The zebrafish has been shown to be a powerful experimental test subject for research in different areas, predominantly in neuroscience and behavior. Many classical tests used for rodents have already been adapted into or inspired new tests for fish. Nonetheless, the elevated plus maze, one of the most used experimental tests for rodents, still didn't have an equivalent for fish. In this study, we suggest a plus maze with ramp tank-in which the arms with ramps are equivalent to the opened arms of the elevated plus maze, and the flat arms are equivalent to the closed arms of the test for rodents. Since this was a pilot study, we tested different water column heights and different test lengths and the effects of alcohol and clonazepam. Our results revealed that, regardless of the height of the water column and the length of the trial, the animals preferred the flat arms in comparison to the arms with ramps, either for spending more time in or entering into those arms more times. Both drugs tested showed anxiolytic effect. Based on our results and prior studies showing anxiety-related dive responses in zebrafish, we propose that the plus maze with ramps is a valid tool for the study of anxiety, allowing the comparison of its data with data obtained from tests with rodents.

One of the tools to study anxiety is behavioral animal models. Traditional models developed in rodents can be adapted to fishes. The Plus Maze with Ramp (PMR) is a fishlike-anxiety model based on the Elevated Plus Maze, a canonical model of the rodentlike-anxiety model. Literature suggests that the Elevated Plus Maze presents sex and behavior differences of rodents between the first and the other expositions to the apparatus, an effect known as "one-trial tolerance." The present study objective was to verify the effects of guppies sex and re-exposure over the exploration parameters of PMR. To do this, both sex adult groups performed five sessions (5 min) in the PMR with different intervals inter-sessions (30 min, 60 min, 120 min, 24 hr). Our data show that the PMR environment produces an avoiding behavior from the arms with ramp; the reexposure to the apparatus cause habituation to the environment, with possible tolerance, but not one-trial tolerance, with sex-dependent related effects. The data indicate the possibility and validity of PMR use as a like-anxiety model in this species. Public Significant StatementGuppies exhibit similar anxiety behavior to zebrafishes when exposed to PMR. Reexposure to PMR causes habituation in guppies, like in many vertebrates. There is sexual dimorphism in guppies behavior exposed to PMR with sensibilization only in males.