Multimodal communication modulates swimming behavior in sailfin molly (Poecilla Latipinna)

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Information received from the external environment modulates reproductive behavior in vertebrates and determines when and with whom to mate. If one of these signals is not received, then the selected behavior may not occur. It is known that chemical and visual signals play a role in reproductive behavior in fish, but whether they work together is not fully understood. We hypothesize that both visual and chemical cues are necessary in reproductive behavior of the sailfin molly, and therefore we expect the fish to respond to multimodal cues in order to complete the reproductive cycle. Our objective was to analyze attractive behavior of sailfin males and females to chemical, visual and chemical + visual cues from the opposite sex. A two‐choice maze constructed of acrylic was split into two sections with each side being 106cm (L) × 30.5cm (w). At the bottom of the maze is an open mixing area, which also doubled as the starting point for each trial. Plastic mesh was placed in each half of the maze to create turbulence and even flow throughout the maze. Water was pumped from the top of the maze using a hose and exited the maze downstream through four drain holes. Previously done dye tests confirmed that the water flow was even throughout each half of the maze and exited through the drain holes without mixing at the exit point for each trial. A small clear box with holes was placed in the maze and used for the chemical + visual signal, a black box with holes was used for the chemical only signals, and a separate clear box with no holes was used for the visual only signal. The fish of the opposite sex being tested was placed in the box located in the maze about 3/4 upstream. At the start of each trial a fish was placed in the mixing area for 10 minutes in order to acclimate. It was then given access to both sides of the maze for 10 minutes which established side preference. Cues were placed on the least preferred side of the maze in order to avoid bias and the fish behavior was observed for another 10 minutes for each cue. A Wilcox rank test was used to determine the preference for each cue. Behavioral responses showed a significant visual and a visual+chemical preference for both sexes. Visual cues had higher index of preference than visual+chemical cues, which suggest a deterrent component in sailfin odors. Chemical cues alone did not elicit swimming behavior. Although it was demonstrated in previous studies that male chemical cues induce release sex steroid release in female sailfin molly. This study shows that multimodal cues are critical for the reproductive behavior of sailfin molly and opens a new avenue of research in communication of live‐bearing species.