Shoaling in zebrafish: what we don't know

Zebrafish have been gaining increasing popularity in behavioral neuroscience. However, the number of behavioral test paradigms specifically designed for zebrafish, and in general the amount of information available on the behavior of this species, is relatively small when compared with classical laboratory model organisms such as the mouse, the rat, and the fruit fly. A particularly typical behavioral feature of zebrafish is shoaling, i.e., group formation. Given the importance of social behavior in our own species and the fact that zebrafish possess several characteristics similar to those of other vertebrates, including humans, at many levels of biological organization (e.g., neuroanatomy, neurochemistry, biochemical processes, and amino acid sequence of proteins or nucleotide sequence of genes), the zebrafish is expected to be an excellent tool not only for basic research but perhaps also for translational research. Briefly, we propose that once social behavior of the zebrafish is better characterized and once appropriate behavioral methods have been developed, this species can be utilized for the analysis of the mechanisms of social behavior of other vertebrates including our own. In this review, we discuss general principles of shoaling and highlight what we know and what we do not know about this behavior as it pertains to zebrafish.