Quantitative chemobehavior of fish: an improved methodology

Synopsis A new behavioral monitoring system, an octagonal fluviarium, and associated time-series analytical techniques were developed to quantitatively examine and assess the chemobehavior of fish to waterborne chemicals. Together they aid in the solution of many of the quantitative behavioral and physical problems inherent in earlier experimental approaches. The fluviarium utilizes a quasi-circular channel in which fish are able to move freely through any of eight areas, any of which can receive a predetermined concentration of a chemical stimulus. Movements and preferential stays of animals monitored with a video system are analyzed to determine spatial and temporal preference in their distributions within the system in response to introduced chemicals. The advantages of these designs include precise control of the water flow dynamics affecting the odor plume, virtual elimination of the wall-hugging tendency of animals due to the quasicircular construction of the octagonal trough, and the assessment of temporal changes in the behavioral responses of the animals which can be correlated with the presence of odoriferous cues. The efficacy of the fluviarium and statistical analysis is illustrated with data on the chemoresponse of zebrafish, Brachydanio rerio, to 1 × 10^–3 M L-alanine. Our system should have extensive application in investigating the chemoresponses of aquatic organisms to waterborne chemicals (presented singularly and in combinations) such as food substances, pheromones or pollutants.