The olfactory system contributes to a fish's success in sustaining life—to feeding, avoiding predation, spawning migration and reproductive activity, even parental care, and offspring–parent interactions. This chapter presents a world of scent from the perspective of the cells and neural pathways that respond to odors and channel olfactory input to behavioral responses. The chapter provides a comparative review that highlights the variation in the morphology and function of the olfactory system of fishes. It presents a phylogenetic assessment of the gross anatomy of the peripheral olfactory organ, a synopsis of olfactory receptors (ORs), of transduction events, and the channeling of responses to brain centers. The nasal cavity of fish enables the interaction of odorants to odor receptors and olfactory activity. There is diversity in the anatomy of the nasal cavity and the development of one or two accessory nasal sacs that assist in guiding the flow of odorants over the olfactory epithelium, particularly in the Acanthopterygii. The chapter suggests that researchers consider the odorants and behavioral responses of fish in their natural environment. The olfactory bulb is important for odorant recognition and projects olfactory sensory input into appropriate brain regions. However, the mechanism for channeling through the olfactory bulb is not entirely understood, and the specific role of interneurons in olfactory memory and odor recognition is also unknown.
Zielinski, Barbara S. and Hara, Toshiaki J., "Olfaction" (2006).