Aristotle's Fish: the case of the kobios and phucis

Aristotle was a remarkable observer of the living world. He made detailed observations on the anatomy and life history characteristics of many organisms as part of a larger study into the differentiae (diaphora) of groups of animals. This reexamination of Aristotle's observations of two small fishes is a study into the work or the way of being of particular organic wholes. As such, it is directed by three main objectives: to evaluate the accuracy of those observations Aristotle makes with regard to the kobios and phucis in the History of Animals, as well as to understand how he might have conducted his research; to determine whether aspects of those observations would ground more philosophical arguments; and to contribute to the understanding of the basic biology of these fishes. In so doing, this article also may introduce a new generation of biologists to the richness of Aristotle's biological observations and the questions that motivated them.