharmacokinetic modeling in aquatic animals using multicompartmental, clearance-based, non-compartmental and physiologically-based pharmacokinetic models. These models should be considered as alternatives to traditional approaches, which assume that the animal acts as a single homogeneous compartment based on apparent monoexponential elimination. Keywords: aquatic-animals, models, aquatic-organisms, animals, reviews, toxicity-testing, pharmacology, pharmacokinetics, pharmacokinetic-modelling