Crustaceans utilize water‐borne‘chemical signals’to identify and orient toward potential prey. These chemical signals are recognized in spite of the chemical complexity of aquatic environments. Because feeds are a significant expense in all aquaculture operations, the need to maximize feeding rates and reduce wasted feed, thereby lowering production costs, is paramount to economic success. Confusion concerning the function and utility of chemoattractants versus feeding stimulants in aquatic feeds necessitates updated terminology. Simply put, detection does not equal attraction. To accurately describe and predict responses to feeding stimuli, it is necessary first to classify all possible stimulus types and then to categorize behavioural responses to each specific stimulus. The proposed hierarchical behavioural model classifies an animal's response to chemical stimuli into five phases: (1) detection; (2) orientation; (3) locomotion or displacement; (4) initiation of feeding; (5) continuation or termination of feeding. The second step in description of the behavioural model is the association of specific behaviours with these five phases of response. Crustaceans exhibit four major categories of chemotactic behaviour: antennule flicking, which appears to be the most sensitive; probing movements made by the pereiopods that precede locomotion; locomotion by the crustacean, indicating true attraction or repulsion; and movements by the mouthparts that indicate generalized feeding stimulation. Finally, feed and environmental quality have direct effects on the effectiveness of feed attractants/stimulants; food detection and feeding stimulation ultimately determine the commercial value of an aquatic feed.

In a recently developed paradigm for the feeding behaviour of Crustacea, chemical stimuli are postulated to play a key role in mediating the various stages of feeding from initial excitation to sustained feeding. A hierarchical testing protocol for the screening of compounds or mixtures as chemical stimuli for Penaeus spp. was designed, utilizing: (a) a static chamber for an initial rapid assay for behavioural excitation; (b) a novel flow‐through chamber for demonstrating chemotaxis; (c) a modified Y‐maze choice chamber for more detailed studies on chemotaxis and feeding stimulation; and (d) aquarium feeding trials in which the most potent chemical attractants and/or feeding stimulants are incorporated into experimental feeds. In shrimp aquaculture, efficient feed utilization is of paramount importance to the economics of production and water quality. Identification and incorporation into the feed of ingredients that act as chemoattrac‐tants and/or chemical feeding stimulants should lead to better food utilization, e.g. lower feed conversion ratios (FCRs), thereby producing quicker growth rates and lowering the incidence of water pollution and disease.

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